timber form & construction 1

7/22/2019 Timber Form & Construction 1

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Evaluate and appraise a selection of joints from both theeastern and western traditions.

And assess their buildability and performance comparatively

AuthorStudent 100197432011


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Traditional joints

Eastern joints

1 . Kamatsugi

1.2 Koshikake kamatsugi

1.3 Mechigai hozotsuki kamatsugi

2 . Sen2.1 Komisen

2.2 Hanasen

2.3 SHachisen

2.4 Yokosen

2.5 Hiyodorisen

3.Kanawatsugi

3.1 Okkake daisentsugi

3.2 Shachi

3.3 Shippasamitsugi

Western joints

1.Tongue-And-Groove

How to Make Tongue and Groove Joints

1.1 Tongued and Grooved Flooring Board

1.2 Tongued and Grooved Matchboarding

1.2.1 Tongued, Grooved and Beaded

1.2.2 tongued, grooved and veed

1.2.3 Double tongued and grooved

1.2.4 Dovetail Tongue and Groove

1.3 Tongued and Grooved Mitre

2. Birdsmouth joint

How to Cut a Birdsmouth Joint

3. Half joint

How to Make half lap Joints

Different between Eastern and Western joint

Shape and structure

Different in Protection and prestige

Different in Protection sill beam

Different in Construction

Different in Log construction

The function of wood joint

The role of the toolsThe influence of climatic condition

Different in nominate.


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Royal Botanic Garden - John Hope Gateway

Introduction

Building Description

Concept Design

Landscape Description

Inside Description

Structure

Materials

Roof Structure

Stair

Cladding and GlazingFire Resistance and Timber Surface Treatment

Sustainability

Conclusions

Reference, Traditional joints

Reference, Royal Botanic Garden - John Hope Gateway


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1 . Kamatsugi

1.1 A gooseneck tenon and mortisejoint. The mortise is cut into one

section, and the tenon, with head and

neck a single member, is cut into theother. The neck of the tenon is

roughly square or rectagular and

varies in length according to need.

Kamatsugi were used as early as the

7c. By the medieval period (13c-16c),

the head was tapered and resembled

a blunted arrow. A variation

resembling a double gooseneck with

heads at each end of the tenon is set

into the mortise of the same shape.

Usually used to connect two beams.

The joint is called chigiritsugi (Figure 1.1)

1.2 Koshikake kamatsugi

also called shikimen kamatsugi. A half-lap, gooseneck tenon joint. An end joint

which combines two joints: a half-lap koshikaketsugi and a gooseneck tenon

joint kamatsugi. The gooseneck mortise and the bench, or seat, of the lap joint

are cut so that the mortise occupies about half the thickness of the timber.

The bench made from the remaining half extends like a step beyond the

mortise. The second timber contains the gooseneck tenon; the undercut

overlaps the bench when the tenon is dropped into place in the corresponding

mortise. If a half-blind mortise, (mechigai hozoana), is cut vertically into the

center of the bench and a matching tenon is made on the undercut part

beneath the dovetail, the combination joint is called koshiire mechigaitsuki

kamatsugi. The half blind tenon prevents damage from twisting forces.(Figure 1.2)

Figure 1.1 : Chigirtsugi

Note :Spline joints using small pieces of

wood, tenons inserted into the slots,

mortises, cut in corresponding shapes on

the timbers to be joined. The spline derives

its basic shape from combining the narrow

ends of two dovetails. There are various

types, for example, the bow-tie spline

kinekata and the dumbbell spline areigata.

If the splines join timbers parallel to the

grain, the spline is usually lengthenedImage: Kiyos,Seiko


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Koshikake kamatsugiis based

on the same principles as

koshikake aritsugi(Figure 1.2.1 );

only the shape of the tenon and

mortise differ. koshikake

Frequently used to join twohidden purlins (roof joints),

nogeta, and foundation

footings, dodai.

Figure 1.2.1 : koshikake aritsugi

Image: Kiyos,Seiko

Note: A half-lap, dovetailed joint. An endjoint which combines two joints: a half-lap

and a dovetail. The dovetail mortise andthe bench, or seat, of the lap joint are cutso that the mortise occupies about half thethickness of the timber. The bench madefrom the remaining half extends like a stepbeyond the mortise. The second timbercontains the dovetail tenon; the undercutoverlaps the bench when the dovetailtenon is dropped into place in thecorresponding mortise. If a half-blindmortise, mechigai hozoana, is cut vertically

into the center of the bench and amatching tenon is made on the undercutpart beneath the dovetail, it is calledkoshiire mechigaitsuki aritsugi(Figure 1.2.1.1).The half blind tenon prevents damage fromtwisting forces.

Figure 1.2.1.1 : koshiire mechigaitsuki

aritsugi, Image: Kiyos,Seiko

Note: A half-lapped, half-blind, tenoned

dovetail joint. The indented piece is cut

with a bench, lit. hip koshi, open in the

centre to receive the half blind tenon

mechigai. The dovetail and half blind

tenons fit into a dovetail-shaped cavity.

Besides having a half blind tenon, the

tenoned piece also has extended shoulderswhich rest on the benches on each side of

the opening for the blind tenon and the

dovetail. The same principle applies to the

half-lapped, half-blind, tenoned gooseneck

joint mechigaihozotsuki kamatsugi

ogi kubi kama shikimen megi

Figure 1.2 Koshikake kamatsugi,

Image: Kiyos,Seiko


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Figure 1.3 mechigai hozotsuki kamatsugi

Image: Kiyos,Seiko

1.3 Mechigai hozotsuki kamatsugi`corners made by the projection of the neck from the beam.

A blind mortise is cut on the lower half of the matching piece.

The upper sides are adjacent to the gooseneck mortise and are cut away

to form benches koshikake, on either side of the blind mortise.

These fit snugly into the cutaway sides of the blind tenon.

A variation used to further strengthen the joint and prevent twisting

includes right angled blind mortises which may be cut on either side of

the entrance for the neck. Blind tenons are then cut into the matching

piece.

The shape of the joint is visible on top, but from the side, it appears

to be an ordinary splicing joint. This joint is used for purlins andground sills and must have supporting members beneath it.


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2 . Sen

Also called komisen. A pin, peg, key, cotter or dowel made of hardwood,

usually oak. It varies in shape and size depending upon need and placement.

It is added to butt or end joints tsugite, and to angle joints shiguchi, for

strength and security. Holes are bored where necessary and pins are insertedand may pass through tenonned and indented pieces. The sen may be blind

and only partially inserted to prevent slippage. There are many kinds of sen:

2.1 Komisen or daisen. A blindjoint with pins slightly off center.

Komisengama is gooseneck joint

with pins or a mortise-and-tenonjoint used on a penetrating tie beam

nuki. It is characterized by the

addition of a pin or key inserted

through the head of the tenon hozo

into the top of the pillar for purpose

of tightening and strengthening the

joint.(Figure 2.1 Komisen)

Figure 2.1 Komisen

Image : Yasuo,nakahara & paul nii

2.2 Hanasen (lit. nose pin).

A blocking draw pin used in

vernacular houses minka . For

example, a suspended strut

tsurizuka, is joined to a purlin keta.

The end of the transverse beam

hari, in the roof framework is cut

into a large tenon that extends

through and beyond the outer

surface of the pillar. In order to draw

the nose of the beam tightly to the

pillar and to prevent the pin from

penetrating the post or fromslipping, the pin hanasen is cut at

an angle and is driven through a

mortise cut in the extended tenon.

(Figure 2.2 Hanasen)

Figure 2.2 Hanasen



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Figure 2.4 yokosen


2.3 SHachisen or shachi

are slightly tapered keys placed in

hunched or right angle mortises

formed by oblique positioning of

matching right angle cuts in both the

tenon and beam. When these parts arejoined, the key's tapered ends are

pounded into the resulting slots. The

slots may be aligned, half or fully

staggered. If two boards are held

together by shachisen, only mortises

are made obliquely, part on each

board, to receive the pin. See (Figure 3.2.1saoshachitsugi), (Figure 3.2.2 saobiki dokko)

2.4 Yokosen

a threshold-to-post pin. This is

driven horizontally into a groove

where the threshold and post meet.(Figure 4.3 yokosen)

2.5 Hiyodorisen

A long cotter with a head,(kashirasen), that passes through

the tail rafters, (odaruki), wherethey meet at right angle on eachside of the hip tail raftersumiodaruki. It protrudes beyondthe rafter on the side opposite itsentry. A small pin called a magosen(lit. grandchild pin) is driven throughthe protruding part to preventslippage and to tighten the pin. It isused in shrine and templearchitecture.(Figure 5.3 hiyodorisen)

Figure 2.5 hiyodorisenImage : Yasuo,nakahara & paul nii

Top (Figure 2.3 SHachisen

Right (Figure 2.3.1 saoshachitsugi),

Bottom (Figure 2.3.2 saobiki dokko).



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3 Kanawatsugi

An oblique, housed (dadoed), rabbeted,T-shaped, half-blind, tenoned scarfjoint. Because both the tenon andmortise are blind, the joint cannot beslipped together from the side, as in anoblique, housed, rabbeted, scarf jointokkake daisentsugi (Figure 3.1 ). Theoblique surface on the mortised half ofthe indented part is decreased by thedepth of the rabbet. Therefore, the endwith the inverted T-tenon on the

corresponding piece must be insertedin a lengthwise direction. Then a joiningdraw pin komisen is driven through theopening provided in the center to lockthe joints.

Sometimes two keys shachi(Figure 3.2)are used in place of a draw pin tostrengthen the joint.

Figure 3.1 Okkake daisentsugi

Note : An oblique, housed (dadoed) and

rabbeted scarf joint. The upper and

lower pieces are exactly the same but

reversed. The upper part is fitted into

the lower part from the side and two

pins komisen are driven through the two

mortises. The result is a very tight and

stable joint used to join ground sills and

various beams that must withstand

great stress and strain. Okkake tsugiis

identical to okkake daisentsugiexcept

that pins are not inserted. Image: S.Azby

brown

Figure 3.2 Shachi

Note: An abbreviation ofshachisen. A draw pin, key or

cotter made of hard wood, usually zelkova or oak. The

pin is long and thin, with a square or circular cross-

section. It is driven into the upper and lower parts of a

joint, either diagonally or at right angles, to prevent

slippage. Often used to secure joints such as the

saotsugi. Image: S.Azby brown

Figure 3 Kanawatsugi

Image: S.Azby brown


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This joint is commonly used in foundation footings dodai (1) , wall plates

daiwa (2), the beam used for the bottom tracks for sliding doors or window

shikigeta(3) , and in eave purlins dashigeta. The improvement in carpenter's

tools in the Edo period made it possible to fashion complex joints such as this.

Note :

1. Dadoi

A sill, ground sill or footplate. Generally the heavy timber members laid horizontally

at the base of a wooden building upon which pillars or posts are erected. Occasionally, it

is called a sill frame because it forms a grid pattern when laid on all four sides. If ground

sills are provided under wall partitions, they are called partition sills majikiri dodai. In

some small shrine buildings the footplates are laid directly on the ground.2.Daiwa

A wall plate or top plate placed along the top of head-penetrating tie beams or A

circular plate placed on the top of a pillar.

3.Shikiaeta

A beam placed on top of a wall

3.3 Shippasamitsugi

A type of kanawatsugi, a mortised, rabbeted, oblique, spliced joint.

Also called shiribasamitsugi ; obasamitsugi. A blind, stubbed,

housed, rabbeted, oblique, scarf joint. The shippasamijoint has a T-

shaped tenon and mortise and the two members to be joined areslipped in from the side. A pin komisen is inserted into a 15mm

square hole at the center of the joint to hold it securely. The tenon

and mortise are not visible from the sides of the joint but a fine,

straight line is discernible. This is the chief difference between the

shippasamitsugi and the kanawatsugi joint. This joint is used to

connect beams and foundation footings.

Figure 3.3 Shippasamitsugi

Image: S.Azby brown


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its use is in fixing boarding

around an octagonal column of

brickwork. Image: Terrie, Nall

1.Tongue-And-Groove

The tongue and groove joints offer a means of

registering the joint edges during assembly. They are

often used without any glue, allowing the boards to

expand and contract without any negative effects.

The joint is formed by having one piece having a

groove, or slot, cut the length of the edge. This

groove is most often one third of the wood's

thickness and is placed in the centre of the edge,

producing two walls of wood that are the same

thickness. The other piece has the sides of the stock

removed, leaving a tongue that is precisely the width

of the groove formed on the first piece.

The recommended length of the tongue depends on

the width of the stock used to form the panel. For

panels formed with stock less than 3 inches wide,

the tongue length is not that much of a factor. For

these panels, the tongue only needs to be as long as

they are thick. This will produce a tongue thatappears square when viewed from the end. For

panels that are formed with wider stock, it is

recommended that you make the tongue's length at

least half the stock's thickness.

The groove should always be slightly deeper than the

tongue is long, by as much as 1/16" for 3-inch wideboards. The reason for this is two-fold. First is to

prevent problems during assembly. If the tongue

length is cut exactly to the groove depth, then the

slightest piece of sawdust or imperfection in the

wood will keep the two pieces from mating properly.

The second is because of the effects of seasonalexpansion and contraction. If one panel expands at a

slightly different rate than its neighbour, the tongue

from one piece can actually push its neighbour away,

and break the joint.

Note: tongued and grooved

joint suitable for edge or

end jointing, such as fitting

matchboarding round a

chimney breast, making

small jewel drawers, etc.

Image: Terrie, Nall

Figure 1.

Tongue-And-Groove

Image: Terrie, Nall

This figure shows a tongued

and grooved joint with a bead

worked on same to hide the

joint, sometimes called a

staff-bead. It would be usedin positions such as boarding

around an upright iron pillar,

etc., the bead giving a neat

finish at each corner.

Image: Terrie, Nall


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When all the tongue and groove boards in a panel are assembled, there is

often a slight difference in height between the panels, or the panels may

separate slightly due to seasonal changes, and that can produce an effect

that is undesirable for some people. In those cases, you can add a tiny bevel

on the edge of every board. This will produce a v-groove effect between each

board, and it will camouflage the uneven height, at the expense of having avisible groove.

Methods

One of the following woodworking tools may be used to produce the tongue

and groove:

A four- or six-head moulder (for large quantities)

A spindle moulder (wood shaper)

A circular saw bench

Suitable hand planes: a plough plane for the groove and a tongue plane for

the tongue, or a combination plane

A spindle router

A table saw

Where used

The tongue-and-groove joint is often used to form wider panels from

narrower boards, such as when forming table tops, doors, or architectural

panelling. Its also widely used for strip flooring.

Historically, the tongue-and-groove joint was also used to register and align

the edges of vertical panelling in early homes. In this application, the joint

allowed for seasonal expansion and shrinkage of the individual boards whilecreating an airtight wall.

By hand or machine

Historically, the joint was cut with matched wooden planes. These planes

were sold in pairs (in sizes designed to work material ranging from 1/4 in. to

1-1/2 in. in thickness). One plane would cut the groove, and the other would

cut the tongue.

In todays small shop, the tongue-and-groove joint is most often milled with arouter or router table fitted with a pair of matched bits. The matched bits

work much like the old wooden planes, only faster and with less effort. This

joint can also be produced on the table saw


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How to Make Tongue and Groove Joints

Step 1: Cut the Groove

When cutting joints, make sure the router

table is clear of sawdust. The debris under

the wood can cause the cut to be

misaligned. The tongue-and-groove bits are

a matched set. The smaller bit on the right

cuts the groove. The larger bit cuts the

tongue. Washers can be used to adjust the

size of both bits if needed. Put the groove

bit in your router table and set up the cut.

An indexing line on the bit shows you where

the two plates match together so you canlocate the centre of the cut.

Step 2: Cut the Tongue To make the

matching cut, use the bit for cutting the

tongue. This pass removes a large amount

of material, so take it slowly. The two pieces

should fit together to form a nice joint.

Step 3: Use a Straight Flute Bit to Cut the

Joint (Optional)

Specialty tongue-and-groove bits make easy

work of creating the joints, but they can be

a bit expensive. If you dont have the budget

for those bits, a simple straight flute bit can

be used to cut a tongue-and-groove joint.

The same bit can be used to cut both pieces

of the joint. Cut the groove first. Set thefence on the router table so that the bit will

cut approximately through the center of the

board. Turn the board around and make

another pass. The board now has a cut

through the center. For the tongue, move

the fence forward so that youre cutting

away the edges of the board. Your goal is to

leave the same amount of material on the

tongue board as you cut away on the groove

board. This will take at least two passes.

Once the cuts are made, put the boards

together to get a tongue-and-groove joint.All Images: http://woodworkbasic.com
http://img.diynetwork.com/DIY/2005/11/14/dit339_2ff_lg.jpghttp://img.diynetwork.com/DIY/2005/11/14/dit339_2fb_lg.jpghttp://img.diynetwork.com/DIY/2005/11/14/dit339_2fc_lg.jpghttp://img.diynetwork.com/DIY/2005/11/14/dit339_2fe_lg.jpg


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Figure 1.1 : It is a section of flooring

which is generally made of hardwood,

such as maple, oak, or jarrah. It is

used in positions such as ballroom

and skating rink floors, etc

The tongued and grooved joint is used in one form or another throughout the

whole of the woodworking trades, covering, as it does, a great variety of work

from the laying of flooring boards to the construction of dressers, bookcases

and other cabinet work.

Flooring and match boarding generally have the tongues worked on the solid

board, and examples of a few of the various types are shown as follows:

1.1 : Tongued and Grooved Flooring Board

It used in the construction of floors for mills,

workshops and cottage property. This type of

flooring is nailed to the joists in the ordinary

manner, no attempt being made to concealthe nails used .(Figure 1.1 )

the tongue and groove being worked in such

a manner that the joint covers the nails as

shown. Each nail is driven into its position at

One edge of the board, the groove holding

the next board and hiding the nail (Figure 1.1.1)

1.2 : Tongued and Grooved Matchboarding

1.2.1 Tongued, Grooved and Beaded

It is used for nailing on framing to form

partitions for rooms, etc., for panelling

corridors, etc., and for making framed and

ledged doors, building tool houses, cycle

sheds and other outhouses.

The object of working a bead or beads on

matchboarding is to break the jointing of the

various pieces and to aim at ornamental effect;

also to prevent unsightliness should the timber

shrink slightly. When a moderate amount ofshrinkage takes place, as is nearly always the

case, the joint at the side of the bead appears to

the casual observer to be the fillet or channel

worked at the side of the bead.

Figure 1.1.1 Tongue and groove

joint for nailing

Figure 1.2.1 Tongue and

groove joint with bead

All Images: WILLIAM FAIRHAM


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1.2.2 tongued, grooved and veed

These are used for similar purposes to

Tongued, Grooved and Beaded joint, and

many prefer the V matchboarding variety

because it is more easily painted than the

beaded variety.

1.2.3 Double tongued and grooved

used in the wholesale cabinetfactories. It is preferred for the

jointing of cabinet stock, and the

amateur can make a similar joint by

working two grooves and inserting

loose tongues.

1.2.4 Dovetail Tongue and

Groove

The dovetail tongue tapers

slightly throughout its entire

length, gripping the joint on the

principle of the wedge and

squeezing the glue into the

pores of the wood.

Left : Figure 1.2.4 Dovetail Tongue and

Groove

Top : Figure 1.2.4.1 Double dovetailed

tongue and groove joint

Figure 1.2.2.1 Tongued Grooved and

Veed joint chamfer

Figure 1.2.2.3 Tongued Grooved and

Veed joint radius with bottom

Figure 1.2.2.2 Tongued Grooved

and Veed joint radius

Figure 1.2.3 Double tongued and

grooved joint



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1.3 Tongued and Grooved Mitre

Figure 1.3.1 shows the method ofworking the groove in the above

joints. The pieces are turned back to

back, the mitres thus making a right

angle. The guide on the grooving

plane thus works against each face

of the joint, and this ensures correct

jointing. Figure 1.3.2 is somewhat

similar but with a quarter circlemould to hide the joint.

Figure 1.3 Tongued and Grooved Mitre

Image: Terrie, noll

used for strengthening the corners

of cabinet work, such as tea caddies,

small boxes, plinths, etc. Two pieces

of wood are glued in position andallowed to set prior to glueing and

cramping the joint proper. These

pieces are afterwards planed away,

thus leaving a clear surface to the box

sides.

Figure 1.3.1

Figure 1.3.2

This Figure indicates the building up of a double skirting

mould. C represents the brickwork, A the oak-framed

panelling, and B the packing and fixing block. A wide skirting

of this type is made in two portions for convenience in

working the moulding and to prevent undue shrinkage.

Image: Terrie, noll

Image: Terrie, noll

Ploughing.When grooves have to

be worked in the edge or face of a

board to receive tongues, the process

is generally called ploughing, and it is

usually accomplished by a special tool

called a plough


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2. Birdsmouth joint

In light frame construction, abirdsmouth joint is a woodworkingjoint that is generally used to connect a

roof rafter to the top plate of asupporting wall. It is an indentation cutinto the rafter which consists of a "seatcut" (the face of which rests on the topplate) and a "heel cut" or "plumb cut"(the face of which lies parallel to thesupporting wall), forming a shaperesembling a bird's mouth. Theindentation should not be too deep

(less than a third of the rafter'sthickness) in order to maintain thestructural integrity of the rafter. Thejoint is generally fastened with nails.And it is used a lot for permanentpropping of under purloins in roofs andfor temporary propping in formworkand shoring work.

Figure 2.Birdsmouth jointNote: A birds-mouth joint in a rafter, set

upon a double top plate. Shown are the two

cuts of the joint: the seat cut and the heel

cut.

Figure 2.1.Birdsmouth joint

Note : The sketch above shows the

centre lines of the two members lining

up, and this works in most cases. It is a

good rule of thumb that makes sure that

the small lip is never so small that it can

split off under load and let the prop

slide. Usually fixed with nails in

temporary work

Left : Figure 2.2

birdsmouth joint.

NOTE: It can be

readily made by the

handsaw, used when

a spar fits on the wall

plate. A nail is shown

securing it in position.

Right : Figure 2.3

shows the

birdsmouth joint

where the spar runs

over the outside of

the wall plate, thusallowing a fixing for

an ornamental finish

All Images : William Fairham
http://upload.wikimedia.org/wikipedia/commons/e/e8/BirdsMouthJoint.jpg


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Instructions

1. Angle the blade of yourtable saw at 45 degrees when

you prepare to cut a birdsmouth joint.

2. Position the fence of your table

saw so that the board will be almost

the board's width away when you

cut a birdsmouth joint. This way, you

will save yourself the possibility of

the waste getting trapped between

the board you are cutting and the table

saw's fence.

3. Take your first board and guide it along the fence until you are able to

get the depth you wish. This depth will depend on the thickness of the boards

and the column you are building. You will find that the depth of the blade willmatch the board's thickness.

4 . Repeat the process with the rest of the boards.

5 . Turn the first board over and place it on the table saw.

6 . Adjust the blade downwards about halfway, and adjust the fence of the table

saw of an inch to the left.

7 . Cut the board again, moving the fence to the left as you cut. Continue doing

this until the bottom of the birdsmouth joint, or the bird's beak, is flat.

8 . Continue doing the same with all of the

boards when cutting birdsmouth joints.

Figure 2.5 Adjustable roofing protractor

The tool with particular application to

setting compound angles. The Tool is a 3

dimensional protractor, all the angles are

converted to degrees

How to Cut a Birdsmouth Joint

Figure 2.4 the rafter birds mouth cut

can't be any more than 1/3 the rafter

depth.

Image: Jim rogers


19/54

This figure shows the two components of

the rafter, the main roof triangle, and the

eaves triangle. You need them separated

(mark them separately), to get your birds

mouth line.

If you are fixing timber fascias, leave the

bottom of the rafter uncut, and cut it off

after the roof is finished to a string line.When using a metal fascia with pressed

metal clips that are nailed to the ends of the

rafters, cut your fascia cuts on the ground,

because the clips can take up any small

discrepancies.

Figure 2.6 : Note : Cutting a birdsmouth ona roof depends on the pitch angle of theroof. Looking at the image on the right youcan see a horizontal line drawn above thebirdsmouth cut. The angle between thisline and the face of the rafter (i.e. the topface of the rafter where the roof tiles willbe laid) is the same as the angle at whichthe roof is pitched. Drawing a line 90degrees down from this line gives you thevertical cut which sits at the front of thewall plate. In the case of a 30 degreepitched roof, the angle between thevertical birdsmouth cut and the undersideof the rafter, is 120 degrees.

The purpose ofthe birds mouth is to

allow the rafter to sit easily in the correct

position while fixing. If the rafter was

fixed without a birdsmouth the carpenters

fixing the rafters would have a hard time

stopping them sliding downhill while

nailing them into place.Using metal framing anchors or bolted

connections there is no reason to have

the notch cut out provided that there was

some way of holding the rafters accurately

in position while fixing them. In normal

framed roofs it is a general rule that the

notch should be no more than 1/3rd the depth of the rafter.

All Images: Jim Rogers


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LapJointThere are two categories of lap joints in existence the full and the half

and both of these are used in a slightly different way. The full lap joint is

contrasted from the half-lap in the amount of material that is used to make

the joints. Different types of these joints are used in framing and in cabinetry.

In addition, variations on the joint exist and include the cross, the dovetail,and the mitred.

If two pieces of wood are joined without any material being removed, a

joiner will have made a full lap joint. The thickness of this joint will be the

sum of the thickness of both wood pieces. A full lap requires fasteners in

order to stay together and offers no resistance to racking. However, it does

partly resist twisting and shearing. This joint can be used in temporary

framing and in the construction of some timber frames.

In a half lap joint, material is removed from each of the members so that the

resulting joint is the thickness of the thickest member. Most commonly in

half lap joints, the members are of the same thickness and half the thickness

of each is removed, A half-lap joint can be reinforced by dowels or by

fasteners. It offers some resistance to racking and, when it uses fasteners, to

twisting and shearing.

3 Half joint

A half lap joint is where two pieces of stock, which are typically of the same

thickness, have half of the material removed so that the two boards fit

together so that the joint adds no thickness at the joint. These joints work

well for right-angle connectionsUse for :

Frame assembly in cabinet making

Temporary framing

Some applications in timber frame construction

There are many ways to cut half lap joints and the method employeddepends on the size of the stock. For larger projects where the stock is at

least two inches in either direction, use table saw with a stacked dado set.

For smaller stock, a router table works well.

Figure 3.1 Half lap joint terminology


21/54

How to Make half lap Joints

Step 1: Trace the Lap

Using a pencil, trace the lap on eachpiece of wood. The lap should be half the

thickness of the wood and two to four

times as long as the wood is thick. It's

essential to measure so that the laps on

both pieces of wood have identical

dimensions.

Step 2: Set the Table-Saw Blade

Set a table-saw blade at exactly half the

thickness of the first strip of wood. In this

case, For example if the pieces of wood

are 2" x 4" lumber, whose thickness is

actually 1-1/2", so the saw blade is set at

a height of 3/4".

Step 3: Cut the Wood, and Create an L

Shape

Pass the wood through the blade, starting

at the innermost edge of the lap . Make

as many passes as needed, working the

blade toward the end of the work piece.

Eventually you'll create an L shape in the

wood.

Step 4: Secure the JointRepeat steps 3 and 4 for the second piece

of wood. The two laps should be a

perfect fit. Fasten the joint with glue.

Secure the joint with wood screws.

When to Use Half Lap Joints:

The half-lap joint can be quite strong

when properly used. However, be

advised that thin pieces of stock may be

weakened by removing half of the

material to accommodate the joint, so

use this connection only when the stockis thick enough to maintain the

structural integrity of the board after

half of the material is removed.

All Images :http://www.sawdustalley.co.uk/
http://img.diynetwork.com/DIY/2003/09/18/t163_3fc_lg.jpghttp://img.diynetwork.com/DIY/2003/09/18/t163_3fb_lg.jpghttp://img.diynetwork.com/DIY/2003/09/18/t163_3fa_lg.jpg


22/54

Figure 3.2 : shows the elevation of an imaginary frame which is indicated as made up of

a number of halving joints; it shows also the application of the various joints to this class

of work. Each joint used in the construction of this frame may be dealt with separately.The numbers marked on Fig. 1.2 refer to the individual joints, shown separately in Figs.

1.2.1 to ...

Figrue 3.2.1 :Corner half lap joint(see Figure 3.2, 1). Each piece is halved

and shouldered at opposite sides, thus

forming a perfect fit one with the other

and giving a strong joint with a minimum

amount of labour. For inside work the joint

would be glued. For outside work,, the

alternative method of smearing the joint

with paint or with a mixture of varnish and

white lead would be advisable, the joint

being nailed or screwed.

Figure 3.2.2 T half lap joint

(see Figure 3.2, 2). It may be used in nearly

all cases where a top or bottom rail runs

through an upright.

Figure 3.2.3 Oblique halving joint with

Shoulder

(see Figure 3.2, 3). This type of joint is

used for strengthening framings and shelf

brackets. A strut or rail of this typeprevents movement or distortion to a

frame diagonally.

Figure 3.2.4 Oblique halving joint.(see

Figure 3.2,4) It used in similar positions to

Figure 3.2.3, and has in some cases the

disadvantage of showing end grain at the

top of the frame.



23/54

Figure 3.2.5 Dovetailed Half Lap

Joint.(see Figure 3.2,5)

The dovetailed half-lap improves upon

the design by preventing the lap from

being pulled out due to the dovetail-

shaped lap. To create the joint, first

create the end lap one board and trim

the cheeks to a dovetail shape. Once

done, simply transfer the shape to its

mate and notch it accordingly.

It used in similar positions to Figure

3.2.3, and has in some cases the

disadvantage of showing end grain at

the top of the frame.

Figure 3.2.7 Halved Joint with Double

Dovetail.(see Figure 3.2,7) the pieces at

one end showing a double dovetail. This

particular joint is seldom used except

for Manual Training

Figure 3.2.6 Mitred half lap.(see Figure 3.2,6)

This is a variation of the end lap which shows

a mitre on the face of the finished work.

The mitred half lap is the weakest version of

the joint because of the reduced gluing

surface.

Use for:

Visible framing applications where a mitred

corner is desired

It used in similar positions to Figure 3.2.3,

and has in some cases the disadvantage of

showing end grain at the top of the frame.

Figure 3.2.8 Halved Joint with one sideDovetailed.(see Figure 3.2,8) This joint is

used in similar positions to Figure 3.2.5, and

rather less labour is required in the making.

Figure 3.2.9 Oblique Dovetail Halving.(see Figure 3.2,9) one

side of the piece being dovetailed. The joint is used toprevent racking, and as a cross brace to framing. It is

occasionally made with both its sides dovetailed as shown at

Figu8re 3.2.5.



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Figure 3.2.10 Stopped dovetail half lap

joint

(see figure 3.2,10) In this joint the dovetail

is similar to Figure 3.2.5, with the

exception that it does not run through the

bottom rail. This is an advantage if thebottom edge of the rail is in evidence, or if

it is required to glue a moulding or

hardwood facing slip on the lower edge.

The glue adheres better with the grain

than it would end way of the grain, and if

slight shrinkage occurs across the width of

the bottom rail the moulding would not

be forced away by the upright.

Figure 3.2.11 cross half lap joint. It is

lettered B in Figure 3.2 where each piece

runs through the other.

Figure 3.2.12 shows a Tee Halving Joint

with a dovetail cut on the edge. This is

seldom used except as a woodwork exercise

Figure 3.2.14 Halved joint on barrow wheels

we have the application of halving joints

when constructing a barrow wheel. The

centre portion is an example of three pieces

half-lapped or, as it is sometimes called, one-

third lapped. A sketch of the three pieces

separated is shown at L, B, C, Figure 3.2.14.1.

This joint is extensively used in the pattern

making trade for lap-jointing the arms of

pulley patterns, etc. It is probably the most

difficult of the halving joints to mark out and

construct with the desired degree of

accuracy.

Figure 3.2.13 Halved moulded joint

indicate the halving of cross pieces which

have their edges moulded; the pieces are

shown separately, the moulding being

omitted to give a clearer representation of

the method of construction.

Top Figure 3.2.14

Left Figure 3.2.14.1



25/54

Different between Eastern and Western joint

Shape and structure

Abundance and scarcity of timber

European splicing joints were

seldom as impressive as Japanese

versions. When a carpenter in

Europe went out of his way to

design a new joint, in the 19th

century he had to accept being

ridiculed.

European joints are very simple and

strong rather than Japanese one (left Images), Japanese joints are very

decorative but not strong.(Right

Images)

Japanese carpenters have

traditionally lavished as much

attention on the frames of

their buildings as Westerners

gave to their furniture, partlybecause Japanese shrines and

houses have traditionally had

very little furniture. Before

hand-operated power tools

were introduced to Japan in

1943, the Japanese carpenters

tool chest contained 179

items, mostly wood-workingtools. Japanese and Asian

carpenters tend to saw and

plane towards the body rather

than away from it as Western

carpenters do (the Japanese

method are accuracy than

Western method)and

sometimes maneuver aroundthe outside of tall structures

on poles rather than Western-

style scaffolding.


26/54

Different in Protection and prestige

European timber construction without wooden nails (dowels) would

unthinkable. Every scarf, lap or tenon had to be secured to prevent one part

pulling away from its mate. The wooden dowel, although normally hidden

from view.

Traditional Japanese wood structure have few nails .In juxtaposing Japanese

solutions, the very different artistic attitude of the European is proved by the

dilettantish and often seemingly makeshift nature of protective measure on

building.

Different in Protection sill beam

In Japanese end grain had to be hidden. Unattractive things are hidden, i.e.

denying the presence of any constructional problems, became an

increasingly tantalizing challenge for the Japanese carpenter as exposed

surfaces multiplied. Specifying the aesthetic value of not countenancing any

visible end grain demanded even more refined designs on the eaves corners

than it did on the sill corners, a large properties of which were normally

screened by a column (see frig.1).

At the eaves at least two sides were always completely visible, so joints here

were only permitted to exhibit a mitre seam after assembly (see fig.2).

Fig 1. Eaves corner detailEnjo-ji hondo,Nara,Japan(according to:Bunkazai...,1986,p.348/1)

Fig 2. Eaves corner detailon a hipped roof (accordingto: Graubner,1986,p.132)

Japanese carpenters and architects use their skills not decorate wood

surface but rather to maximize the effect of unadorned wooden surfaces.

Variations are made with different woods, grains and finishes. In Japanese

lumberyards, pieces of wood are not piled in big stacks as they are in

Western lumberyard; rather they are organized by color and grain.


27/54

Different in Construction

The focus on creativity shifted appreciably towards decoration-quite

differently in Japan owing to the aesthetic criteria which different from

those in Europe. The products of this shift in emphasis are judged all too

easily as nonsense by European with their modern sense of values.

The renewal of the bases of columns probably made up the bulk of the

Japanese carpenters workload. This gave him the chance to express his

individuality on a daily basis (see fig.3). The viewer is forced to reflect on the

comparison with the European examples of joints, the functions of which

have been left further and further behind. The age of the frivolous

increasingly takes centre stage (see Fig.4)

Fig 5.

Tranferring the functional parts of a joint to the inside

was in no way abandoned with the coming of the

exclusively decorative features on the surface.-

Sumiya,Kyoto.

In Europe the carpenter proudly displayed his wares,

in Japan the carpenter compelled the viewer to look

more closely(see fig.5)

Fig 3.

Column-base joint on the

lmanishi House in Imai

cho,Nara,Japan

Fig 4. Decorative joints

on the Sumiya,Kyoto.


28/54

The carpenter has connected the pieces in a way which, at first sight,

appears impossible. And that is exactly the effect desired by the joints

creator. His attention having been captured, the observe is normally at a

loss to explain the mystery; every colleagues are puzzled by the

seemingly inexplicable (see fig.6). In this way they achieve a vague

justification for their insubordination with regard to the first rule of

aesthetic, i.e. that the position of the joint should remain hidden from

view.

Such puzzles were not unknown in Europe. So called meister witze

(masters pranks) are impossible joints. What makes them possible

is, on the one hand, knowledge of the materials properties and, on the

other, the ability to break free frame from the chains of conventional

ways of thinking.

What began just above the ground become even more noticeable once

placed at eye level, even for the Japanese, despite their very different

relationship with the ground compared to the people of Europe (Fig.7)

Fig 6.

A decorative joint which requires lateral

thinking to solve the puzzle.-Model of the

Takenaqka-daiku-dogu-kam in Kobe,Japan

Fig 7.

The other two sides of this

gatepost are identical their

visible counterparts.-Osaka-

jo otemon,Hyogo,Japan


29/54

Fig .10 in order to incorporate a

ceiling, for instance, battens to

carry the ceiling can be suspended

in this manner. A member fixed

under the roof construction has a

dovetail end which fits into the

batten. Keys are then inserted into

the batten left and right of thehanger and pushed into place

either side of the dovetail to

secure the batten.

Different in Log construction

In Europe one fundamental problem with logconstruction is that the selfweight of the members canadd up to such a colossal figure that the wall threatensto buckle under the load (see fig.8).

In Japan multitude of joints have been developed whichallow members to be incorporated subsequently (seefigs.9,10).

While wind bracing in Europe was based on fixing theangles between members, attained throughtriangulation, the emphasis in Japan was on the maxim

solid and resilient .this leitmotiv in Japanese column-and-beam construction clearly illustrates the reason whydiagonal brace are encountered comparatively rarely.Only in this way could builders achieve the elasticityrequired to cope with the many earthquakes. Thecarpenters obtained stability by way of the revolutionaryintroduction of the tenon which passed right throughthe column (see fig.11).

Fig .8

Bulgin describes

superbly the buckling

of these logs on the

church in Topola,

Slovakia.

Fig .9 the dovetail of the loose tenon is inserted

into the column and pushed upwards. The rail,

erected afterwards, is now inserted into the

column. The protruding end of the loose tenon

slips into the rail and is held firmly in place by

means of a key.

Fig .11 in Japan it is

specified exactly which

tenon should penetrate

the corner column above

and which below. Oneidentifies the

longitudinal direction ,

the other the transverse.


30/54

When the area enclosed by two horizontal

beams meeting at right-angles was too large,

this area had to be halved by adding a future

beam, It is interesting to observe here to what

extent carpenters remained loyal to theirrespective traditions. In Europe they simply

provided a trimmer to pick up the load from the

extra beam and transfer it back to the two main

beams (see figs.12,13).

In Japan they continued to design tension joints

in the manner to which they were accustomed

(see fig.14).

Fig .14

The carpenters of the Kyuan-ji

romon,Osaka,Japan, first secured the main axis

beyond the usual dimension by means of two

dovetailed rebates in order to secure the otherbeams in the intersection using suitably adapted

dovetails. (According to : Bunkazai..., p.306/1)

Fig .12

As this segment from the

octagonal floor of the

lantern at Ely

Cathedral,Cambridgeshire,E

ngland, illustrates, the

system of providing trimmer

beams was a principle which

was certainly common

throughout Europe.

(According to:

Hewett,1985,Figure.113)

Fig .13 By providing a trimmer

between the main beams,carpenters created space for

fixing an additional beam.-

Granary of Ernstbrunn

Castle,NE A ustria


31/54

The function of wood joint

The function of loadbearing structural wood joint in terms of

construction is to join together pieces of timber permanently and

securely in such a way that the required structural interaction of the

constructional element or the construction itself is enabled. There arevarious ways in which we can reach this goal, as a peculiarity of Japanese

timber construction illustrate superbly. What at first sight distinguishes a

Japanese building from its European equivalent is the almost total

absence of diagonal bracing. This is suspected as being one of the reason

why large buildings too have survived severe earthquakes without

suffering more serious damage. To be able to absorb these destructive

forces has always been one of the prime tasks of Japanese wood joints.

Characteristic of many Japanese joints are the lateral shoulders which

embrace the support; these prevent the horizontal member from

twisting which would seriously endanger such a thin tenon. At the same

time, this partial enclosing of the support seems to be its weak point,

caused by the mortise. The reason for using this type of joint was tooffset the lack of straight building timber and to enable construction with

timber of poorer quality. Only at first sight does this appear to contradict

the enormous volume of wood used in building.

Accuracy of fit was no mere ideal in Japanese building. It was the

absolute minimum requirement for everyday practice. The joints

themselves are the best examples of the interplay: the more branches to

the joint, the more accuracy the carpenter had to work. The reverse of

this is that the carpenter would obviously only invest time and effort in

evermore complicated intersections if his work had a practical objective,

if a real improvement in the joint, with its increasing complexity, could be

expected.


32/54

The role of the tools

For examples dovetail joint linking two parallel log walls, the logs with the

dovetail cut in their end grain are not visible externally. They alternate withthe log with projecting ends. The log walls of which connected in an

astonishingly similar manner to the first Japanese ones but do not exhibit

projecting ends at the corners because they were buried and so did not

require the same secure joints.

In contracts, the pectinate European logs formed, via the joints, a self-

supporting three-dimensional object right from the start, while the Japanese

equivalents, without their vertical retaining supports, would have fallen apart.In Japan it is suspected that saws were used in producing tenon as early as

the 7th century. In Europe the frame saw was not put to use until the end of

the 14th century, from it speeded up or simplified the work. This is probably a

correct assumption for most of those areas in which column-and-beam

construction was common, such construction prevailed in the towns where it

was erected by professional carpenters who had recognized the advantage of

saws much earlier and had already put them into use.

The longitudinal and transverse stiffening of a framework by means of rails

and beams was solved very differently by the Japanese in comparison with

their European colleagues. While the latter often only accomplished their

task through the vertical displacement of horizontal members leading away

from columns, in Japan every effort was made to remain in one place (see

fig.15).

Fig.15 in the Todai-ji nandaimon,Nara,Japan,

the solution in 1199 was to treat each member

equally,all parts being weakend in the same

way.(According to:Zairai koho no kenkyu,1993)


33/54

Kawashima describe very small buildings on the

island of Amami Oshima, Japan, whose exposed

position has been taken into account in their

special construction. Limited by inferior tools,framers used extremely long tenons of reduces

width on their columns, onto which all the

horizontal members, provided with corresponding

holes, were threaded cross-wise. That this type of

construction has proved to be worthwhile might

well be attributable to the flexibility of this tenon

(see fig.16), comparing these with the through-tenons of keyed tenon joints, which were in fact

often assisted by kneebraces but still broke, or the

teazle tenons of the columns, which could not

withstand the thrust of the roof loads, it is

interesting to note just how well the builders of

such structures had to know their material. The

Japanese column tenon was not stronger because it

represented a more sophisticated engineeringdesign. Nor was it more durable because the

timber chosen was more suitable.

.

Fig.16 Koune ke jutaku no

otoshi koho: the principle

of the framing in this

construction in koune

House ,Tokushima,Japan,is

based on threading the

horizontal members onto

the variously tapered endof the loadbearing column.

(source:Tsigu shiguchi

kenchiku no kakusareta

chie,1984, p.51)

The influence of climatic condition

The conditions encountered in Japan are not met with in Europe in the

same way. The traditional Chinese tiled roof, from which the Japanese roof

is derived, weights up to four times that of a modern European roof. The

frequent earthquakes and the typhoons with hurricane-like rainfall

represent a challenge which could not have been tackled by simply using

the unaltered Chinese system. Besides constructional modifications, the

Japanese carpenter also decided to adapt the joints, seen in this right,

statements contrasting the most technically advanced and ingenious

Japanese joints whit those of central Europe, which are weather-resistant

and capable of carrying heavy loads. (In Japan condition such as high load-

carrying capacity were occasionally regarded as being of secondary

importance.)A straightforward comparison is problematic because the condition are so

different.


34/54

For centuries, the Haubarg columns carried theirloads without complaint, so long as their inclinationresisted the thrust of the loads. It was only when thistradition was cast aside and the columns places

vertically that elasticity if the tenon was overtaxed. Ifindividual components of an assembly are altered,whether due to thoughtlessness or lack of expertise,that can lead to apparently inexplicable or wronglyinterpreted consequence.

Column which stand directly on the ground sufferfrom the effect of moisture .Renewal of the column

base is required more frequently than any other partof the construction (see fig.17). In such cases bothEuropean and Japanese carpenters relied on tried-and-tested techniques. In contrast, one conspicuousdifferent between Japanese and European solutionswas the complexity of the joint and itsimplementation (see figs.18,19). Furthermore theclimatic conditions in Japan demanded far more

frequent replacements than in Europe (see fig.20).Some wood joints are made unusable by the weather.The angled jointing nail, for example , was both astrong and widely used method of jointing

Fig .20

Does this stone plinth

the temple gate in

Hagi,Yamaguchi, Japan,

express a sense of

weariness or does its

shape perfectly matched

to the rimber reflect a

hearty joviality ?

Fig .17

Renewing the base of

a post to a simplegrain-drying shed in

Kramsach,Tyrol,Austri

a.

Fig.18 renewedcolumn base on the

Osakajo sakuramon,

Osaka, Japan.

Fig.19 The new columnbase of this grain drying

shed from Carinthia in the

Stubing Open-air

Museum,Austria, appears

primitive by comparison.


35/54

Different in nominate

some Japanese joint have More than one (see

figs.21,22)

The lack of identification in some of the names given to

joints appears excessively liberal. For many Japanese

joints, designate exactly the place at which they are to

be incorporated. While in Europe a long name for a

joint lets us suppose a complicated variant, a similar

conclusion would be totally erroneous in Japan. For

example : Zushi-dodai-sumi-shiguchi tells us absolutely

nothing about the complexity of the connection but

instead solely describes where it is ues: the corner

connection of a sill in a small shrine (see fig.23).

The Japanese carpenter made it his business to not

only produce a joint matched to the respective building

task but to also try out a combination of experience

gained and new ideas in every new building of

significance. Just as the names given to some joints

allow us to discern the purpose for which they wereconceived, the joint receives its final accolade by being

build into the structure: in the first case security against

vertical displacement, in the second horizontal.

.

Fig .22 the secret dovetail corner joint, only

used in Europe by cabinetmakers, is to be

found on many Japanese temples and

shrines. In Japan this joint is variously

called kakushi-ari ( hidden dovetail) and

sumi-tome-ari (mitred corner dovetail).

Fig .21

Both joints are calledari-kake,irrespective

of whether they

interconnect flush or

not.

Fig.23 Sill corner detail

Tomyo-jihondo,Kanagawa, Japan

( according to:

ibid.,p.255/1)


36/54

Introduction

the royal botanic garden, established in 1670 as a physic garden, is now a world-

renowned centre for plant science, research and education. the building has beendesigned by Edward Cullinan. the gateway acts as a threshold to one of the worlds

most important botanical institutions and aims to capture the spirit and enthusiasm

of that organisation.

the building combines the practical need for improved visitor facilities with an

opportunity to engage visitors in the work of RBGE and the exploration of the

relevance of plants to the critical issues of our time. thus, as well as office space, a

restaurant, an outdoor caf, a plant sales area and visitor restrooms, the new centrehouses exhibitions and a studio space for demonstrations and exploration into the

world of plants.

Figure.1 The garden terrace and biodiversity

ponds , Image: Paul Raftry Figure.3 InsideImage: Paul Raftry

Figure.2 Outside

Image: Paul Raftry


37/54

Building DescriptionThe Gateway is set on an important crossing of routes and gives wheelchair access

to the central part of the Garden. Most visitors enter through the double-height

entrance foyer, a dramatic space supported by a diagrid of tapering glulam beams

and framing a view of the Garden beyond. The foyer leads into a large exhibition

space with a fully glazed east wall, 60 metres long, which forms a gentle curve toframe views of the new biodiversity garden. At the centre is a helical timber

staircase set in a rooflit atrium where the diagrid roof is again revealed,

oversailing the open-plan first floor restaurant and extending beyond to shelter

the outdoor terrace of the restaurant.

Rather than a traditional front and back layout, the building can be approached

and entered from several directions and from different levels, through the glazed

and permeable faades. In contrast, the service elements of the building are

enclosed in solid external walls of broken-edged, stacked Caithness slate slabs.

The building is on two storeys with an overall dimension of approximately 100

metres x 50 metres. Spans between columns vary between 8 and 6 metres. It

uses 2750 square metres of cross-laminated timber slabs, 226mm thick on the

first floor and 146mm at roof level.

Figure .6

Image: Paul Raftry

Figure .5

Image: Paul Raftry

Figure. 4

Image: Paul Raftry


38/54

Concept DesignThe pre-eminence of the Garden is the conceptual

driver for the design. The Gateway marks the entrance

to the gardens by facing a road to the west (Figure.8).

On the garden side, stepped biodiversity ponds extend

from the glass wallof the exhibition space and blend into the surrounding

landscape.

The glass wall is some 60 metres long and enables the

message of the interpretation delivered within the

building to be extended into the Garden and vice versa

(Figure.7). At first floor, a roof terrace overlooks the

biodiversity pond and garden (Figure.9).

Given the botanical nature of the building, it was

natural that the structure should use timber

extensively. It uses an innovative combination of glued-

laminated timber and cross-laminated timber for its

walls, floors and roof. Although

timber was considered for the

columns, they are made fromslender fabricated steel

elements.

Figure.9

The garden terrace and biodiversity ponds

(Image: Buro Happold)

Figure.8

The building in context

(Image : Edward Cullinan Architects)

Figure.7 The double-height

entrance is glazed to frame

a view of the garden

beyond.

Image: Paul Raftery


39/54

a major requirement for the design was to reconcile these two uses:visitors were to pass through the building into the garden but also to be drawn

into the interior. Moreover, visitor movement was not simply in one direction: the

westerly John Hope Gateway is not the only entrance to the gardens (the east

entrance) and within the garden the serpentine arrangement of pathways means

that visitors exiting through the new gateway could approach it from north and

south as well as east. Unlike the simple front and back character of a classical

gateway like Stones, this is a building with bulk and with four facades.

The architects response to these complex demands was to make a clear formal

distinction between the gateway and the accommodation. The gateway is

expressed as a glass box, fully glazed on both park and garden sides from ground

to roof, like a greenhouse, through which the eye passes with minimum

obstruction from park to garden and vice versa. The accommodation is expressed

as a solid volume, largely timber-clad and orthogonal on the side facing the park

but cut away on the Garden side to create a biodiversity garden, with the contours

of the land thereby inscribed in the curved shape of the plan. Separating the two,

and marking the direction of travel through the gateway, is a long wall more like

a garden boundary than the face of a building built of Caithness slate in

horizontal strata, which on the park side projects as a tower (albeit only two

storeys high) announcing the entrance. Connecting the two is a floating roof

supported on glulam beams and steel columns, its diagonal geometry offsetting

the orthogonal arrangement of the plan and its clever design and engineering,

allowing a mass of daylight to penetrate via an EFTE rooflight and clerestorey

windows to the space below. When seen from the park this roof is visible only in

the glass box, the glow of top light helping to identify it as the point of entry,

whereas on the Garden side the elevation to the accommodation block is fully

glazed, allowing the roof to appear to hover above an effect that is particularly

pronounced at night.

Figure 10.Section

Image: Buro HappoldLandscape Description


40/54

Once inside the glass box, the visitor has to turn 90 degrees, left or right. Left for the

toilets, contained in a characteristic Cullinan drum, clad in slate and topped by a

smaller drum housing the rainwater collection tank; right for entry to the garden via

the visitor centre. Taking this second route, we step into a double-height galleried

hall, slightly longer and higher than a double cube, flooded with daylight fromabove. At the far end a helical timber staircase beckons, drawing the visitor up to the

first floor. This staircase, 1.5 metres in width but splaying to 2.3 metres as it meets

the ground, is constructed of 164mm-deep horizontal layers of Douglas fir. Whether

or not it is, as the architects believe, the first helical structured veneered lumber

staircase in the world,.

1 Foyer

2 toilets

3 reception4 temporary exhibitions

5 permanent exhibition

6 science studio

7 plant room

8 shop

9 outdoor shop

10, biodiversity pools

11 biodiversity gardens

12 performance space

13 service yard

14 education room

15 offices

16 kitchen

17 restaurant

18 VIP room

19 outdoor classroom

20 external terrace

Figure.11 First floor plan

Image: Buro Happold

Figure.12 Ground floor plan

Image: Buro Happold

Inside Description


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From the top of the staircase visitors can cross the cafe and step straight out onto

a large terrace overlooking the biodiversity garden, or return back down the stairs

and across the double-height hall to re-enter the glass box. Either way, they can

then enter the botanic garden and explore its delights, perhaps exiting after a few

hours by one of the paths leading to the John Hope Gateway from different angles.

Approached from the north, the building reads as not much more than a gardenwall; from the south, it appears much more substantial, with the VIP room on the

first floor projecting under the cantilevered roof, the staff and service entrance

below and the wooden steps of the giant outdoor lecture theatre alongside.

Approaching head-on from the east, it appears long and low, tied into the land by

its reflection in the ponds of the biodiversity garden.

Figure.13 North elevation

Image: Buro Happold

Figure.14 South elevation

Image: Buro Happold

Figure.15 West elevation

Image: Buro Happold


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Structure

Materials

The use of timber

As befits a building in the Botanic Garden, the Gateway is made out of natural

materials with low embodied energy, including a predominantly timber structure.Wherever possible the use of Scottish, then British, then European materials werespecified to minimise transport distances to site.

As the building is designed for long life it was important to use durable and stablematerials. Several types of engineered timber were used in the buildingsconstruction:

Glulam timber, used for the primary and secondary beams to the first floor androof, is European whitewood from Sweden, formed into glulam beams by Cosylvain France, using 45mm thick laminations.

First floor and roof decks are of cross-laminated spruce panels manufactured byKLH in Austria. Exposed partitions are also made of these panels.

Douglas fir structural veneered lumber (SVL) from Germany, supplied by Woodtrade, was used for the mullions and transoms of the timber-framed glazingsystem. To maintain a consistent palette of materials, SVL was also used to

construct the helical staircase and major items of furniture such as the receptiondesk and bar. SVL is made of thin veneers of timber (approx 2mm wide), gluedtogether to form large sheets.

Wherever possible the timber has been exposed, with cross-laminated timberpanels forming the finished surface of the ceilings and exposed walls to publicareas.

Vertically lapped, untreated Scottish larch boards fixed on battens act as a rainscreen cladding system that was designed in consultation with TRADA Technologyto ensure it needs minimal maintenance and easy replacement of the boards. The

lap runs in different directions on three overlapping layers, creating differentshadows that draw the eye along the faade.

The helical staircase continues the horizontally layered emphasis of thebuildings design. It is constructed from SVL sheet, cut and bonded together toform solid treads and curved balustrade, and reinforced with vertical steel bars.The staircase drawing was fed into a CNC machine which laser-cut the SVL sheetinto precise pieces, including the holes for the bars and the handrail (the handrailitself was hand-cut).

Use MDF panel for decorate in restaurant Tables in the restaurant were cut from seasoned logs felled in the Garden itself;they join together to form large composite tables in the evenings.


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Roof Structure

The roof, a single horizontal plane about 100 x 50

metres overall , is supported by a series of deep,

tapered glulam beams on which rest cross-laminated

spruce planks covered with insulation, membrane anda sedum blanket. The glulam beams are laid on the

diagonal and the resulting coffered soffit shapes give

an individual identity to the open plan spaces below.

The beams are supported on pencil-thin steel columns

formed of four steel angles a deliberate strategy, as

the architect explains; We wanted this visually weighty

timber roof to appear as if it is floating. (figure.16)

Figure .16

Cross-laminated panels

Spanning between

Glulam beams

(Image :

Buro Happold)

Figure.17 A view of the tapered

glulam beam roof structure

during construction.

Image: Edward Cullinan

Architects Ltd

Particular features of the roof structure are as follows:

Diagonal grid arrangement

Flitch plates allow moment continuity across the

column head detail

Low stiffness of column leads to small moment

transfer from the beam into the column. By reducing

the bending moment, the use of a slender steel rod is

permitted at the top of the column.

As an equal and large lever arm is provided from the

centre of the beam to each fixing, the annular ring of

dowels resists the bending applied to the beam in a

very efficient manner. It also creates a striking visual

effect when contrasting with the orthogonal

arrangement at first floor level.

Connection design to EC5.

Countersunk bolt detail leads to a loss of section,

which affects the local stress in the timber

Great care was taken to ensure that edge

distances complied with the minimum spacingrequirements of EC5

Due to the column heads

being rather flexible in thehorizontal direction, it was

important to provide a stiff

diaphragm action to transmit

lateral loads to the various

concrete walls and cores,

which carry lateral loads

down to the foundations. The

cross-laminated panels are

screwed into the glulambeams and to adjacent panels

to form these stability

diaphragms at first floor and

roof levels.


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Figure.20

Primary structural

elements

(Image : Edward

Cullinan Architects)

Figure.19

Glulam to Cross-Laminated Panel Detail showing adjustment for

finishes thickness (Image : Buro Happold)

The first floor structure of 226mm thick cross-laminated

(KLH) spruce planks rests on the lower set of glulam

beams, 210 x 815mm deep and set in pairs at 6 metre

grid centres.(fig ure.19 ) To achieve a visually discrete

connection, the beams are bolted to steel flitch plates

welded between the angles of the cruciform steel

columns. (Figures 20 and 21 ). This provides continuity

past the columns to help control deflection of the roof

structure. The connections are carefully tailored to suit

their position in the building; for instance the use of

paired glulam beams allows them to be reinforced with

additional steel flitch plates for special situations,

including cantilever ends and in one location, load

transfer of a column that supports the roof but does not

extend to the ground (to create a column-free space for

the educational studio area).

Figure.18 Before installation,

slots are cut into the ends of

the glulam beams to receive

the flitch plates.

Photo: Edward Cullinan

Architects Ltd

Figure.21 Four glulam

beams connect to a

column head with flitch

plates; the bolts are

arranged in circulargroups to reflect

rotational forces.

Photo: Edward Cullinan

Architects


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At the top of the columns,

steel rods receive the

vertical load from the roof.

In architectural terms, this

rod is the opposite of the

classical capital; ratherthan expressing and

celebrating the connection

between column and

beam, the junction is

visually diminished. Being

on a diagonal grid, the

beams meet at the centre

of the rectangular grid.

The steel flitch plates

which are bolted to the

beams are welded to a

steel bar which provides

moment continuity in the

structure and creates a

strong visual location to

the centre of the coffered

slab. While at first floor

the bolts to the column

flitch plates are arranged

in rectangular groups, at

roof level, for visual

reasons and for structural

efficiency, the bolts are

arranged in circular

groups, providing a strong

visual contrast. The

arrangement also helps

visitors understand the

structure; a circular

arrangement indicates a

rotational force or

movement while a vertical

arrangement indicates a

vertical force or shear.

(figure.22 )

Figure.22 Detail (Image : Edward Cullinan Architects)


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Stair

First there were complaints about the

stairs bouncing as folk walked on them.

Then some wooden supporting pillars

were added to reduce the bouncing.(Figure.25). This of course would increase

the stress loading on the parts of the

stairs closest to the supports. In the

centre of the Figure.26 can be seen a

small bit of white sticky tape

Figure.24 The iron hanger on the left

holding up the top landing is half of the

structural strengthening to stop the

bouncing Image: Paul Raftery

Figure.25 Wooden props were added

to it temporarily while the problem

was considered. It then developed

some cracks in the side wall at a point

of minor inflexion close to a support

point where the stresses would beconcentrated, and was closed to the

public. Image: Paul Raftery

Timber staircase In the atrium makes a

sculptural addition to the space

(Figure.23). It integrated light in an eye-

catching way to accentuate the spiral

form. LED strips of light, embedded intothe timber treads, simultaneously light

both the tops and undersides of the

steps. The effect is of a seamlessly

crafted object.(Figure.24)

Figure.23

(Image : Edward


Figure.26 crack on stair

(Image : Edward



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Cladding and Glazing

The glazing system was encloses the building,

whilst maintaining strong expression of the

structure. This was achieved through the

connection of timber mullions to thestructure at the column positions. The glazing

system is by Seufert Niklaus and the SVL

(Structural Veneered Lumber) was supplied

by Woodtrade of Germany. (Figure 27)

The building is clad with vertical boards of

Scottish larch (Larix decidua) sourced from

Russwood timber in the Cairngorms,

shiplapped in a vertical manner. (Figure 28)

Figure .27

Glazing mullions, showing the detailing that

maintains visual expression of the steel

column and timber structure (Image : Buro

Happold)

Figure .28 Larch cladding

(Image : Buro Happold)

Figure.30 Close up of the timber used to clad

the external walls.Image: Edward Cullinan

Architects Ltd

Figure.29 A series of Douglas fir SVL

mullions support the frameless glazing

system. Image: Paul Raftery


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Fire Resistance and Timber Surface Treatment

The timber beams and slabs have inherent charring resistance. The Scottish

Regulations only require that the first floor has a fire rating and no special

measures, other than intumescent paint to the steel structure, were required to

achieve this.In the UK, it is a normal requirement of the regulations that large areas of timber

be treated to achieve a spread-of-flame rating to their underside.

Before specifying the finishes to the timber, the Architects visited projects to

examine weathering, noting that some fire retardant treatments colour the

timber orange after long exposure to UV light. They tested possible finishes

identifying one that would give a good white finish and show grain of the timber.

The following summarises finishes chosen:

INTERNALLY - KLH walls, (stained): Sikkens Cetol stain, then, to achieve class

1 surface spread of flame, Envirograf fire retardant varnish

INTERNALLY - Glulam beams: Buro Happold fire engineers (FEDRA) prepared

a Technical Justification Report, which was accepted by the building control

approval body, after discussions with the Scottish Fire & Rescue Advisory Unit.

This showed the fire (flame-spread) treatment to the Glulam beams to be

unnecessary.

EXTERNALLY- KLH soffit: Clear Sadolin quick drying wood preservative, and

top coats Sikkens Cetol white stain

EXTERNALLY- Glulam beams under soffit (clear): All of the external glulams

were treated with externally suitable, clear treatment of Dulux Weathershield

Naked Wood.

EXTERNALLY- Glulam edge beams (white & clear): As these beams receivemore UV/weathering, The Architect specified a stain (the same finish as the

external KLH external soffit shown above).


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Sustainability

A sustainable, low-energy, minimum-waste approach to the buildings design was

part of the message the Garden wished to convey to its visitors. The Gateway has

many demonstrable environmental solutions including the extensive use of

timber; they include a biomass boiler, a green roof, rainwater harvesting, a wind

turbine, photovoltaics (include 11m2 photovoltaic array,), solar collectors for hot

water(15m2 solar thermal panels), natural ventilation and passive night-time

cooling. The sedum roof reduces heat gain to the building in summer, slows down

rainwater run-off and provides an extra blanket of insulation. The design of all

these elements is explained in the permanent exhibition on the ground floor of

the Gateway and this engagement with the public is an important contribution to

the project.

The building is kitted out with all the standard eco-devices and features. But more

importantly it uses materials that are appropriate to its location, especially timber

in various forms, for both structure and finishes. Above all it feels like a building

that belongs to its site and purpose. Some may feel that the device of the glass

box is made to work too hard, with the expectation set up by the eye not being

borne out by experience, but this is countered by the sheer delight of the

architectural promenade thereby established. By careful attention to site,

topography and materials Edward Cullinan Architects has created a building thatwill adorn the city.

Exterior lighting

Outdoors, the rough slate walls are uplit to reveal their stony texture with deep

shadows and highlights. The exterior lighting was carefully focussed to minimise

light pollution important in an area of unspoiled natural beauty. Energy-saving

controls and sensors are also used throughout the project.

The main entrance lobby is an unheated buffer space with abundant daylight for

the plants. Services for heating, hot water and power are hidden underneath the

slab with more service routes integrated at high level.


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Turbine

the wind turbine can produce, at peak, 6 kw of energy, and

contribute to the power supplying the building.

That will contribute the intermittent power supply of about

twelve 100 watt lightbulbs.(Figure.33)

This building has extended its 70 acres of

spectacular greenery with 1400m of plantsexpertly installed at roof level - the crowning glory

for a new visitor centre.

The project was completed using the versatile

Diadem green roofing system and Alwitra single ply

waterproofing membranes supplied by ICB

(International Construction Bureau) Ltd, the UKs

leading supplier of sustainable roofing. Completed

in June 2009, it offers a long lasting and eco-friendlycover for the 15.7 million development.(Figure.32)

Royal Botanic Garden, is the world renowned centre

for understanding, protecting and preserving plants

for a sustainable future. (Figure.31)

Figure.31 The sedum roofprovides

natural insulation for the

building. Image: paul Rftery

Figure.32 Green roof Image: Buro Happold

Figure.33 Turbine

Image: Buro Happold

The Gateways roof will aid the environment

in a variety of ways, stimulating local

biodiversity and oxygenating the air. It will

also help to combat climate change by

providing natural air conditioning - the earth

roof cools the building in summer andprovides high grade insulation in winter. This

also lessens the impact of thermal shock on

the structure and other forms of stress on the

roof.

As well as controlling temperature, the soil

reduces the need for drainage by absorbing

rainwater, minimising harmful runoff andlimiting the risk of water damage to the

building.


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The Gateway has many demonstrable environmental solutions including the

extensive use of timber; they include a biomass boiler, a green roof, rainwater

harvesting, a wind turbine, photovoltaics (include 11m2 photovoltaic array,),

solar collectors for hot water(15m2 solar thermal panels), natural ventilation

and passive night-time cooling. The sedum roof reduces heat gain to the

building in summer, slows down rainwater run-off and provides an extra blanket

of insulation. The Gateway is predicted to achieve Rating A on its Energy

Performance Certificate.

Conclusions

A clear concept remained a consistent driver of design from the competition

through to the completion of the building. However it was hard to maintain this

clarity. Many of the details appear to be simple, but the variations in a building

of this shape, which is moulded to fit the contours of the landscape of the site,lead to many permutations of the standard details.

The final building maintains clarity in the expression of the structure,

particularly in the use of timber. Success in projects of this type can only be

achieved by close integrated working of the design team with the Client,

contractor and specialist sub-contractors.

Given the botanical nature of the buiding, it was natural that the structure

should use timber extensively. It uses an innovative combination of glued-

laminated timber and cross-laminated timber for its walls, floors and roof.

Although timber was considered for the columns, they are made from

slender fabricated steel elements.

visitors can pass through the building into the garden but also to be drawn

into the interior. Moreover, visitor movement was not simply in one

direction: the westerly John Hope Gateway is not the only entrance to the

gardens (the east entrance) and within the garden the serpentine

arrangement of pathways means that visitors exiting through the new

gateway could approach it from north and south as well as east.


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Reference, Traditional joints

1.Klaus Zwerger, wood and wood joints-building traditions of European

and Japanese, Birkhause publishers for architecture .Basel. Berlin.

Boston.ISBN 3-7643-6333-9

2.William Fairham, The Wood workers Series- Wood works joint,

Philadelphia and London J. B. Lippincott Company, 1921

3.William Fairham, The Wood workers Series- Wood turning,

Philadelphia and London J. B. Lippincott Company, 1921

4.Gary Rogouski, The complete illustrated guide to joinery, Distributed by

publishers group West. 2002

5.Terrie Noll, The joint book-The complete guide to wood joinery, Chart

well book, 2006

6. Terrie Noll ,The Encyclopedia of Joints & Jointmaking, RD Press

publication, 1997

7.Richard Harris, Discovering Timber-framed building, Shire publications

LID. ISBN 0 74780215 1

8.Kiyos Seiko, The art of Japanese Joinery, Weatherhill publication, 198

timber form & construction 1

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