optimum value engineering & integrated design

Optimum Value Engineering&

Integrated Design

OVE/ID

Background● OVE/ID is little more than applied common sense.

● OVE/ID concepts are not new, in fact they have been in use by some builders for three or four decades.

● Fits nicely with the “House As A System” philosophy

New technology???T. Eaton Co. mail-order houses which used 24” o/c spacing forthe wall studs (circa. 1920).

Optimum Value Engineering (OVE)

What Is It?● Can be defined as a construction philosophy in which components and systems are designed to meet their intended objectives without excessive or unnecessary use of resources.

● In practice, most houses (both new and existing) are over-designed relative to what is required by the National Building Code – especially from a structural perspective.

● Thus, money is expended without any corresponding benefit.

24 members to protect a plumbing chase??

Integrated Design

What Is It?● Can be defined as a design approach in which all design requirements are considered simultaneously rather than sequentially.

● This permits their competing design requirements to be better balanced.

● Parallels the famous “House As A System” philosophy used by the R-2000 Standard.

OVE/ID

OVE/ID Measures Fall Into Three Categoriesa) Framing measures

b) Mechanical system measures

c) Overall design measures

OVE/ID

a) Framing Measures 1. Design the house using 600 mm (24”) modules for the walls, floor and attic framing. Since most board materials (drywall and sheathing products) are also based on this dimension, wastage is automatically reduced.

Design Using A Modular 600 mm (24”) Layout

OVE/ID

Framing Measures (con’t)2. Align the structural loads for the attic, walls and

foundation which permits direct transfer of loads and allows unnecessary framing materials to be eliminated.

Align The Structural Loads

OVE/ID

Framing Measures (con’t)3. Coordinate wall openings with the basic 600 mm (24”) dimension thereby reducing the number of studs, cripples and other components

Coordinate Openings With The Modular Layout

HOT2000 Can Model The Benefits OfMany OVE Framing Techniques

OVE/ID

b) Mechanical system measures - Aligning mechanical systems to avoid unnecessary runs - Designing the mechanical system based on need rather than historical practice

c) Overall design principles- Optimizing window selection

Benefits Of OVE/ID

● Lower construction costs – more intelligent design results in lower costs.

● Reduced wastage of framing materials creates environmental benefits.

● Reduced heat loss – reduced use of framing materials means fewer thermal bridges.

Disadvantages Of OVE/ID

● More careful design practices are required (more thought).

● Better site supervision is required – at least initially.

● Potentially negative homeowner perception – “less wood means cheaper construction??” – NO! OVE means “more insulation” not “less wood”.

OVE/ID Measures

a) Framing Measures1. Exterior wall framing at 600 mm (24”) o/c2. Floor framing at 600 mm (24”) o/c 3. OVE framing4. Optimum joist length and beam location5. Elimination of floor system cross-bracing6. Support of non-load bearing partition walls7. Drywall clips at corners8. Non-Load Bearing partition walls9. Coordinated framing for windows and doors10. Elimination of lintels in non-load bearing walls

OVE/ID Measures

b) Mechanical System Measures11. Simplified plumbing stack venting12. Core distribution for forced air heating systems

c) Overall Design Principles13. Optimized window selection

Background● The vast majority of Canadian houses use 400 mm (16”) o/c stud spacing for exterior wall construction.

● This exceeds the NBC requirements – 400 mm spacing is only needed structurally required when the wall is supporting two or more floors.

● Why? (“Cuz that’s how we’ve always done it.”)..

1. Exterior Wall Framing At 600 mm (24”) o/c

OVE/ID Alternative● Use 600 mm (24”) o/c spacing unless narrower spacing is structurally required.

● Use wider insulation batts to fit the wider wall cavities.


Advantages (to the builder)● Reduced labour and material costs (eliminates 1/3 of all wall studs).

Advantages (to the homeowner)● Reduced thermal bridging meaning fewer building envelope problems.

● Energy saving: average of 225 kWhe/yr (worth $11 to $22 per year).


Cost Savings● Typical new house: $270, assuming 13 mm (1/2”) drywall is used.

● If 16 mm (5/8”) drywall is used to reduce deflection, then savings are reduced to about $44 per house.

● Material savings, per floor (imperial units) = (0.25) x (wall perimeter, ft) x (stud cost) - [(0.031) x (wall area) x (insulation cost / ft2)

Material savings, per floor (metric units) = (0.82) x (wall perimeter, m) x (stud cost) - [(0.031) x (wall area) x (insulation cost / m2)]

● Labour savings = 1.2 x (material savings)


Background● Structural requirements for floors are largely dictated by the need to control vibration, improperly designed floors tend to be springy.

● However, some builders automatically use 400 mm (16”) o/c spacing when 600 mm (24”) would meet code requirements.

● Structural requirements for dimensioned wood floor systems are defined in the “Span Tables” of the NBC.

● If an engineered floor system is used (wood I-joists, wood or metal web systems, etc.), then design to the manufacturer’s recommendations.

2. Floor Framing At 600 mm (24”) o/c

OVE/ID Alternative● Frame dimensioned wood floor systems with the floor joists spaced 600 mm (24”) o/c, if permitted by the NBC Span Tables.

● Generally not applicable to house which use engineered floor systems.

● May require a thicker sub-floor, which reduces the savings by about 25%.


Advantages (to the builder)● Reduced labour and material costs.

Advantages (to the homeowner)● Energy saving: none.


Cost Savings● Typical new house: $450, if sub-floor thickness is unchanged. $320, if thicker sub-floor is required.

Case 1 – Sub-floor thickness unchanged● Material savings (imperial units) = (0.25) x (floor area, ft2) x (joist cost per foot)

Material savings (metric units) = (0.82) x (floor area, m2) x (joist cost per metre)

● Labour savings = (0.47) x (material savings)

Case 2 – Sub-floor thickness increased● Material savings (imperial units) = (0.25) x (floor area, ft2) x (joist cost per foot) – (0.094) x (floor area, ft2)

Material savings (metric units) = (0.82) x (floor area, m2) x (joist cost per metre) – (floor area, m2)

● Labour savings = (0.72) x (material savings)


Background● This ties measures 1. and 2. together with roof trusses spaced 600 mm (24”) o/c to permit direct load transfer.

● This allows the second top plate to be eliminated but requires metal connectors to tie in the partition walls.

● Major issue is the availability of pre-cut 2.39 m (94 1/8”) wall studs.

3. OVE Framing

OVE/ID Alternative● Align the roof trusses, wall studs and floor joists to permit direct transfer of roof loads.

● Eliminate second top plate from exterior walls and interior partitions and tie two wall systems together with metal connectors.

● May not be applicable to houses with complicated floor plans or geometry.

3. OVE Framing


Advantages (to the homeowner)● None.


3. OVE Framing

Cost Savings● Typical new house: $100, assuming that 2.39 m (94 1/8”) studs are available with the extra length costing the same per unit length as the studs.

● Material savings, per floor (imperial units)

= [(0.94) x (stud cost per foot) + 0.14] x (wall perimeter, feet)

Material savings, per floor (metric units) = [(0.29) x (stud cost per metre) + 1.33] x (wall perimeter, metres)


3. OVE Framing

Background● When dimensioned lumber is used for the floor, off-centre joist splices can be used to maximize the use of even-length members & eliminate overlaps.

● Alternatively, if joist lengths on each side of the beam have the same length, the beam can be offset slightly so the butt joints are located over the beam.

4. Optimum Joist LengthAnd Beam Location

OVE/ID Alternative● Applicable to house which use dimensioned lumber floor systems.

● Use splices in the floor joists to reduce wastage.

● Alternatively, use floor joists of the same length on each side of the beam and offset the beam so the joist butt joints can be positioned over the beam.




● Energy saving: none.


Cost Savings● Typical new house: $50, assuming an average of 0.6 m (2’) of joist length can be saved for each joist spanning from wall to wall.

● Material savings, per floor (imperial units) = [(floor area, ft2) / (28) + 2] x (joist cost per foot)

Material savings, per floor (metric units) = [[(floor area, m2) / (8.54) + 2] x (joist cost per metre)

● Labour savings = 0


Background● 38 x38 (2x2) cross-bridging is used on many dimensioned floor systems In many instances, the cross-bridging can be eliminated if furring strips (19x19, 1x4) are nailed to the undersides of the joists.

● Alternatively, a panel-type ceiling can be used underneath the joists.

5. Elimination Of Floor Cross-Bridging

OVE/ID Alternative● Applicable to houses dimensioned lumber floor systems.





Cost Savings● Typical new house: $110.

● Material savings, per floor (imperial units) = [(floor area, ft2) / (5.1)] x (cross-bridging cost per foot)

Material savings, per floor (metric units) = [(floor area, m2) / (1.6)] x (cross-bridging cost per metre)



Background● Partition walls which are not load-bearing and run parallel to the floor joists do not require a double floor joist underneath them.

● The National Building Code of Canada permits wood blocking to be used (typically 38x89 (2x4) members) spaced 1.2 m (4’) underneath the partition wall.

6. Support Of Non-Load BearingPartition Walls

OVE/ID Alternative● Use wood blocking, such as 38x89 (2x4) members at 1.2 m (4’) o/c, under non-load bearing partition walls instead of doubled floor joists.


Cost Savings● Typical new house: $240, with the greatest savings occurring with larger houses.

● Material savings, per floor (imperial units) = (0.8) x (wall perimeter, ft) x (joist cost per foot)

Material savings, per floor (metric units) =(0.8) x (wall perimeter, m) x (joist cost per metre)



Background● Three-stud corners are the norm in wood wood frame construction with two studs structurally supporting the ends of the walls and the third providing backing for one edge of the drywall.

● Structurally, the third stud can be eliminated and replaced with drywall clips.

7. Drywall Corner Clips

OVE/ID Alternative● Eliminate third stud at corners and use three drywall clips to support the end of the intersecting sheet of drywall.

● Only applies to inside corners. Can also be used for other applications such as intersecting partition walls and to minimize problems with truss uplift.

● Also, very useful for retrofit applications.


Advantages (to the builder)● Reduced wood usage.

Advantages (to the homeowner)● Reduced thermal bridging meaning fewer building envelope problems.



Cost Savings● Typical new house: $16

● Material savings, per floor = ($3) x (number of inside corners)



Background● Non-load bearing partition walls are typically constructed of 38x89 (2x4) members spaced at 400 mm (16”). This is structurally excessive.

● With the exception of plumbing walls (normally built with 38x140’s, 2x6’s) and walls which contain heating ducts, there is no reason for thicker walls.

8. Non-Load Bearing Partition Walls

OVE/ID Alternative● Use 38x64 (2x3) studs at 600 mm (24”) o/c instead of 38x89 (2x4) studs for non-load bearing partition walls.

● May be perceived as flimsy construction by some consumers.

● May require reduced jamb width for doors in partition walls.



Advantages (to the homeowner)● Slight increase in useable floor area.




● Material savings, per floor (imperial units) = (2) x (wall perimeter, ft) x (2x4 stud cost per foot)

Material savings, per floor (metric units) =(2) x (wall perimeter, m) x (38x89 stud cost per metre)



Background● The locations of windows and doors are usually dictated by aesthetic concerns with little thought about the impact on framing.

● By making slight lateral adjustments to the locations of windows & doors (on at least one side) to align with the existing stud spacing, the framing can often be simplified and unnecessary studs and cripples eliminated.

9. Coordinated Framing For WindowAnd Doors

OVE/ID Alternative● Modify the positions of windows and doors slightly so that existing studs form one side of the rough-openings.

● This practice complies with the structural requirements in the NBC.


4 members 5 members Why not9 members?


Advantages (to the homeowner)● Reduced thermal bridging.

● Energy saving: average of 130 kWhe/yr (worth $7 to $14 per year)..



● Material savings = [(2 x number of windows) + (number of doors)] x (wall stud cost)



OVE/ID Alternative● Eliminate all lintels in non-load bearing walls.

10. Elimination Of Lintels InNon-Load Bearing Walls


Advantages (to the homeowner)● Reduced thermal bridging.

● Energy saving: average of 125 kWhe/yr (worth $6 to $12 per year)..



● Material savings (imperial units) = 1.4 x ( number of doors & windows) x (lintel cost per lineal foot) Material savings (metric units), = 0.4 x ( number of doors & windows) x (lintel cost per lineal metre)



Background● Plumbing walls are normally constructed with 38x140 (2x6) framing to provide space for plumbing vents and water lines.

● If the house uses a floor plan in which the bathrooms, kitchen and laundry rooms are dispersed, then more than one plumbing wall may be required.

11. Simplified Plumbing SystemStack Venting

OVE/ID Alternative● Cluster the wet rooms (bathrooms, kitchen and laundry room) around one plumbing wall.


Non-clustered Clustered


Advantages (to the homeowner)● Reduced air leakage (plumbing walls tend to be extremely leaky).

● Slight increase in useable floor space

● Energy saving: none..



● Total savings (materials and labour), = 50 x ( number of plumbing walls eliminated)


Air leakage occurring through aplumbing wall into the attic

Background● Heating grilles and registers are normally located under windows to help keep them free of condensation - which requires additional ductwork to reach the perimeter.

● However, this practice began when windows were single-or-double glazed. Today’s windows are much more resistant to condensation.

● Also, today’s building envelopes are much better insulated and more airtight than their predecessors.

12. Core Distribution For Forced AirHeating Systems

OVE/ID Alternative● Cluster the heating system grilles and registers around the central core of the house, close to the furnace.

● Use high sidewall supplies, running through partition walls, if necessary.


High Sidewall Supply

Conventional PerimeterDistribution System

Advantages (to the builder)● Reduced labour and material costs.● Simplifies the house design since some of the usual conflict between the heating/plumbing systems and the structural design of the house is eliminated.

Advantages (to the homeowner)● Fewer problems with furniture placement, especially if high sidewall supplies are used.

● Energy saving: (probably) none..



● Total savings (materials and labour), (imperial units), = 25 x (floor area* / 125)

Total savings (materials and labour), (metric units), = 25 x (floor area* / 12)

* = exclusive of basement area


Background● Windows are usually the single most expensive component of the the building envelope.

● The optimum window for a house can be defined as one which gives the best compromise between cost and energy performance while still achieving the desired durability.

● Numerous technologies (low-E films, gas fills, insulated spacers, etc.) are commonly available which improve energy performance but increase costs – sometimes significantly.

● Their performance depends on the house and its location.

● But, these treatments have wildly different costs. Which is the best window for a given house in a given location?

13. Optimized Window Selection

OVE/ID Alternative● Analyze the performance of various window options using for the proposed house using HOT2000 (or equivalent) and select the most cost- effective solution.


Advantages (to the builder)● Reduced costs.

Advantages (to the homeowner)● Improved comfort.

● Energy saving: potentially significant – up to 1000 kWhe/yr.


Cost Savings● Typical new house: potentially up to $1500, although this will vary greatly. Savings are dependent upon the house and its location.


Window Costs*:$13,300$ 4,100$ 4,200

$ 5,200

• All costs quoted by the same manufacturer

Applying OVE/ID To A Typical New House

Assume a two-storey house with wall perimeters of 40.2 m and 32.3 m and a wall area of 167 m2. If the studs cost $3.28 each and insulation costs $7.10/m2, estimate the savings.

Material savings, per floor = (0.82) x (wall perimeter, m) x (stud cost) - [(0.031) x (wall area) x (cost / m2)]

= (0.82) x (40.2 + 32.3) x (3.28) – [(0.031) x 167 x 7.10] = $158.24

Labour savings = 1.2 x (material savings)

= 1.2 x $158.24 = $189.89

Total savings = $158.24 + $189.89 = $348.13

Example Of Measure #1Exterior Wall Framing at 600 mm (24”) o/c

Assume a two-storey house with a floor area of 141 m2. If the floor joists cost $3.15 per metre, estimate the savings.

Material savings, per floor = (0.82) x (floor area, m2) x (joist cost per metre)

= (0.82) x (141) x (3.15) = $364.20


= 0.47 x $364.20 = $171.17

Total savings = $364.20 + $171.17 = $535.37

Example Of Measure #2Floor Framing at 600 mm (24”) o/c

Assume a two-storey house with a floor area of 141 m2. If the cross-bridging costs $0.44 per metre, estimate the savings.

Material savings = [(floor area, m2) / (1.6)] x (cross-bracing cost per metre)

= [(141 / 1.6)] x (0.44) = $39.90


= 1.9 x $39.90 = $75.81

Total savings = $39.90 + $75.81 = $115.71

Example Of Measure #5Elimination Of Floor System Cross-Bridging

Assume a house with 20 windows and 4 doors. If the cost per metre of the 38x184 (2x8) material used for the lintels is $2.03, estimate the savings.

Material savings, per floor = (0.4) x [(no. of windows) + (no. of doors)] x (lintel cost per lineal metre)

= (0.4) x (20 + 4) x (2.03 x 2) = $38.98

Note: since the lintel is composed of 2-38x184 (2x8) members, the cost per lintel is equal to (2.03 x 2).


= 0.7 x $38.98 = $27.28

Total savings = $38.98 + $27.28 = $66.26

Example Of Measure #12Elimination Of Lintels In Non-Load Bearing

Walls

Assume a two-storey house with perimeter air distribution system and a floor area of 141 m2. Estimate the savings of a core air distribution system.

Total savings = 25 x (floor area, m2 / 12)

= 25 x (141 / 12) = $293.75

Example Of Measure #14Core Distribution For Forced Air Heating

Systems

SUMMARY – WHAT HAVE WE LEARNED?

Optimum Value Engineering and Integrated Design are simply applied common sense (this ain’t rocket science). They have been successfully used in thousands of buildings over several decades.

Disadvantages● They require re-thinking of conventional construction practices.● OVE/ID introduces changes to the construction process (“change” = $).● Consumers may have a negative reaction – “less material means cheaper construction?”

Advantages● OVE/ID saves the builder money.● OVE/ID saves the homeowner energy and money.● OVE/ID saves resources.

optimum value engineering & integrated design

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