enclosing super framed structures
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ENCLOSING FRAMEDSUPERSTRUCTURES
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WHY THE FRAMEWORK IS ENCOSED
Our starting point in a building framework of
wood, steel or concrete. The framework is by itselfis of very little value. It needs to be enclosed with
an exterior skin that will keep out sun, rain, snow,
wind, heat, cold, and air pollutants such as dust
and smoke.
ENCLOSING FRAMED SUPERSTRUCTURES
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WHY THE FRAMEWORK IS ENCOSED
Building such as house, school, or an office
building requires some additional features to make
them useful and attractive. The features which
enclose the inside of the building are floors, ceilings,
partitions, and the insides of exteriors walls. This
features permit control of the temperature,
humidity, light, and noise inside the building. It alsoimprove the appearance by hiding utility lines and
by providing attractive textures, colors, and
decorative details.
ENCLOSING FRAMED SUPERSTRUCTURES
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WHO ENCLOSES THE FRAMEWORK?
The architect usually selects the methods and
materials for enclosing the framework of a building.He makes selections based on appearance,
economy, and the purpose for which the rooms will
be used, and upon the recommendations of a
structural engineer who may design the frame in a
large building.
ENCLOSING FRAMED SUPERSTRUCTURES
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WHO ENCLOSES THE FRAMEWORK?
The general contractor is responsible for
enclosing the building although he may
subcontract parts of the job such as roofing ,tilework, and painting to specialty sub-contractors.
Many different types of craftsmen are
employed. There are carpenters, masons roofer,sheet metal workers, glaziers (who install glass),
laborers, painters, tile setters, cement finishers,
paperhangers, and ironworkers.
ENCLOSING FRAMED SUPERSTRUCTURES
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ROOFING
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As a top cover of a building, the roof protects
the inside from damage by wind, rain, and snow. A
roof may also add to the appearance or character ofa building.
ROOFING
A roof is a watertight skin which coversthe top of a building. The roof is usually put on
before exterior walls are started and before
floors are laid.
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TYPES OF ROOF
FLAT ROOF
A flat roof is seldom really level. Usually it
has a very slight lope or slant. It is used mostly in
commercial or industrial construction.
ROOFING
Flat roofs are those slope is less than 1 in 4
and use waterproof membranes (also called Low
Slope)
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PITCHED ROOF
A pitched roof has a much greater slant or slope
than a flat roof. It is most often used for houses, but itmay be applied to other structures to achieve a
pleasing architectural effect. Also, some buildings have
a straight or curved sloping roof. An example might be
a church or a large auditorium.
ROOFING
TYPES OF ROOF
Pitched roofs have slopes of 1 in 4 or greater and
generally use shingles
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Pitched Roof: Clay Tiles
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Metal Roofing
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ADVANTAGE OF FLAT ROOFS
The biggest advantage of a flat roof is that the
space directly underneath is completely usable.
A flat roof offers several cost advantages. It has the
least amount of floor space covered. It uses the
cheapest materials. The roofing operation can be
done by the most modern mechanized equipment.
ROOFING
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ADVANTAGE OF FLAT ROOFS
Sometimes a flat roof requires a heavier
framework than does a pitch roof. However, thecost advantages of a flat roof nearly always
outweigh this disadvantage. Accordingly, flat roofs
are most common for large buildings unless a
specific architectural effect is desired for the sakeof appearance or utility.
ROOFING
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SUPPORTING FRAMEWORK
A roof is supported by the framework of a
building. The part of the framework that lies directly
under the roof is a system of concrete, steel, orwooden rafters, beams, trusses, or reinforced
concrete slab.
ROOFING
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DECK
On top of the supporting framework, the roof deck
is laid. The deck supports many things:
1. Weight of the roof,2. The snow or rain,
3. Roof-top equipment such as air conditioning
units, and
4. Equipment used by the roofer.
ROOFING
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DECK
The deck may be made of steel, prestressed
concrete, plywood, gypsum, vermiculite, shredded
wood fibers, or fiberboard. Roofs usually cover
large areas and are subjected to wide variations in
temperature, Therefore, roof decks are
constructed with expansion joints. The decking islaid by a roof-deck contractor or by a general
contractor.
ROOFING
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INSULATION
The outside of the building consists of the
exterior walls and the roof. On a modern one-story
factory, the roof area may be as much as 95% of the
total surface. It is important that the roof be
properly insulated to prevent the loss of heat in the
winter and cooled air in the summer.
ROOFING
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BUILT-UP ROOFING MATERIALS
90% of all flat roofs are of the built-up type. Three
kinds of materials re combined in a built-up roof:
roofing felt, bitumen (asphalt or tar), and gravel (orslag)
Roofing felt is a mat of fiber which has been
soaked (at the factory) in bitumen. It comes in rolls
36 wide and in a number of weights
ROOFING
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BUILT-UP ROOFING MATERIALS
The bitumen is a thin liquid when heated,
and it is easy to apply. However, when it cools, it
becomes a soft and flexible solid. It seals againstthe passage of water.
ROOFING
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BUILT-UP ROOFING MATERIALS
The gravel or sag consists of pieces about he size of a
pea. It has many uses:To protect the roof against foot traffic
To help the roof resist uplift (Blowing of the wind)
To protect the bitumen from the direct rays of the
sun, andTo reflect and absorb the heat of the sun, thus
keeping the roof cooler.
ROOFING
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LAYING A BUILT-UP ROOF
In laying a built-up roof, the bitumen is
heated and spread, or mopped on top of the
insulation. A roll of felt is laid in the hot bitumen,
and more bitumen is mopped over three-fourths
of its width. On top of the bitumen, another strip
of felt is laid so that it laps over three-fourths of
the with of the previous strip of felt.
On top of the last layer of felt is spread a heavier layer of bitumen called
flood coat. The gravel or slag is spread evenly and embedded in the flood
coat while it is still hot. A smooth surface on a roof is simply finished with
a flood coat. No gravel or slag is used.
ROOFING
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LAYING A BUILT-UP ROOF
On top of the last layer of felt is spread a
heavier layer of bitumen called flood coat. The
gravel or slag is spread evenly and embedded in
the flood coat while it is still hot. A smooth
surface on a roof is simply finished with a flood
coat. No gravel or slag is used.
ROOFING
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FLASHINGS
Flashing are strips of materials which seal
the joint between roofing and anything else that
projects or rises above it. Flashing are needed atthe edges of built-up roofing, around pipes, vents,
and chimneys, and at expansion joints.
ROOFING
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A significant environmental improvement to roofingapplications has been the invention or adoption of
green roof practices.
Green roofs are installed over a modified version of more
conventional flat roofs, and are normally comprised of a
system that is sold by several green roof manufacturers
(like Soprema)
These roofs have been used widely in Europe for many years
Two main types:
intensive(thicker growth medium required for larger plants)
extensive(thinner, lighter growth medium required for smaller
plants) - this one is more popular
GREEN ROOFS
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Mountain Equipment Coop, Toronto:
This environmentally conscious retailer has chosen to usegreen building practices on their buildings.
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Vancouver Public Library:
The green roof on VPL is not accessible to the public (has no guard
rails at the edge) and is planted with grasses. The idea being to
reduce urban heat island while providing a nice view for taller
buildings adjacent
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YMCA Environmental Learning Centre:
This building illustrates the ability to install a green roof ina sloped situation
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Fairmont Hotel, Vancouver:
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Green Roof Benefits:
Planting reduces urban heat island effects
planting can be used to absorb rain water
and decrease water that must be processedby the urban storm sewer system
visually pleasing
additional insulation
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Green Roof Drawbacks:
Why not do a green roof?
Additional first expense
additional structure required to support
roof
plants must be hardy and not needwatering (over the long term)
watering essential during the first 2 or soyears until roots become established
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Roof and membrane failures are the most
often litigated parts of a building
good detailing is paramount
never use materials or systems that have
not been approved or tested by areputable agency