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Lecture13-MoistureProtection1.pdf

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CSMT 441

Waterproofing

Lecture 13

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Water protection

• Damp-proofing and Water-proofing

• Shingles and Roof Tiles

• Roofing and Siding panels

• Membrane Roofing

• Flashing and Sheet Metal

• Roof Specialties and Accessories

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Damp-proofing and Water-proofing

• Damp-proofing resists dampness, but is not

designed to resist water pressure (painting the wall

with bituminous materials)

• Waterproofing resists the passage of water and the

hydrostatic pressure to which a wall or floor might

be subjected to (membrane waterproofing)

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Membrane Water-proofing

• It consists of a buildup of tar and membranes (plies) into a strong impermeable blanket.

• Plies (woven glass fabric, saturated cotton fiber, and tarred felts) provide strength and flexibility to the membrane.

• Unit: square (100 sf) – Check the Specs. for

• number of plies (2 to 5)

• the kind and weight of ply

• type of coating (tar or asphalt)

• the pounds of coating material

• the lap required over each strip of reinforcement

• and the type and thickness of protection coating

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Materials required for one square (100 sf) of

membrane waterproofing

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Roofing

• Roofing includes roof covering, insulation,

and roofing accessories (e.g., flashing)

• Pitched roofs are sloped to drain water to

the perimeter of the building

• Flat roofs are sloped to interior drains (1/8"

to 1/4" per foot)

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Roofing

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Roofing

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Roofing

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Shingle Roofing

• It is used in sloped roof (a slope of 3" or more per foot)

• Available in asphalt, wood, fiberglass, slate, aluminum, and steel

• Asphalt shingles (AS) are 12 and 15" wide, and 36" long. The exposure generally is 4, 4.5, or 5".

• AS are specified by the weight per square, fire rating, and resistance to wind

• Unit: Square (100 sf)

BCN 5618 12

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Shingle Roofing – Cont.

• Allow one extra course of shingles at the eaves (the first course must be doubled).

• Hips and ridges are taken off by LF and considered 1' wide.

• Waste ranges between 5 to 8%.

• 1.5 to 3 pounds of galvanized large-headed nails, 7/8" to 1 3/4" long are used per square.

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Underlayment

• Underlayment of building paper or roofing

felt is generally used

– unit: SF

– no. of layer and weight should be specified

– 5 to 8% waste.

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Tile Roofing

• Used on sloped roofs

• Made of clay or concrete

• Durable, attractive, but expensive

• is heavy and needs stronger supporting

system.

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Metal Roofing

• Preformed

– used on pitched roofs

– made of aluminum or steel (galvanized, painted, or coated with asphalt)

– fastened with self-tapping screws and neoprene washers to purlins.

• Formed

– used in sloped roofs with plywood and concrete base

– made from copper, tin, and lead

– flat sheet metals are joined by tool formed batten-seams.

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Flashing

• Flashing is used to keep water from getting under the roof covering and from entering the building wherever the roof surface meets a vertical wall

• It is needed in the perimeter of the roof and around penetrations through the roof.

• It is made of aluminum, copper, stainless steel, rubber, or plastic

– unit: no of pieces, LF with the width and thickness noted

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Manufactured Roof Specialties

• Gravel Stop- serves as termination of gravel at the edge of roof, as counter flashing, and as decorative strip

– unit: no of pieces, LF with the width, thickness, and material noted.

• Gutter and Downspouts (LF, material, size, thickness)

• Expansion Joints (LF, material, thickness, width)

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