HC-Lecture30-Roofing

HC-Lecture30-Roofing - Heavy Heavy Construction...

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Unformatted text preview: Heavy Heavy Construction Construction Lecture Lecture #30 #30 Roofing L Prieto-Portar 2008 Roofing. The roof is the first line of defense against the weather, precipitation (rain, hail or snow), the sun and thermal transmission (both in and out of the dwelling). Roofs are subjected to extreme heat and cold and so its surface must withstand a wide temperature swing. Roof Groups: Steep and low-slope roofs. (A) Steep roofs. The advantages of a steep roof is that it drains quickly and thus there is less opportunity for gravity or wind to push the water through the roofing material. This is an advantage for the use of inexpensive, small roof units, such as shingles, that are easy to handle and install, they accommodate thermal expansion and contraction structural movements, they vent water vapor easily and are visibly aesthetical. (B) Low slope roofs. Low-slope roofs have the advantage that they can inexpensively cover a large horizontal surfaces compared to steep roofs. Because low slope roofs typically have simpler geometries, they are often less expensive, and can serve in other functions, such as patios, decks, parking for automobiles, etc. Their main disadvantage is that water drains slowly, and thus increases the opportunity for leaking into the structure; any slight structural movement may tear the roof membrane; a minor intrusion of moisture (for example, during construction) can lead to water vapor blisters that will rupture the membrane, etc. The components of a low-slope roof from the bottom up are, 1) start with the structural support, the roof deck; 2) place the thermal insulation; 3) cover with the vapor retarder; 4) lay the roof membrane; 5) spread the roof ballast (as a protection); 6) add drainage components (scuppers, gutters, etc.) and 7) add flashing components. 1) The roof deck. The deck materials of the roof range from plywood, steel sheeting to concrete slabs. The performance requirements of the flat roof are,- to support the loads upon the roof,- to resist wind uplift forces,- sloped for positive drainage, - to support any expansion and contraction of the roofs structure,- provide a smooth and clean surface, and be- thoroughly dry prior to the membrane placement. 2) The thermal insulation....
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This note was uploaded on 09/15/2011 for the course CCE 4001 taught by Professor Staff during the Spring '08 term at FIU.

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HC-Lecture30-Roofing - Heavy Heavy Construction...

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