Chapter 6 Flashcards
What are the 2 common types of roofing configurations?
Flat Roofs - most common used in commercial; min. recommended slope is 1/4 inch
Sloping Roofs - primarily used in residential
Common roofing construction types
1) Built-up membrane roofing - commonly used on flat roof installations; 3 basic components are felts, bitumen, and protective caps
2) Fluid applied membrane roofing - can be installed with either hot or cold materials and can be used on flat, pitched, or domed roofs; requires stable substrate; makes it easy to spot leaks; often used where free form roofs are constructed
3) Single Ply membrane roofing - PVC, EPDM, and TPO; provide membrane with significantly fewer seams; are elastic, flexible, easy to install, long lived, and resistant to ozone and ultraviolet rays; easy to repair
4) Metal sheet and metal panel roofs - designed protection from the elements, allow for positive drainage, and keep contents dry. Long life expectancy; preferred for commercial and industrial facilities
5) Shingles, Shakes, and Tile roofs - Water shedding materials, not water waterproofing; used on pitched or domed roof systems and rely on the pitch to drain wate; slopes of 3 to 4 inches per foot recommended
Roofing project concerns
1) Completion schedule and weather conditions may limit choice of roofing system, materials, and installation methods
2) Coordinating roofing with workers from other trades and keeping them off of completed roof
3) Maintainability and ease of reroofing
Roofing system selection considerations
1) Roofing design - watershed vs. waterproof
2) Building location - climate conditions and environmental factors
3) Building Use - occupants
4) Building aesthetics - color and texture
5) Owner’s preferences
Types of roofing reinforcements
1) Dry felt - organic fibers, glass fibers, or synthetics
2) Ply sheets - dry felt coated with saturant to make it water repellent; thin, flexible, conformable
3) Base sheets - coating applied to ply sheets thicker, more moisture resistant and tougher. Commonly used on concrete, wood and other nailable substrates
4) Cap sheets - surface sheet for most built up roofing systems. can be made of organic asphalt products
5) Venting base sheets - intended to be installed with mineral granules facing down
6) Flashing felts - sometimes reinforced with woven fabric for better tear resistance
What qualities are found in modified bituminous roofing systems?
They address the need to use less petroleum and they enhance the physical properties of the reinforcements an are already waterproof when they leave the factory. c
1) Elastomers - return rapidly to their initial size and shape. Typically used in rubber roofing
2) Thermoplastics- repeatedly soften when heated and harden when cooled. Typically used in plastic roofing.
Single Ply roofing systems’ benefits and drawbacks
Benefits -Top of the line in prefabricated systems. Extremely flexible and have excellent low temperature properties.
Drawbacks - BC they are single layer, redundancy for waterproofing is not possible. Workmanship at narrow seams must be perfect. Can be less resistant to abuse bc they are thin.
What common roofing details are regularly included in roofing systems?
1) Flashing - essential to completing waterproofing applications. It provides a means for terminating or interrupting the roofing membrane.
2) Coping metal - a cover for the walls extending above the roof; serves as a mini roof keeping water out of the building parapet wall
3) Roofing edges - provides a termination of the roofing at perimeter walls that do not extend through the roof; prevents moisture penetration
4) Isolating Roofing Components - Isolating them will minimize chances of the forces of expansion causing the break in the waterproof membrane
5) Roof mounted equipment - If possible, place mechanical equipment somewhere other than the roof; avoid pitch pockets bc they require refilling to stay water tight; use premolded boots instead
Value of roofing maintenance programs
To protect the investment in the building and its contents; it will add years to the life of the roofing and can also detect problems before damage occurs.
