10 Chptr - 195 10 Roof Systems Key Terms Built-up roof Cant...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
195 10 Roof Systems Key Terms Built-up roof Cant strip Crickets Curb Flashing Hydrostatic head Low-sloped roof Multiple-layer roof Parapet Pitched roof Reglet Roof jack Shake Shingle Single-layer roof Vapor diffusion Key Concepts The expectations for roof systems and coverings are different from those of cladding systems because of the roof system's alignment to the elements. More than half of the lawsuits filed against contractors involve problems with the roof. Most energy, particularly in one-story buildings is lost through the roof. Low-pitch roofs are susceptible to ponding, which can result in a catastrophic roof failure. Objectives Summarize the critical weaknesses of roof coverings. Identify effective design remedies for roof maladies. Identify cost contributors in roof design. 196
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Purpose of Roof Systems Roofs epitomize humankind's concept of shelter, as evidenced by the expression "a roof over my head" used to describe a complete shelter. In warm climates, roofs may be the only shelter required. Roof systems constitute the sloping or horizontal plane that protects people gathered underneath it or, in a building, its interior spaces and occupants from intrusion by water, wind, sunlight, heat and cold, and sound. Roof systems include the water conveyance systems that are critical to its proper functions. The roof structure provides the required support of the roof covering and other "residents" of the rooftop such as antennae, flagpoles, mechanical equipment, equipment screens, maintenance walkways, roof hatches, crickets, diverters and jacks, and exhaust ports, to name a few, as well as the necessary geometry to divert water to collection points. The roof covering, or membrane, performs the task of protecting the roof structure, and the drainage system conducts water to the appropriate facilities located downstream. Roof systems can be divided into two principal groups: pitched roofs and low-sloped roofs (also known generically, although inaccurately, as "flat" roofs—roofs with slopes less than 3:12). From a system standpoint, roofs can be classified as single-layer, multiple-layer, and composite systems that share characteristics of both. The ubiquitous built-up roof, wood or concrete shingles, and the composition shingle roof, respectively, are examples of the three system types. The decision to use a steep or low-sloped roof often precedes the selection of the functional type, although it is certainly possible, perhaps necessary in certain circumstances, to select a material first and design the roof system around it. Each system has its advantages and disadvantages and appropriate application. Low-sloped roofs offer the designer an economical way to cover a very large building, but they are less forgiving of carelessly performed work and complex geometry. Hydrostatic pressure exerted by water that gathers in puddles is sufficient to force the water through very small openings in the membrane. That ponding can occur means that these roofs are also
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 11

10 Chptr - 195 10 Roof Systems Key Terms Built-up roof Cant...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online