Tempo:
roofing materials to reduce the risk of water backing up through the roof membrane. The minimum allowable slope for asphalt shingles is 1:6, and there are different installation requirements for roof slopes of 1:3 or greater and slopes less than 1:3. There are minimum allowable slopes for each type of roofing material. The dimensions of roof joists and rafters for the various grades and species of lumber and for various live loads are given in Tables 29 to 32 (p. 295-301).
PITCHED ROOFS Prefabricated roof trusses are most often used for framing residential roofs. Rafters framed on site are sometimes used. Of the pitched roofs, the gable roof is the simplest to construct. Other pitched configurations, such as a hip or L-shape roof, can also be framed with trusses (Figure 77).
Prefabricated Roof Trusses Prefabricated roof trusses offer many advantages. They are designed to handle snow loads that the trusses will be subjected to, are manufactured
77 L-shape trussed roof See isometric below
ridge valley trusses roof sheathing gable end
girder truss common trusses double wall plates
Note: For clarity, some structural members of some of the trusses have been omitted, and roof sheathing appears continuous.
PITCHED ROOFS Prefabricated roof trusses are most often used for framing residential roofs. Rafters framed on site are sometimes used. Of the pitched roofs, the gable roof is the simplest to construct. Other pitched configurations, such as a hip or L-shape roof, can also be framed with trusses (Figure 77).
Prefabricated Roof Trusses Prefabricated roof trusses offer many advantages. They are designed to handle snow loads that the trusses will be subjected to, are manufactured
77 L-shape trussed roof See isometric below
ridge valley trusses roof sheathing gable end
girder truss common trusses double wall plates
Note: For clarity, some structural members of some of the trusses have been omitted, and roof sheathing appears continuous.
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