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PowerPoint ® Presentation Unit 46 Basic Roof Types and Roof Theory Basic Roof Types Roof Layout Principles Structural Factors in Roof Design Roof Sheathing.

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Presentation on theme: "PowerPoint ® Presentation Unit 46 Basic Roof Types and Roof Theory Basic Roof Types Roof Layout Principles Structural Factors in Roof Design Roof Sheathing."— Presentation transcript:

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2 PowerPoint ® Presentation Unit 46 Basic Roof Types and Roof Theory Basic Roof Types Roof Layout Principles Structural Factors in Roof Design Roof Sheathing

3 Unit 46 — Basic Roof Types and Roof Theory Shed, gable, and hip roofs are the basic types of pitched roofs.

4 Unit 46 — Basic Roof Types and Roof Theory Gambrel and mansard roofs are similar to gable and hip roofs except that they have double slopes on each side.

5 Unit 46 — Basic Roof Types and Roof Theory Butterfly and monitor roofs are variations of the shed roof design. Continuous ‑ slope gable roofs are a variation of the gable roof design.

6 Unit 46 — Basic Roof Types and Roof Theory An intersecting roof is formed when two roofs are combined. Among the many possible variations are the L ‑ shaped gable and L ‑ shaped hip intersecting roofs, and the T ‑ shaped hip ‑ and ‑ gable intersecting roof.

7 Unit 46 — Basic Roof Types and Roof Theory The shape of a gable roof is based on two right triangles. A common roof rafter forms the third side (hypotenuse) of each triangle.

8 Unit 46 — Basic Roof Types and Roof Theory The unit rise of a roof is the number of inches the rafter will rise vertically for every foot of run.

9 Unit 46 — Basic Roof Types and Roof Theory The total rise of a roof is based on unit rise and total run.

10 Unit 46 — Basic Roof Types and Roof Theory Purlins and braces help support spans of longer rafters.

11 Unit 46 — Basic Roof Types and Roof Theory The allowable span is the distance from the ridge to the outside wall plates. Rafter spacing and roof slope determine the allowable span. For example, 2 × 4 rafters spaced 16″ OC have an allowable span of 8′ ‑ 0″ if the unit rise of the roof is less than 4″. The allowable span is 9′ ‑ 0″ if the unit rise is 4″ or more.

12 Unit 46 — Basic Roof Types and Roof Theory A slope cut must be made on the ends of ceiling joists.

13 Unit 46 — Basic Roof Types and Roof Theory As high-velocity wind passes over a pitched roof an uplift force is created, pulling on the roof surface.

14 Unit 46 — Basic Roof Types and Roof Theory Rafter and truss anchors tie rafters and trusses to the building walls.

15 Unit 46 — Basic Roof Types and Roof Theory Panel products such as plywood and OSB are typically used for roof sheathing. Panels are attached to roof rafters using 8d common nails or screws.

16 Unit 46 — Basic Roof Types and Roof Theory Panel clips are placed at the unsupported edges of roof sheathing panels and eliminate the need for blocking between rafters. Panel clips are made of galvanized steel and accommodate all panel thicknesses used for roof sheathing.


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