Carpentry & Building Construction

Chapter 19: Roof Assembly & Sheathing

Chapter Summaries

Section 19.1 Ridges
Ridges can be structural or nonstructural. Calculating the length of a ridge requires actual measurements taken from the framed building. The ridges for dormers and additions can be calculated with the assistance of a sketch of the roof plan.

Section 19.2 Roof Assembly
A careful rafter layout is important so that rafters will bear properly on the ridge board or ridge beam. Common rafters are generally installed first, then hip and valley rafters. Jack and hip jack rafters are installed last.

Section 19.3 Special Framing Details
Special framing details include collar ties, purlins and braces, gable ends, roof openings, shed dormers, and chimney saddles.

Section 19.4 Rakes & Cornices
Cornices can be constructed in various ways, based on the architectural style of the house and the climate. The three types of cornices are open, box, and closed. A rake is the part of a gable roof that extends beyond the end walls. Careful detailing is required at the rake, particularly at the cornice returns. The joints must be tight to prevent water from getting through.

Section 19.5 Roof Sheathing
Roofs may be sheathed with panels or lumber. Panel sheathing adds considerable strength to the roof system.