Glossary · P
Pitch
Also called roof pitch, slope
The slope of a roof, given as an angle, as a ratio of rise to run (e.g. 9 in 12), or as the rise over the span. Each covering has a minimum pitch below which it will leak.
See also: Gable
Rules that use the word
Qing jǔjià: five-tenths at the eaves, nine at the ridge. Give each rafter span a fixed slope, increasing from the eaves to the ridge: half-pitch (5 jǔ) for the eave span, then about 6½ or 7, 7½, and 9 tenths for the span below the ridge.
Each covering has its lowest pitch. Pitch a roof no lower than its covering allows (roughly 45° for thatch, 35° for plain tiles, 20–25° for slate, 15–20° for interlocking tiles, a few degrees for sheet metal) and steeper where snow lies long or rain is heavy.
Name a roof by its slopes. Classify a roof by how its planes meet: one slope (shed), two meeting at a ridge (gable), four meeting at hips (hip, pyramid), a hip below a gable (hip-and-gable), two pitches each side (gambrel, mansard), or a curved surface (barrel, cone, dome).
The log frame. Build the house of whole logs laid horizontally and notched into one another at the corners, their ends left projecting; stop the joints with moss; roof it with boards or birch bark on a steep pitch; raise the living room on a lower storey where the ground is damp.
Where it appears in the book
In the chapters The Roof, Stairs, The Temple, The Modern Movement.
Nearby in the glossary
Pilaster · Pilotis · Pinnacle · Pishtaq · Plate tracery · Pleaching · Plinth · Poché