The generator

Where are you building?

Pick your town …or your own snow load S (kPa)

Snow load and seismic hazard are read town by town in appendix C of the code. A 2.0 kPa default underestimates by 30 % in Quebec City and 48 % in Gaspé — a rafter there would be a full size too small. If your town is not listed, enter your own snow load.

Building width (ft) Building length (ft) Number of bents Top of plate (ft) Top of tie beam (ft) Pitch (12:12 = 1)

Your frameRoof

Common rafters — closely spaced rafters on the plate, collar ties — Sobon's frame (Beemer)
Principal rafters and purlins — 7×10 rafters at the bents only, 6×7 purlins at 48 in — Chappell's plans

Tie beam

Below the plate — wedged half-dovetail, bent raised flat; more than 2 ft below the plate, the post bends (Beemer)
On the plate — English tying joint: the thrust stays in the triangle; jowled posts, walls raised first (Chappell)

Bent

Plain — the tie beam and its rafters
King post — beyond 24 ft, up to 36 ft; the king post is in tension, struts carry the rafters; with the purlin roof only (Chappell)
Queen posts — from a 20 ft span, up to 30 ft; with the purlin roof only (Chappell)

The generator

Where are you building?

If that was useful

The full set