50 psf of snow is Massachusetts. Not here.

S = C_b·Ss + Sr, with YOUR town's Ss and Sr.

Nearly every timber-framing book in circulation is American. Beemer's example frame is designed for 50 psf of snow — 2.39 kPa. That is western Massachusetts. Cape Cod is 25 psf; the Rockies, over 200.

In Quebec the load is calculated: S = C_b·Ss + Sr, using your town's Ss and Sr from appendix C of the 2020 NBC. C_b is 0.55 — or 0.45 if your roof is 4.3 m wide or less, which covers many small buildings. Taking 2.0 kPa as a default underestimates by 30 to 48 % as soon as you leave Montreal.

What it hits first: rafters and plates. No rafter, plate or tie-beam section from an American book carries over unchanged. The calculation has to be redone.

The generator asks WHERE you are building: it reads your town's Ss and Sr from the code, applies the C_b for your roof, and sizes with that. If your town is not listed, you enter your own snow load.

Source : calcul-des-structures-partie4.md · beemer §3