First time posting, but have enjoyed this site for many years.

Wanting to build a retirement A-Frame, using 6' block side-walls on a slab. Approximate dimensions 24' wide and 40' deep. Can't seem to find a site with rafter calculations that don't confuse me totally! Can I span this with 2x12x24 Hem-Fir? Yellow Pine is twice the price.

Equilateral triangle from the tops of the side walls, so the rafters will be roughly 24' long on each side. Height from slab to peak calculates to just over 29'. Loft bedroom on the rear half of the 40 depth, so second-floor joists will form the base of the triangle there, at about 9' from the slab floor. Collar-ties at an appropriate height across the front half of the house, under a vaulted ceiling.

Any help with figuring out the rafter sizing and type of wood necessary for this structure would be much appreciated!