I can't see pricing a frame by the square foot of the building or board foot of timber, both being very different things. All my work is priced on the individual frame, they are all different. The base of my caculation is the joinery. Other consideration are bent spacing and how complicated the joinery decisions will be. Will you be lodging joist and purlins or using pockets? Compound joinery or not? What is the finish of the timbers expectation, planed, sanded, oil, raw with no finish at all, dirt included. Bent spacing on a building can double the price alone, with no other factors.

How do you consider all these factor when using a square foot number?