More Picture Of How To Determine Roof Truss Size Free Download. For example 412 pitch means 4 inches of rise in 12 inches of run. C rafter length.
Equationa2 b2 c2. Pull a tape measure along the top plate of the house to determine the length of the roof while the assistant holds the other end. This is based upon the span of the rafter horizontal span not total rafter length live and dead loads.
Joist sizes was by taking an old-fashioned measurement a pencil and a piece of paper and then adding a whole lot of brain power.
Pull a tape measure along the top plate of the house to determine the length of the roof while the assistant holds the other end. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. For example 412 pitch means 4 inches of rise in 12 inches of run. Measure out 5 to 6 trusses at a time.