Roof Truss Minimum Pitch

Calculate the height of a common truss using the building width and the slope of the roof.

Roof truss minimum pitch.

I e 4 inches of rise per 12 inches one foot of run. If you can t get the heel height most residential trusses will have a 3 top cord. Most metal roofs will have minimum pitches of three in twelve but this might sometimes go down depending on whether there are special installation procedures issued by the manufacturer regarding that particular roofing material. To get the minimum pitch for a metal roof the vertical rise per foot is divided by the horizontal slope.

If a roof slope rises say 4 inches when measured 12 inches along the bottom of a horizontal roof truss the roof slope is said to be 4 12. Rafter length from rise. Pitches should in most cases never exceed 12 12 or else the roof is dangerous to walk on. The best outcome of the pitch depends on the covering of the roof.

However roof pitch is technically measured and defined differently and will not be discussed here. Note that roof pitch is sometimes used in parallel with roof slope. For example if you use a heavy load of asphalt shingles a minimum pitch of 2 12 is needed for proper drainage. Wilson roof truss ltd.