Roof Truss Minimum Pitch

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.

Roof truss minimum pitch.

Depending on your roof slope add 4 to 5 inches for heel height. For example if you use a heavy load of asphalt shingles a minimum pitch of 2 12 is needed for proper drainage. To get the minimum pitch for a metal roof the vertical rise per foot is divided by the horizontal slope. The best outcome of the pitch depends on the covering of the roof.

Calculate the height of a common truss using the building width and the slope of the roof. The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. 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.

Note that roof pitch is sometimes used in parallel with roof slope. I e 4 inches of rise per 12 inches one foot of run. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. Pitches should in most cases never exceed 12 12 or else the roof is dangerous to walk on.