As in the picture- hold the RoofGuessEstimator level and slide the free end till you match the angle of the roof. The corresponding number in the sight window (on the free end) tells the pitch of the roof.
To determineroof area:
Simply (Multiply) the measured Length +overhangs by the Width+overhangs of the house (the foot print of the house) =xxxx area
Then Multiply this foot print area (xxx) by the corresponding Pitch Factor = ROOF AREA