How To Figure Gambrel Roof Angles

Move slider or directly enter angle to alter sweep angle of lower rafters and change the shape.

How to figure gambrel roof angles.

With overhang selected drag slider to increment decrement birdsmouth seat width to suit. Since the sum of the three angles in a gambrel roof is 180 degrees the angles you will need are as follows. Use the protractor to measure those angles at the peak the walls and the point where the two lines intersect on the top side of the roof. You will need to make 22 5 degree angle cuts on the rafter joist ends that mate up to the top plate or header.

Draw a semi circle on the graph paper mark a center peak at the top and draw two lines on each side in the shape desired for the gambrel roof. With overhang selected drag slider to increment decrement birdsmouth seat width to suit. The preview drawing displays a dimensioned elevation view of the gambrel roof. Check overhang to calculate rafter overhang equal to the lower level cut at the full rafter depth.

Don t forget to include any overhang and make sure you input measurements as a single number 2 25 instead of 2 3. Span 2 73 will get you equal parts at these angles. For overhang you ll have to use a 30 60 90 to figure out the added width. Gambrel roof framing geometry calculator inch this gambrel roof fits in a semicircle and starts as the top half of an equal sided octagon.

Check overhang to calculate rafter overhang equal to the lower level cut at the full rafter depth. Gambrel roof framing geometry calculator metric this gambrel roof confines to a semicircle and starts as the top half of an equal sided octagon. To calculate a gambrel roof select gambrel roof from the roof type dropdown list or click on the appropriate toolbar button to calculate a gambrel roof. 45 degrees where the joists meet up with the top plate or header and 90 where the joists meet in the middle at the ridge board.