Gambrel Roof Angles Formula

You want to try and use angles that are as close to 45 as you can get for both ease of construction and good strength.

Gambrel roof angles formula.

The lower slope length is measured from outside wall to the start of the upper sloped roof section. Move slider or directly enter angle to alter sweep angle of lower rafters and change the shape. Besides its unique appearance a gambrel roof also serves to maximize the usable floor space in the attic area. Determine a pitch for the top slope of the gambrel roof the rise in inches per foot from the midpoint connection to the peak.

With the gambrel roof design there are four angles that are used to make up a total of 180 degrees. Gambrel roof a gambrel or barn style roof is simply a gable roof with a change in slope partway up the roof. The purlin method calculates cuts that bisect the angles at the roof joints. You will need to make 22 5 degree angle cuts on the rafter joist ends that mate up to the top plate or header.

Reverse that for the bottom angle. Check overhang to calculate rafter overhang equal to the lower level cut at the full rafter depth. Make that pitch 12 7 a drop of 7 inches per foot from the connection to the wall. With overhang selected drag slider to increment decrement birdsmouth seat width to suit.

Gambrel roof square footage calculator calculate the square footage of a gambrel style roof using imperial measurements. 7 12 or a rise of 7 inches per foot is a common top gambrel pitch. Move slider or directly enter angle to alter sweep angle of lower rafters and change the shape. With overhang selected drag slider to increment decrement birdsmouth seat width to suit.

If you are thinking of a building project that involves a gambrel roof design here are a few tips to help you calculate the angles. 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. Since the sum of the three angles in a gambrel roof is 180 degrees the angles you will need are as follows. Gambrel roof framing geometry calculator metric this gambrel roof confines to a semicircle and starts as the top half of an equal sided octagon.