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We would like to put a Gambrel Roof on a 32 x 32 log cabin we're building but I don't know the formula or how to build the Gambrel roof. Please help

We're building this cabin ourselves and love the gambrel roof style. How do we build the roof exactly? What angles, how do we lay it out. I have 6 x 6 rough lumber, 16 foot long.

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2 Answers 2

You can use a program to calculate the angles for your desired gambrel shape. Here is one such example:


As @Skaperen says, a basic gambrel is nothing more than 1/2 of an octagon.

Gambrel Types Easy Rafters groups gambrel roofs into two categories, regular gambrels and custom gambrels.

A regular gambrel is one that fits inside a circumscribed semi-circle as shown below (the shape of the roof is essentially one half of a regular octagon). The slopes for a regular gambrel roof are fixed at 28 31/32 over 12 for the lower rafters and 4 31/32 over 12 for the upper rafters (these slopes are rounded to 29/12 and 5/12 for display) and the length of each side or face will always be equal. Whenever the lower span dimension is changed the other dimensions are automatically recalculated to maintain the same regular proportions.

Custom gambrels on the other hand allow complete flexibilty of design without the constraints of the regular gambrel option.

Regular Gambrels

Regular Gambrel
A regular gambrel fits inside a circumscribed semi-circle.

Custom Gambrels

Custom Gambrel

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There are no specific dimensions. Use whatever you believe will be pleasing and practical. Historically it's just a roof over a partial roof where the cross bar at the top of the lower roof is the "gambrel" in a barn used to hang large tools, material, game to be skinned, etc.

If you want to be geek about it, start with an octagon and use those angles.

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