How to Build a Gambrel Roof

A gambrel roof is definitely one of the most fancied type of truss designs in roof building due to the adequacy in space due to more areas use and it encompasses two sloped roofs instead of one. Here are a few steps to take in building your own gambrel styled roof.

Learn more about Gambrel Truss Designs on Wikipedia:

Plan your Project – Compute the gambrel roof size, amount of roof trusses needed, measure roof height, buy either prefabricated trusses or making them yourself. Securing a level ground to build your trusses and layout, make templates and stakes, and mark for angling and cutting according to your desired gambrel roof configuration.

Trusses Assembly and Placement – angle and cut with templates, then assemble and position your gambrel roof trusses. Attach the braces with nails, and strap metal, which are then raised and secured into position. Place the roof sheathing and calculate the thickness due to snow loads.
The End Walls – finally, insulate and waterproof, cut studs of end walls, frame any windows, enclose plywood end, and finish with shingles or sidings that you wish for your gambrel roof.

Calculation of Gambrel Roof Measurements

Gambrel roof trusses are formed by a raised ridge consisting of two sides to that are joined at the center. With differing slopes, each side of horizontal sections splits into two. To increase the available upper floor space, upper portion should have a smaller pitch and a steeper pitch for the lower roof to deter rain and snow accumulation. Calculation of gambler roof measurements is listed below.

    • Determine roof length, starting with the upper portion of the gambrel roof, establish the horizontal width and vertical height.


  • Divide the upper roof’s height by its width. Using a scientific calculator calculate the angle of pith (inverse TAN, in degrees) of the upper roof.



  • Square the width and height and add them together. For the upper roof’s flat width, solve for its square root.



  • The upper roof total area is calculated by multiplying the length of the roof with its width.



  • To calculate for the lower portion of the gambrel roof, just repeat steps 1 to 4.

Additional Resources:

How to build a Gambrel Roof




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