How to Build a Gambrel Roof

Two Methods:Layout and Construction of TrussesRaising the Roof

Roofs come in a variety of styles and shapes. A gambrel roof is often associated with barns. The advantage of this style is that it offers increased storage space under its steeper sides. Many people also find use for it in their homes. It is really no more difficult to build a gambrel roof than a standard peak roof.

Method 1
Layout and Construction of Trusses

  1. 1
    Lay out the 2 x 6-inch (5 x 15 cm) truss materials on a level area, overlapping the joints.
    • Mark the angles to make the peak (ridge). Dogleg that from the sidewalls, the bottom angle where the truss sits on the loft or 2nd floor joist. Another rafter will fit between the doglegs to provide extra support.
      Image titled Build a Gambrel Roof Step 1Bullet1
    • The peak of the gambrel roof normally is 30 degrees with the doglegs 60 degrees. However, they can be whatever fits your purpose.
      Image titled Build a Gambrel Roof Step 1Bullet2
    • Use these pieces as a pattern to mark and cut the rest of the gambrel roof trusses. Cut enough pieces for trusses to be installed on 16-inch centers. Use .5-inch (12 mm) plywood to make brackets for securing the pieces together. Cardboard pieces drawn and cut to size make excellent patterns for the straps.
      Image titled Build a Gambrel Roof Step 1Bullet3
  2. Image titled Build a Gambrel Roof Step 2
    Assemble the roof trusses using the .5-inch (12 mm) plywood that you cut for straps.
    • Nail the straps at the joints on both sides of the trusses with 6 penny nails.

Method 2
Raising the Roof

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    Install the trusses, nailing with 16 penny nails, starting from either end of the building.
    • You will begin nailing to the floor or ceiling joist. Plumb and square up the trusses as you install using scrap 2 x 4-inch wood (5 x 10 cm). Keep checking that they remain plumb.
  2. Image titled Build a Gambrel Roof Step 4
    Begin installation of the roof deck once you have enough trusses in place. Lay a minimum of .75-inch (19 mm) plywood lengthwise from the bottom up to the center ridge using 12 penny nails. Again, keep verifying as you go that the trusses are plumb.
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    Frame in the end once the trusses and deck have been installed. The gambrel roof for exterior walls uses 2 x 4's (5 x 10's) on 16-inch (40 cm) centers. Add any additional framing needed for doors or windows.
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    Mount the siding and doors or windows of your choice on the end walls.
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    Cover with a waterproof membrane, such as asphaltic roofing paper, and the shingles or roofing material that you want to use.


  • You need to increase the thickness of roofing decks from the minimal .75-inch (19 mm) plywood if you live in areas that get heavy snow loads.


  • Offset the joints of the plywood decking so they are not all aligned on the same rafter for added structural integrity.
  • Always follow good safety practices and manufacturers' recommendations when using power tools or ladders.

Things You'll Need

  • 2 x6-inch wood (5 x 15 cm)
  • 2 x 4-inch wood (5 x 10 cm)
  • .5-inch (13 mm) exterior plywood
  • .75-inch (19 mm) exterior plywood
  • 6 penny nails
  • 16 penny nails
  • 12 penny nails
  • Framing hammers
  • Circular saw
  • Carpenter's square
  • Tape measure
  • Chalk or pencil
  • 4-foot (3.3 m) level
  • Siding of your choice
  • Waterproof membrane
  • Roofing material of your choice.

Article Info

Categories: Build Design & Remodel Own Home | Exterior Walls and Roof