How to Design a Gambrel

Planning

• 1

  Determine the number of trusses that are needed for your roof by calculating the size of your building. You can determine this amount by using the centre of the roof and measuring the length of each side. The space between trusses must be at least 16 inches.

• 2

  Decide the height of your gambrel roof. The top of a gambrel roof will be at a 30-degree angle and the bottom will be at a 60-degree angle. The larger the structure, the higher the roof will be.

• 3

  Decide if you are going to make your own trusses or purchase them ready-made.

Layout

• 4

  Purchase 2-by-6 lumber to make the trusses; available at most lumberyards.

• 5

  Lay out the wood on level ground. Use stakes to hold lumber in place.

• 6

  Use four pieces of lumber laid out in the configuration you have chosen. Use the chalk to mark where the lumber will need to be cut and where the angles for the roof will be.

• 7

  Make the cuts and then use these pieces as the templates for the rest of your trusses.

• 8

  Trace two "triangular" and "doglegs" shaped brackets on a cardboard. Use the pattern to create the brackets out of plywood.

Assembling the Trusses

• 9

  Using the stakes on the ground to keep the trusses in place, assemble them on the ground.

• 10

  Using penny nails, attach braces to the trusses' joints. You can tie strap metal around them if you want to make them more secure.

• 11

  Secure a 2-by-6 inch board between the dogleg braces which will act as a stiffener or joist.

Raise the Trusses

• 12

  Lift the trusses into position. Make sure they are straight before attaching them to the joist.

• 13

  Use a temporary brace to secure the trusses as you are building the roof. This can be removed when the sheathing is added.

• 14

  Secure ¾-inch plywood on to the trusses. This may need to be thicker if you live in an area that gets a lot of snow.

• 15

  Cover with waterproof material. The roof will be finished by shingles of your choosing.