How to Build a Gambrel Roof

What You'll Need
Penny nails
Temporary brace
Metal straps

If you are building or renovating your house and would like to have more storage space than you used to, you can try erecting a gambrel roof, which with its arch shape, will provide ample room to store your possessions. Read on to find out the steps to follow if you decide to beatify your home with this stylish yet practical type of roof.

Step 1 - Plan the Gambrel Roof

The first thing you should do is calculate the trusses you will need. The trusses of the roof should be 16 inches apart from one another.

Decide how high the gambrel roof will be. For example, a good height for a 36-foot wide building would be 10 feet 4 inches, but there are no restrictions. Ultimately it is up to you how tall the roof will stand. Just remember when making the calculations that the upper section of the gambrel roof typically has an angle of 30 degrees, while its lower part is slanted at 60 degrees.

Step 2 - Lay Out the Trusses

Buy the boards you will need for the construction. (The most appropriate will be 2-by-6-inch boards.) On a level plot of land, lay out four boards in a design of your choice and mark with chalk the places where you will cut and the angles you will need for the roof.

Make the cuts and use the boards as templates for the other trusses. Then take some cardboard and trace the truss angles onto it. Use the resulting patterns to create brackets from 1/2-inch plywood. You should come up with two bracket shapes–triangular and doglegs-like.

Step 3 - Assemble the Trusses

After you have cut the boards and brackets for the trusses, you need to join them together. Attach the brackets by using eight penny nails. If you aim at further reinforcing the joints, tie them with metal straps.

To finish the trusses, take a 2-by-6-inch board and secure it between the dogleg brackets to serve as a joist. 

Step 4 - Lift the Trusses into Place and Cover Them

Raise the trusses into position and having made sure each truss is plumb and straight, nail them to the joists of the lower floor.

Have a temporary brace fixed between trusses while you are building the roof. In this way the trusses will not tilt sideways and will form a strong foundation for the roof. 

For roof sheathing, cover the trusses of your gambrel roof with 3/4-inch plywood and secure it in place. (If you live in an area with heavy snowfalls, increase the thickness of the plywood.)

Place a layer of waterproof material over the plywood and finish working on the gambrel roof with shingles of your choice.

Step 5 - Build the End Walls

Cut studs for all end walls and fit them within the slope of the roof by cutting angles into the studs and notches into the angles and trusses. If you want, frame and install windows. Finally use plywood and shingles to cover the ends.