A gable roof is the type that a child might make on a drawing of a house. This type of design is extremely strong and sheds snow and rain very well. There are a number of variations on the basic design of the gable roof. One of these is the winged gable roof. In this type of roof design, the roof beams or joists, extend beyond the sides of the house, creating the classic overhanging eave style evident in so many of the houses in this country. Below you will find a short list of steps outlining how to build a gabled roof.
Step 1 - Measure
Carpenter’s have a favorite saying: Measure twice in order to cut once. In order to do this, you’ll need to draw the roof as viewed from the side. You will also need to decide on a slope for the roof. Once you have decided on the angle of the roof, otherwise known as the slope, measure base of your roof triangle by measuring from one wall to the opposite wall on the house. Cut this length in half and you have your midpoint. Draw a line perpendicular to the base and extend it. From the edges of the base, extend a line to the perpendicular midpoint line using the roof angle you decided upon.
Now you can use the Pythagorean Theorem from Geometry class to determine your lengths, if you drawn your triangle to scale. According to Pythagorus:
a2 + b2 = c2
In this, a is the base, b is the perpendicular line and c is the roof line. Once you have calculated the length of c, add the desired length for the “wings” on either side, but remember the original measurement, since this is where the roof joist will meet the outer wall.
Step 2: Build the Frames
Now that you know your triangle dimensions, it’s time to build the joist frames. These frames will be the same dimensions as calculated above, with the sloping roof extending your desired length beyond the end of the triangle base. You will need one frame for every two feet of roof length, in most jurisdictions. Measure and cut your bases, upright supports and joists and assemble them according to local building codes.
Step 3: Mount Roof Joist Trusses
Once you have all the frames, or trusses built, it is time to measure the between joists spacing of 2 feet (or whatever local code dictates). As you measure along the depth of the roof line, mark every two feet (or local code specification). This will be where the trusses attach to the walls. Once you have them all marked out, it is time to raise the roof. Mount the trusses per code until all are in place.
Step 4: Lay Roofing Base
Once the trusses are up, it’s time to lay the base for your roofing material. The base is ¾-inch fire-rated plywood in most locales. Again, refer to local building codes. Cover the whole of the roof, including the winged overhang. Once the plywood is laid and secured properly, it’ll be time for applying the water barrier underlayment and the roofing material.
The article above listed four steps to build a winged gable roof. Please be advised that building codes vary by locale. Before beginning this project, you should consult your local building codes.