The ends of roof rafters that hang over the edges of walls are known as eaves. One way to make a major change in your home's appearance is to change the roof line. Extending the rafter tails to increase the width of the eaves will change the profile of the house considerably, add more protection from the elements and is a fairly simple and inexpensive process. Cutting the extensions at the correct angle is the key to a good fit.
Use an angle finder to calculate the angle on your rafter ends. Fit one leg of the finder against the bottom of the roof deck near the end of a rafter tail and align the remaining leg with the end of the rafter. Read the angle from the indicator on the finder.
Cut the end of a 2-inch by 4-inch board (or 2-by-4) to the angle you recorded on the finder. Fit the 2-by-4 alongside one of your rafter tails with the newly cut end at the top, flush against the wall. Mark the end of the rafter tail on the 2-by-4 to mark the original length of the rafter tail. Add the amount of extension you intend to add to the length of the 2-by-4 and cut it to length, cutting the same angle at this end that you used at the top end. Cut one extender to this same length for every rafter along the length of the roof on both sides of the house.
Fit one extender to the back face of each rafter so that it aligns with the original, pressed against the bottom of the roof deck with its top end pressed against the wall. Nail these extenders to the rafters with 16d framing nails. Use one nail every 6 inches along the length of the extender.
Measure the distance from the end of the original rafters to the end of the extension. Cut pieces to fill the area from the end of the original rafter to the end of the extensions. Cut the ends at the same angle you used for the extensions. Fit one to the end of each original rafter. Nail them in place as for the extenders.
Use a pry bar to remove the metal roof edge flashing. Pry it loose starting from one end and working along the edge of the roof. Measure from the edge of the original decking to the end of the extended rafters. Cut ¾-inch plywood pieces to width to fit this distance, with 1 inch extra width for overhang. Fit the plywood on top of the rafter extensions with one long edge against the bottom edge of the original roof decking.
Fit the first piece so that the front end is flush with the outside face of the gable. Mark and cut the plywood to length at the centre of the rafter that is closest to the far end. Nail the plywood to the rafters with 1 ½ inch roofing nails. Butt the next piece of plywood up to the first. Cut it to length if needed, so that it ends in the centre of a rafter and so that all end joints are supported. Add full length pieces as far as possible. Measure and cut the last piece to fit.
Nail a metal roof edge flashing along the lower edge of the new plywood with 1-inch roofing nails. Cut the edge to fit with tin snips. Roll out roofing felt to cover the new plywood. Cut it to fit along the plywood edge with a utility knife. Tuck the top edge under the bottom of the shingles above. Nail the felt to the plywood with 1-inch roofing nails with nylon washers. Use one nail every 12 inches.
Add shingles to cover the new plywood. Fold the bottom edge of the original shingles up and fit the top edge of the new shingles underneath. Nail the shingles in place with 1 ½ inch roofing nails. Use six nails per shingle.