How to Cut Fascia on Roof Rafters

Measure the length of the roof with a tape measure. Most roofs will require more than a single board to cover the rafters from front to back. Test the rafter ends or tails with a piece of 1-by-6 inch lumber to ensure they are properly cut so the fascia will form a straight upright face along the roof. Fit the fascia board flush against the edge of the roof where the shingles end. The fascia board may extend even with the bottom of the rafter or below it, depending on the end cut on the rafter.

Cut one end of a fascia board square with a circular saw. Measure it to end in the center of a rafter and cut a 45-degree angle facing away from the front so another fascia board will overlap it and form a smooth joint. Nail the first fascia board to the rafter tails with a hammer and 8-penny nails, starting at the back of the house. Get help; it will require two workers on ladders to hold the fascia in place and nail it.

Drive two nails into each rafter tail through the fascia board. At the 45-degree angle end, nail through the thickest part of the angle cut. Place the second fascia board with a 45-degree angle cut to overlap and nail through both fascia boards into the rafter. Repeat this process if it takes more than two fascia boards to cover the length of the roof.

Cut fascia ends differently on a hip roof. Start with a 45-degree angle with the inside part of the cut at the end of the roof edge; cut the adjoining fascia at the reverse angle, so the two boards form a 90-degree corner. Do this on all four sides of the roof. End fascia boards on a gable roof with a square end, which will be covered by trim called a rake board which runs along the triangle edge of a gable end.