How to Give an Exterior Roof More Pitch

Remove portions of the old roof to expose the top plates of the walls above the load-bearing studs. This may require removing the entire roof, including shingles, roof deck and rafters. You need to expose the tops of the wall where the new rafters or trusses will rest.

Purchase trusses, rafter units built on the ground, that are higher than the supports of the previous roof. By extending the peak of the building higher, you create more of a slope -- or pitch -- on the roof.

Install the trusses on the walls of the building. The truss rests on the plate directly above the wall stud. This aligns the wall stud with the rafter or truss to transfer the weight of the roof directly to the foundation. Fasten the trusses to the wall plate using 16d nails driven at an angle through the truss into the plate.

Cover the trusses with 1/2-inch plywood, which serves as the roof deck. Nail the decking in place using 8d nails.

Add roofing material to finish the new roof project. Shingles are among the most common but metal roofing or roll roofing are other options. Apply shingles starting at the bottom of the roof, and add courses of shingles working up the slope of the roof.