How to Roof Over Wood Shingles
- 1). Install furring strips over the old wood shingles. Use a circular saw to cut these thin strips of wood to length, and run them horizontally across the rooftop, from one end to the other. Position the strips about 2 inches apart and run them from the base of the roof to the peak. Nail the furring strips in place with roofing nails driven with a hammer every 16 inches apart.
- 2). Roll a strip of roofing felt along the base of the roof. Tack it into place with a few nails just to keep it from blowing away while you install the shingles. Fasten your shingles over the roofing felt; drive the nails through the felt and into the furring strips. Cut the roofing felt with industrial scissors.
- 3). Install your first shingle course along the base of the roof. Shingles are generally tapered in thickness, with the thicker end being the base. Position the shingles properly, with the thicker end toward the base of the house and the narrower end toward the roof peak. Nail each shingle to the furring strips with two nails. Drive the nails ¾ inch from each edge of the shingle, and 1 inch above the shingle's exposure, or the portion of the shingle that will remain visible after the shingle course above is installed. Leave about 1/8 inch between each shingle to allow for expansion.
- 4). Fasten two layers of material on the first shingle course. Position the first layer so that the base of the shingle extends ½ inch beyond the fascia; and fasten the second layer so that the base extends ½ inch beyond the base of the first layer. Stagger the seams between these two layers of shingles to create greater water resistance. Where necessary, use a utility knife to trim your shingles to width. To make angle cuts, mark the shingle with a pencil and use a miter box saw to make the cut.
- 5). Mark the baseline of your next shingle course and use a tape measure and chalk line to extend this guideline across the roof. The specific exposure of the shingles will vary depending on the size of material you are using. Refer to the shingle manufacturer's recommendations regarding the proper exposure for the shingles you are installing.
- 6). Fasten your next course of shingles, following the chalk line guide. Position each shingle with the base resting on the chalk line and fasten them into place. Stagger the seams between one shingle course and the next to increase water resistance.
- 7). Work your way up. When you need to, roll out another row of roofing felt. Overlap the layer of felt beneath by 2 inches and tack it into place. Leave a 4-inch overlap where there are two adjacent pieces of felt.
- 8). Install roofing felt and shingles until you have shingled the entire roof section, then repeat the process on all other sections.
- 9). Cut and install a strip of roofing felt at the peak of the roof. Fasten specialized hip and ridge units along the roof peak. These prefabricated pieces consist of two shingles cut at angles and fastened together with concealed nails to create a single, peaked unit. The seams on the hip and ridge units should be staggered. Nail the hip and ridge units in place with two corrosion-resistant roofing nails driven in the portion of the unit that will be covered by the adjacent hip and ridge unit.
Source...