How to Install Cedar Shingles. Cedar shingles can give your home a classic rustic look while offering long-term protection for your roof. Not only are cedar shingles good-looking, they also provide extra insulation value (in comparison to asphalt shingles) and you often can install them over your existing roofing. While shingles and shakes can be made from many different types of wood (redwood and pine are common), cedar is by far the most popular roofing material.
Determine how many shingles you will need. Measure the width of your roof, and then measure from the bottom edge up to the peak. Calculate the square footage of this section by multiplying the two numbers. For example, if your roof is 30 feet long and the distance from eave to peak is 20 feet, you will need 30 x 20 = 600 square feet to cover the section.
Repeat the calculation for each section of your roof and sum the individual square footage requirements. Add 10 percent for waste and you will have the total square footage of cedar shingles you'll need to cover your roof. Divide the total number by 100 to determine the number of "squares" of shingles you will need (shingles are sold in "squares" that cover 100 square feet).
If you are installing the new shingles over existing shingles, make sure you replace any missing nails and fasten any loose shingles to provide a solid surface for your new roof.
If your roof already has three layers of shingles on it or it's in bad shape, you should remove the existing shingles (use a crowbar or roofing shovel to pry up the existing roofing), and then cover the roof with roofing felt before shingling.
Installing Cedar Shingles
Start at the bottom edge, making sure the first row of shingles overlaps the roof edges by at least 1 1/2 inches. On the first row only, put the thick end of the shingle facing the peak. Fasten the shingles with two nails 1 inch from each side and 4 inches from the top. Space adjacent shingles 1/4 inch to 3/8 inch from each other.
Completely overlap the first row with a second course of shingles (this row and all subsequent rows with the thick end facing the edge of the roof). Ensure that this row covers the gaps between the underlying shingles by at least 1 1/2 inches.
Snap a chalk line from one side of the roof to the other to mark the top edge of the next row of shingles (you want to leave an exposure of 4 to 5 inches), and then install the new row to the mark. Be sure to leave the 1/4-inch to 3/8-inch gap between adjacent shingles and overlap the gap in the row underneath by 1 1/2 inches. Trim the shingles to the correct width at the end of a row.
Work your way up the roof, snapping chalk lines for each row, until you reach the top ridge. Install roofing felt on the peak before installing your final row of shingles.
Use a hand plane to align the edges of each shingle to match the angle where the rows meet at the peak.