How to Lay a Cedar Shake Roof
A cedar shake roof is much nicer looking than asphalt shingles and gives a natural appearance to any roof. The roof of cedar shakes lasts longer than a shingle roof. Shingles usually last from 15 to 25 years. Cedar shakes can last up to 50 years. Be aware of the difference between cedar shingles and cedar shakes. The cedar shingle is thinner than the shake and has a smooth surface. Shakes are thicker, sawn or hand split and have a more rugged appearance. In the past, cedar shakes were used more than shingles because of they were cheaper. Today, shakes are made of western red cedar and cost much more than asphalt shingles. The insulating value of a 1" cedar shake is at least twice that of an asphalt shingle, so that can reduce heating and cooling costs. The cedar shakes are more difficult to apply and are not fire resistant. Check with your local building code enforcement to see if you can use cedar shakes in your area before you start as they may be prohibited. Installing the shakes on a roof can be done by the do-it-yourselfer, but it is not an easy project.
- Decide if the roof is too steep for you. If it is and you are uncomfortable, even in a safety harness or on toe board, call professionals to do the job. Roofing is a hard job physically, so decide if you are up to it before starting the job.
- Use a nail holder in an apron around your waist. It is easier and safer when you are working on a roof. Use a nail stripper for lining up wood roofing nails ready for use. The nails are loaded into the stripper, with the nail head up, so you can put down four or five shingles or shakes at one time. It is worn on the chest with a harness and costs about $20. A shingler's hatchet is often used for asphalt shingling. Make sure it has a sliding gauge for fast, accurate checking of exposure. Wear a safety harness with a hook that attaches to any solid spot on the roof. Wear rubber soled shoes so you don't slip.
- Open the shake packages and shuffle them so sizes and colors are random and you do not end up with patches of the same colors or sizes. Install an underlayment. First nail a drip edge along the eaves. Then place an ice/water barrier material on the lower portion of the roof overlapping the drip edge. Cover the area of roof above the ice and water barrier with 15-pound felt with the bottom edge of the felt overlapping the ice and water barrier. After the felt is laid, nail drip edges along the rakes. Nail the top edges of the felt strips into the sheathing every six feet.
- Install the shakes in straight, single courses at a 9-inch exposure. The “starter course” is a row of any 12-inch wide shake. The butt (thick) end of the starter course must project ½-inch beyond the fascia/drip edge. Make sure the first course is straight. To do this, let the first one overhang the drip edge and nail it down. Place another shake the same way at the other end of the roof. Tack a string to the butt end of both shakes and align the butts of the intervening shakes on the string. Snap a chalk line every course. Space the shakes 3/8-inch apart. Apply a second course of shakes directly over the starter course so the butt of the starter course is even with the butt of the second course. The joint between two shakes in one course should never be closer than 1 ½ inches to a joint below or above it. Always overlap the shakes so no joint is open to the weather and always cover each nail as you continue up the roof. Start the rest of the roof with the first full course of shakes. Apply an 18-inch strip of 15-pound roofing felt over the top portion of the shake. The bottom edge of the felt should be positioned 17 inches up from the butt and continue up the roof, laying felt over the top portion of each consecutive row of shakes. Vary the widths and avoid creating a diagonal pattern as you work your way up the roof. Check from the ground every few courses to make sure you have varied widths and no unwanted patterns.
- Use stainless steel, hot dipped galvanized or electro-galvanized roofing nails. Secure the shakes with 2-inch nails, no matter how wide the shakes are.
- When you nail the final two courses on the ridge, the ends will extend above the ridge. Snap a chalk line flush with the ridge and cut all the shakes at once with the circular saw.
- Shakes must be cut in order to fit properly around vents, along the rake, in valleys, and beside flashing. Shakes should be cut with a circular saw for straight lines or with a saber saw for curves. Use only uncut factory edges kept flush along rake/gable ends.
- Flash the valleys with galvanized valley flashing and work up to the pre-bent water splash with the shakes. Cut the shakes with a utility knife. Flash any pipes or vent penetrations with a rubber fitting boot and caulk under the boot. Place the vent down and work around the pipe with each layer of shakes cutting the shakes as necessary.
- The ridge is usually a ridge vent of galvanized ridge flashing. Attach the flashing and caulk over any exposed nails with the caulk. Work up to the ridge with the shakes. When you get to the last row of shake, glue them on with the roofing caulk (called roofing bull). This covers all nails heads or holes.