How to Replace a Split or Missing Cedar Shake Without Damaging the Roof
Split out the broken shake, cut the hidden nails with a ripper, and slide a new one in with a proper keyway gap.
- Advanced
- 30 to 60 minutes per shake
- Updated
The short answer
To replace a cedar shake, split the damaged shake into pieces with a chisel and remove them, cut the hidden nails with a shake ripper (slate ripper), trim a new shake about 3/4 inch narrower than the opening so it leaves a keyway of about 3/8 inch on each side, slide it up to the correct exposure, and fasten it with two galvanized or stainless nails driven where the course above covers them, or sealed if exposed. Only work dry, with fall protection.
Cedar shake roofs are common on older Fraser Valley homes, and a well-kept roof can last decades. Over time, individual shakes split, curl, crack from branches, or rot at the edges from moss and trapped needles. A single broken shake leaves an opening for water, but a repair is possible without redoing the roof, because each shake is just slipped under the course above and nailed.
What makes the repair tricky is that the nails are hidden. Each shake is nailed near its top, under the two courses above, so you cannot simply pull it out. You need to split the old shake out and cut the nails with a shake ripper, a long flat tool with a hook that slides under the course above and cuts the nail shanks. For how a whole cedar roof is laid, see how to install cedar shakes.
Do the work in dry weather, and go gently. Old shakes are brittle, and lifting the course above too far splits it. If many shakes are cracked, curled or rotted, repair may only buy time, and it is worth getting the whole roof assessed. See check the roof after a windstorm if damage followed a storm.
Tools
- Shake ripper (slate ripper) with a long flat hook
- Wood chisel and hammer
- Roofing hatchet or hammer
- Handsaw or utility knife for trimming
- Pry bar
- Caulking gun
- Extension ladder with stabilizer
- Roofing harness, rope and anchor
Materials
- Matching cedar shake of the same grade, thickness and length
- Hot-dip galvanized or stainless steel nails, commonly 3d to 5d box or shingle nails for shakes (confirm size for the product)
- Roofing sealant or asphalt cement for any exposed nail heads
- Replacement felt strip if the interlay is torn
Safety first
- Cedar shakes are slippery when damp, mossy or frosty, and aged shakes are brittle and can split under a boot. Do not walk a wet or mossy shake roof.
- WorkSafeBC requires fall protection where a fall could be 3 metres (about 10 feet) or more, and many shake roofs are steep. Use a harness and anchor, and a roof ladder if the pitch demands it.
- Wear eye protection when splitting and cutting wood and nails, and keep off the roof in wind.
- Check local fire rules. Many municipalities restrict untreated wood roofing, and replacement pieces may need to be fire-treated.
Step by Step
Step 1: Pick a dry day and set up safely
Cedar shakes that are wet, mossy or frosty are dangerously slippery, and brittle in freezing weather. A warm, dry day is best. On a steep roof, a roof ladder or anchor system is needed, and if you are not equipped for that, call a roofer.
Watch out: Do not rely on footing alone on a shake roof. It can be as slippery as ice when damp.
Step 2: Identify the damaged shake and check the felt
Measure the exposure, the visible length of the course, and note the width of the gap. Check whether the damage is just the shake, or whether the shakes above and beside it are also cracked or rotted. Wood that is black and soft at the edges suggests a larger problem.
Step 3: Split out the old shake
Set the chisel along the grain and tap it to split the shake lengthwise, then pull the pieces out with pliers or your fingers. Splitting it is easier than trying to pull it out whole, which can crack the neighbours. Take care not to tear the felt.
Do not pry against the shakes above. Old cedar is fragile.
Step 4: Cut the nails with a shake ripper
The nails that held the old shake sit under the course above it. Slide the ripper in along the gap with its hook pointing up, feel for the nail, catch it and tap the ripper downward to shear the shank. Repeat for each nail, then remove the stubs left in the deck, or flatten them so they do not snag the new shake.
Check that nothing is left that could puncture the new shake or the felt.
Tip: If a nail will not cut, use a pry bar with a wooden block to lift the course above just a little, never more than needed.
Step 5: Check the felt and deck
Interlay felt is a strip of roofing felt between courses. If it is torn, slide a new piece under the course above and tuck it in. If the deck or the spaced boards are soft or dark, stop and have the framing checked, since replacing the shake will not cure rot. See how to inspect a roof deck.
Step 6: Trim a new shake to fit
Shakes are laid with small gaps between them, called keyways, commonly about 3/8 inch and no more than 5/8 inch. Measure the opening between the neighbouring shakes, subtract two keyways, and that is the width of the new piece. Cut the new shake so those gaps remain, and so its joints do not line up with the joints in the course above or below, which should be offset by at least 1-1/2 inches. Trim with a saw, and split the width if necessary along the grain.
Bevel the top corners slightly so it slides under the course above without catching.
Step 7: Slide the shake into place
Push it up until the butt lines up with the course around it. The exposure should match the rest of the roof, commonly 7-1/2 inches for 18 inch shakes and 10 inches for 24 inch shakes, but match what is there. Do not force it. A shake that is too wide will split or push its neighbours.
Step 8: Fasten it so the nails stay hidden or sealed
The best fastening is hidden: use a block and a thin pry bar to lift the course above just enough to drive two nails about 3/4 inch in from each edge, then let it down. If that is not possible, drive two small galvanized nails through the exposed butt end of the new shake, about 1 inch above the butt line of the course above it, and cover each head with a dab of roofing sealant. Use only hot-dip galvanized or stainless nails, since ordinary steel rusts and stains cedar.
Drive nails snug, not hard. Overdriving splits the shake, and a proud nail lifts the course above.
Shakes, Shingles and Matching
Shakes are thicker and split with a rough face, and shingles are thin and sawn smooth on both faces. Replace like with like, in the same length and thickness, or the repair stands out and sits at the wrong height. A dealer can match a grade, and used or salvaged shakes from a hidden slope sometimes blend better with a weathered roof.
Fire Rules and Fire Treatment
Many BC municipalities regulate wood roofing because of wildfire risk. Some require fire-retardant treated shakes, and some prohibit new wood roofs outright. A small repair usually uses matching material, but check with your municipality and your insurer before replacing a large area.
Common Mistakes
- Prying against the shakes above. Old cedar is brittle, and forcing it splits the neighbours and turns one repair into several.
- Making the new shake too wide. It binds, splits, or pushes the neighbours. Leave keyways of about 3/8 inch.
- Lining up joints. Keyways that line up between courses let water straight through. Offset them by at least 1-1/2 inches.
- Using ordinary nails. They rust, stain the wood and fail. Use hot-dip galvanized or stainless steel.
- Leaving cut nail stubs in place. They puncture the new shake or the felt.
- Working on a wet or mossy roof. Shakes are extremely slippery, and a fall is the real risk.
When to Call a Professional
Call a roofer if the roof is steep or high, if many shakes are split, curled or rotted, if the deck or felt is damaged, or if moss has taken hold over large areas. A single broken shake is one thing, while widespread failure is a sign that the roof is approaching the end of its life.
A roofer with cedar experience can also advise on fire rules, matching shakes and whether repair or replacement makes sense, see how to install cedar shakes for what a new roof involves.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Roof Repair service or the towns we cover.
How to Replace a Cedar Shake: Questions
How do you replace a cedar shake on a roof?
Split the damaged shake out with a chisel, cut the hidden nails with a shake ripper slid under the course above, slide a new shake in trimmed about 3/4 inch narrower than the opening so a keyway of about 3/8 inch remains on each side, and fasten it with two galvanized or stainless nails driven under the course above, or face nailed and sealed if you cannot reach.
What is a shake ripper?
A shake ripper, also called a slate ripper, is a long flat steel tool with a hooked end. You slide it under the course above, hook the nail that holds the old shake, and strike it with a hammer to cut the nail shank. It lets you remove a shake without lifting and breaking the ones above it.
How far apart should cedar shakes be?
Gaps between shakes in the same course, called keyways, are commonly about 3/8 inch, and no more than 5/8 inch, so the wood can swell when wet without buckling. Keyways in adjacent courses should be offset by at least 1-1/2 inches so water cannot run straight through. Check the guidance for your product.
What nails should I use on cedar shakes?
Use hot-dip galvanized or stainless steel nails, since ordinary steel nails rust and stain cedar, and the tannins in cedar corrode them quickly. Stainless is preferred in very wet or coastal conditions. Each shake takes two nails, placed about 3/4 inch from each edge and high enough to be covered by the course above.
Is it worth repairing a cedar shake roof?
Yes, if the damage is local and the rest of the roof is sound. Replacing a few broken shakes is inexpensive compared with a new roof. But if many shakes are split, rotted or worn thin, or moss has damaged large areas, repairs are a short-term measure and the roof may be nearing replacement.
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This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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