Common Cedar Shake Roof Problems
Cedar is a natural material that weathers over time. Understanding the specific ways cedar shakes fail helps you catch problems early — before minor damage becomes expensive structural repair. If your cedar shake roof is leaking, the cause is usually one of these five issues:
1. Split and Cracked Shakes
Cedar shakes expand when wet and contract when dry. Years of this cycle cause the wood grain to split along natural fault lines. UV exposure accelerates splitting by breaking down lignin, the natural glue that holds wood fibers together. Splits that run parallel to the grain allow water to reach the underlayment. A few split shakes are normal on an aging roof and easy to replace individually. Widespread splitting across the entire roof suggests the wood has reached the end of its service life.
2. Curling and Cupping
Shakes curl upward at the edges or cup (curve inward like a trough) when the top surface dries faster than the bottom. Poor attic ventilation is the most common cause — trapped moisture from below keeps the underside damp while the sun dries the top. Curled shakes catch wind, are prone to blow-off during storms, and create gaps where rain can enter. Mild curling can be managed by replacing individual shakes, but widespread curling usually indicates a ventilation problem that must be fixed before any repair will last.
3. Moss, Algae, and Lichen Growth
Cedar shakes in shaded, humid environments develop moss, algae, and lichen growth. Moss is the most destructive — its root system penetrates the wood grain, retains moisture against the surface, and accelerates rot. North-facing slopes and areas shaded by trees are most affected. Left untreated, heavy moss growth can reduce a cedar roof's lifespan by 10-15 years. Treatment involves soft washing (never pressure washing) followed by zinc or copper strip installation to prevent regrowth.
4. Rot and Wood Decay
Cedar has natural oils (thujaplicins) that resist rot, but these oils deplete over time. Once depleted, the wood becomes vulnerable to fungal decay — especially on the underside where moisture lingers. Rotted shakes are soft, spongy, dark, and crumble when probed with a screwdriver. Rot is not repairable — affected shakes must be removed and replaced. If rot has spread to the roof deck or underlayment beneath, those layers must also be repaired before installing new shakes.
5. Missing or Blown-Off Shakes
High winds, especially during storms, can lift and blow off cedar shakes — particularly those that have curled, loosened, or lost their nail grip. Missing shakes expose the underlayment and deck to direct rain, UV, and debris. Even one missing shake can allow water intrusion that damages the deck below. Replace missing shakes as soon as possible. After any major storm, inspect the roof (from ground level with binoculars, or from a ladder at the eave) and check the yard for dislodged shakes.
How to Replace Damaged Cedar Shakes
Replacing individual cedar shakes is a manageable DIY project for homeowners comfortable working on a roof. The technique is the same whether you're dealing with splits, rot, or missing shakes. Here's the complete process:
Roof Safety
Cedar shake roofs are slippery when wet and can be fragile when aged. Never walk on a wet cedar roof. Wear soft-soled shoes to avoid cracking shakes. Use a sturdy ladder and roof brackets or a harness on steep pitches (above 6/12). Work on dry days with no wind. If your roof pitch is steeper than 8/12 or higher than two stories, hire a professional — no repair is worth a fall.
Assess the overall roof condition
Before replacing individual shakes, evaluate the entire roof to understand the scope of work. Count the number of damaged shakes and check if the damage is localized or widespread. From the attic, inspect the underlayment and deck for rot, water stains, or daylight showing through. If more than 20-30% of shakes need replacement or the underlayment is compromised, individual repairs are not cost-effective — you need a professional re-roofing job. For localized damage (a few dozen shakes), DIY repair is practical and saves significant money.
Gather materials and tools
You need: replacement cedar shakes (match the grade, thickness, and species — Western Red Cedar is standard), a shingle ripper or flat pry bar, a hacksaw blade, a hammer, stainless steel or hot-dipped galvanized roofing nails (6d or 8d), a nail set, a wood block, clear polyurethane caulk, and a wood preservative. Buy 15-20% more replacement shakes than you think you need — you will break some during fitting. Never use plain steel nails on cedar, as they corrode and leave black stain streaks on the wood.
Remove and replace damaged shakes
Work from the bottom of the roof upward. For each damaged shake: use the shingle ripper to cut the nails, split and remove the old shake, trim the replacement to fit (3/8 inch narrower than the gap), slide it into place, and nail it with two nails positioned so the overlapping course above covers the nail heads. Leave 1/4-inch gaps on each side for wood expansion. Use a wood block and hammer to tap the shake into its final position without splitting the wood.
Apply wood preservative to repaired areas
After all replacements are complete, apply a quality cedar-compatible wood preservative (such as TWP, Cabot Australian Timber Oil, or Olympic WaterGuard) to the new shakes and surrounding area. New cedar is lighter in color and more vulnerable to UV and moisture until it develops its natural silver-gray patina. The preservative protects against rot, UV damage, and moisture absorption. Reapply preservative to the entire roof every 3-5 years for maximum lifespan.
Your cedar shake repair is complete. Inspect the repaired area after the next rain to verify no leaks. Schedule annual roof inspections to catch future damage early.
Pro Tip
Cedar Shake Maintenance & Preservation
Cedar shake roofs require more maintenance than asphalt shingle roofs, but proper care can double their lifespan. Follow this maintenance schedule:
Annually: Inspect and Clean
Remove debris (leaves, pine needles, branches) from the roof surface and valleys. Clear gutters and downspouts. Inspect for split, curled, rotted, or missing shakes. Trim tree branches that overhang or touch the roof — branches trap moisture and shade encourages moss. Check for moss or algae growth and treat if present.
Every 3-5 Years: Preservative Treatment
Apply a quality oil-based wood preservative with UV inhibitor and fungicide. Products like TWP (Total Wood Preservative), Cabot Australian Timber Oil, or Ready Seal are proven choices for cedar roofs. Clean the roof first with oxygen bleach solution, let it dry completely, then apply preservative by spraying or back-brushing. This replenishes the natural oils that cedar loses over time and is the single most important thing you can do to extend roof life.
As Needed: Moss Treatment
Soft wash (low-pressure spray + oxygen bleach or zinc sulfate solution) to kill moss and algae. Never pressure wash cedar — high pressure destroys the wood grain, strips natural oils, and shortens lifespan dramatically. After treatment, install zinc or copper strips along the ridge line to prevent regrowth. Zinc strips are cheaper ($0.50-1.00/linear foot) and effective for 15-20 years.
Never Pressure Wash Cedar Shakes
Pressure washing is the most common mistake homeowners make with cedar roofs. High-pressure water strips the soft wood grain, creates furrows that trap moisture, removes natural protective oils, and can crack shakes. Even "low pressure" settings on consumer pressure washers (1,500+ PSI) are too aggressive for cedar. Always use a garden hose with a soft wash chemical (oxygen bleach or dedicated cedar cleaner) applied with a pump sprayer.
Recommended Products for Cedar Shake Repair
These products are specifically suited for cedar shake maintenance and repair. Wood preservatives, moss prevention, and cleaning products are the three essentials every cedar roof owner needs:
Ready Seal 512 Natural Cedar Stain & Sealer
$60 – $80 (5 gal)Oil-based wood stain and sealer formulated for cedar. No primer needed, won't leave lap marks, and can be applied in any temperature. The go-to preservative for cedar shake roofs.
- No back-brushing required — spray and walk away
- UV and mildew resistant
- Semi-transparent finish preserves natural cedar grain
- 5-gallon bucket covers ~500 sq ft
ZincShield Zinc Strip for Moss Prevention
$15 – $25Install along the ridge line to prevent moss and algae regrowth. Rainwater washes zinc ions down the roof, creating a hostile environment for moss — lasts 15-20 years.
- 2.5" x 50 ft roll — covers one ridge line
- Nail-on installation — no adhesive needed
- Works on cedar, asphalt, and slate roofs
- Prevents moss regrowth for 15-20 years
Wet & Forget Moss, Mold & Mildew Remover
$35 – $45 (2 × 0.75 gal)Spray-on moss and algae remover that works with wind and rain over time — no scrubbing or pressure washing needed. Safe for cedar shakes.
- No scrubbing or rinsing required
- Safe for all roof types including cedar
- Bleach-free — won't discolor wood
- Results visible in 1-2 weeks
Cedar Shake Repair Costs
Cedar shake is a premium roofing material, and repair costs reflect that. Individual shake replacement is very affordable as a DIY project, but professional labor adds significantly due to the time-intensive nature of working with individual wood pieces:
Cedar Shake Roof Repair Costs (2026)
| Repair Type | DIY Cost | Professional Cost |
|---|---|---|
| Individual shake replacement (per shake) | $10 – $20 | $150 – $400 |
| Ridge cap repair | $50 – $150 | $300 – $800 |
| Moss/algae treatment (per sq ft) | $0.10 – $0.25 | $0.20 – $0.50 |
| Wood preservative application (whole roof) | $200 – $500 | $500 – $1,500 |
| Full cedar shake replacement (per sq ft) | Not recommended | $12 – $25 |
Costs are national averages. Cedar shake prices vary by region — Western Red Cedar is most expensive but lasts longest. Steep or high roofs add 20-40% to professional labor costs.
Pro Tip
Cedar Shake Repair vs Replacement
Knowing when to repair vs replace your cedar shake roof prevents you from wasting money on repairs that will not last:
Repair When...
- Less than 20% of shakes are damaged
- Damage is from a specific event (storm, fallen branch)
- Underlayment and deck are dry and solid
- Roof is under 25 years old
- No widespread rot or soft spots
- Curling is limited to specific areas, not the whole roof
Replace When...
- More than 30% of shakes are split, rotted, or missing
- Widespread curling across the entire roof surface
- Deck is soft, sagging, or rotted (visible from attic)
- Roof is over 30 years old with no prior preservation treatment
- Multiple active leaks in different areas
- Previous repairs keep failing within 1-2 years
Pro Tip
When to Hire a Professional
Individual shake replacement is DIY-friendly, but several situations call for a professional cedar roof specialist:
When to Call a Professional
- More than 20-30% of shakes need replacement — indicates systemic roof failure requiring professional re-roofing
- Rot has reached the roof deck or structural rafters — requires deck repair or sistering of rafters before new shakes can be installed
- Roof pitch is steeper than 8/12 or the building is higher than two stories — steep-slope work requires professional safety equipment
- Valley, ridge, or hip repair — these complex intersections require proper flashing integration and waterproofing technique
- Insurance claim for storm damage — a professional inspection report and estimate strengthens your claim significantly
- You want a full preservative treatment on a multi-story home — working on steep roofs with spray equipment is hazardous for homeowners
Related Guides
Shingle Roof Repair
Complete guide to asphalt shingle repair — the most common roofing material in the US.
Read GuideSlate Roof Repair
Another premium natural roofing material with similar longevity to cedar shake.
Read GuideStorm Damage Roof Repair
What to do when wind, hail, or fallen debris damages your cedar shake roof.
Read GuideFrequently Asked Questions
Written by
HomeRepairBase Editorial Team
Our team of home improvement experts and licensed contractors creates detailed repair guides, cost breakdowns, and troubleshooting tips to help homeowners tackle structural issues with confidence.