The Complete Overview of How to Install Cedar Shake Roof
Installing a cedar shake roof isn’t just about nailing wood to rafters—it’s a multi-layered system where each component serves a specific purpose. The shakes themselves, split from cedar logs, are designed to overlap in a staggered pattern, creating a self-draining surface. But the real engineering lies in the underlayment, ventilation, and flashing details. Skip the underlayment, and rot will eat through the decking. Neglect ventilation, and trapped moisture turns the attic into a sauna, shortening the shakes’ lifespan. Before the first shake lands, the decking must be inspected. Old or rotted plywood must be replaced with pressure-treated or ACQ-treated lumber—never OSB, which absorbs moisture like a sponge. The spacing between rafters should align with the shake manufacturer’s recommendations, typically 16 or 24 inches on-center. A poorly framed roof won’t just look uneven; it’ll fail under snow loads. And while cedar shakes are lightweight, improper support leads to sagging, which no amount of nailing will fix.Historical Background and Evolution
Cedar shake roofs trace back to Indigenous North American craftsmanship, where western red cedar (*Thuja plicata*) was split into thin, durable shakes using hand tools. European settlers adopted the technique, prizing cedar’s natural resistance to decay—a trait attributed to its high tannin content. By the 19th century, shake roofs became a hallmark of American rural architecture, especially in the Pacific Northwest, where cedar groves thrived. Modern cedar shake roofing evolved with industrial splitting machines in the early 20th century, standardizing thickness and taper. Today’s shakes are graded by durability (A, B, C, D), with "A" being the most resistant to splitting. Advances in chemical treatments—like fire-retardant coatings—have extended their lifespan, but purists argue that untreated cedar ages more beautifully. The craft’s endurance lies in its simplicity: no complex adhesives, just wood, gravity, and precise overlaps.Core Mechanisms: How It Works
The installation begins with the underlayment, a moisture barrier that prevents leaks before the first shake is laid. Synthetic underlayments, like those made from polyester or rubberized asphalt, outperform traditional felt by resisting punctures and UV degradation. They’re installed perpendicular to the roof’s slope, with overlaps sealed with adhesive or heat-welded seams. This layer isn’t just insurance—it’s the first line of defense against ice dams and driving rain. Shakes are installed in rows, starting at the bottom (eaves) and working upward. Each row is offset by half a shake to create a staggered pattern, mimicking nature’s randomness while ensuring water runs off evenly. Nails are driven just below the top edge of each shake, never through the bottom edge, which would create a weak point. The head of the nail should be countersunk to avoid wind uplift, and stainless steel nails are preferred in coastal areas to prevent corrosion. Proper ventilation—via soffit vents and ridge vents—keeps the attic dry, preventing the shakes from swelling or rotting prematurely.Key Benefits and Crucial Impact
A cedar shake roof isn’t just a functional choice; it’s an investment in curb appeal and longevity. Unlike asphalt shingles, which degrade under UV exposure in 15–20 years, cedar shakes last 30–50 years with minimal maintenance. Their natural texture adds depth to a home’s exterior, resisting the cookie-cutter look of synthetic alternatives. And in fire-prone regions, treated cedar shakes meet strict Class A fire ratings, offering peace of mind without sacrificing aesthetics. The environmental argument is compelling, too. Cedar is a renewable resource, and responsibly harvested shakes require fewer chemicals than asphalt. Their recyclability at the end of life further reduces landfill waste. But the real impact lies in energy efficiency. Properly ventilated cedar roofs reduce heat transfer, lowering cooling costs in summer and retaining warmth in winter. For homeowners in climates with extreme temperature swings, this translates to tangible savings.*"A well-installed cedar shake roof isn’t just a roof—it’s a statement of craftsmanship. It ages like fine wine, developing a silver patina that tells the story of the seasons."* — **James Carter, Master Roofer & Historic Preservation Specialist**
Major Advantages
- Superior Durability: Cedar’s natural oils resist rot, insects, and fungal growth better than treated plywood or OSB. When properly maintained, cedar outlasts asphalt by 20+ years.
- Natural Insulation: Wood’s thermal mass regulates indoor temperatures, reducing HVAC workload. Studies show cedar roofs can improve energy efficiency by up to 10%.
- Aesthetic Versatility: Available in natural, tannin-stained, or fire-retardant finishes, cedar shakes complement rustic, modern, and historic architectures alike.
- Low Maintenance: Unlike metal roofs, cedar doesn’t rust or dent. Periodic cleaning (every 5–10 years) removes moss and debris, extending its life.
- Eco-Friendly Profile: Cedar is a sustainable, biodegradable material. Reclaimed shakes and FSC-certified sources minimize environmental impact.
Comparative Analysis
| Cedar Shake Roof | Asphalt Shingles |
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| Metal Roofing | Wood Shingles |
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Future Trends and Innovations
The future of cedar shake roofing lies in hybrid solutions. Manufacturers are embedding UV-resistant coatings into shakes to slow graying, while nano-technologies promise self-cleaning surfaces that repel moss and algae. Sustainable sourcing is another frontier: vertical farming of cedar trees and lab-grown wood fibers could reduce deforestation pressures. Smart roofing systems, embedded with sensors, might soon alert homeowners to moisture buildup or structural stress in real time. Climate adaptation is critical. As extreme weather events increase, cedar shakes with reinforced edges and impact-resistant treatments will gain traction. In wildfire-prone zones, Class A fire-rated shakes with intumescent coatings (which expand to block flames) are already in demand. The industry’s shift toward modular, pre-fabricated shake panels—installed like large tiles—could also revolutionize DIY installations, making high-quality cedar roofs accessible to more homeowners.
Conclusion
Installing a cedar shake roof is a labor of patience and precision, but the rewards are undeniable. It’s a roof that ages with character, performs under duress, and stands as a testament to timeless craftsmanship. The key lies in the details: the right underlayment, the proper nail pattern, and an understanding of how cedar behaves in your climate. Rush the process, and you’ll pay for it in leaks, rot, or premature replacement. But execute it correctly, and you’ve created an asset that enhances your home’s value and beauty for decades. For those willing to put in the effort, the result isn’t just a roof—it’s a legacy. Every staggered row, every carefully placed nail, contributes to a structure that tells a story. And in an era of disposable building materials, that’s a narrative worth preserving.Comprehensive FAQs
Q: Can I install a cedar shake roof myself, or should I hire a pro?
A: DIY installation is possible for experienced carpenters with roofing knowledge, but cedar shakes require precision in nailing, underlayment, and ventilation. Mistakes—like improper overlaps or inadequate flashing—can void warranties and lead to costly repairs. If your roof has complex angles or exceeds 30 feet in length, hiring a licensed roofer is strongly recommended.
Q: How do I prevent moss and algae growth on cedar shakes?
A: Moss thrives in shaded, damp roofs. Install zinc or copper strips along the ridge to create a chemical barrier that inhibits growth. Regular cleaning with a soft brush and mild bleach solution (1 part bleach to 3 parts water) every 5–10 years also helps. Ensure proper ventilation to reduce moisture retention, and trim overhanging trees to allow sunlight exposure.
Q: What’s the best underlayment for a cedar shake roof?
A: Synthetic underlayments (polyester or rubberized asphalt) are superior to felt for cedar roofs due to their puncture resistance and UV stability. Look for products rated for steep-slope roofs with a minimum 30-year warranty. Avoid standard 15# felt, which degrades quickly in wet climates and can’t handle the weight of cedar shakes.
Q: How many nails should I use per cedar shake?
A: Use four nails per shake for roofs with a pitch of 4:12 to 7:12, and six nails per shake for steeper pitches (8:12 and above). Nails should be 1¼" long, driven just below the top edge of the shake, and spaced evenly across the width. Over-nailing can split the wood, while under-nailing risks wind uplift.
Q: Do cedar shakes require special treatment for fire resistance?
A: Untreated cedar shakes are Class C fire-rated, meaning they’ll ignite if exposed to direct flame. For Class A (highest) fire resistance, apply a fire-retardant treatment (like Borate or Ammonia Phosphate) before installation. Some manufacturers offer pre-treated shakes with built-in fire resistance. Always check local building codes, as fire-rated shakes may be mandatory in wildfire-prone areas.
Q: How do I calculate the number of cedar shakes I need?
A: Multiply your roof’s square footage by 280 (the number of shakes per square, accounting for waste). For example, a 2,000 sq. ft. roof requires ~560 squares (2,000 × 280). Add 10–15% for breaks, cuts, and waste. Use the manufacturer’s coverage chart, as shake sizes vary (e.g., 16" vs. 24" exposure). Always order extra for mistakes.
Q: Can I install cedar shakes over an existing roof?
A: No. Building codes prohibit installing shakes over existing shingles due to weight limits and the risk of trapping moisture. The old roof must be stripped completely, and the decking inspected for rot or damage. If the existing decking is sound, you can install a new underlayment and proceed. However, most inspectors require full removal to ensure proper ventilation and nailing.
Q: What’s the best time of year to install a cedar shake roof?
A: Ideal conditions are cool, dry weather between 40°F and 70°F. Avoid installing in humidity above 15% (shakes warp) or below freezing (wood becomes brittle). Morning installations prevent afternoon heat-induced expansion. Spring and fall are optimal, but never install during heavy rain or snow. If you must work in summer, start early to avoid midday heat.
Q: How do I ventilate a cedar shake roof properly?
A: Combine soffit vents (intake) with ridge vents or turbine vents (exhaust) for balanced airflow. The vent area should equal 1/300 of the attic’s square footage. For example, a 2,000 sq. ft. attic needs ~6.66 sq. ft. of venting. Avoid blocking vents with insulation or debris, and ensure continuous airflow along the roof’s length to prevent hot spots.
Q: What tools do I need for cedar shake roof installation?
A: Essential tools include:
- A cedar shake roofing hammer (with a curved claw for nail removal)
- Stainless steel or aluminum nails (1¼" long, 11 or 12 gauge)
- A chalk line for straight rows
- Roofing cap nails for flashing
- Safety gear (harness, gloves, non-slip boots)
- Knee pads and a pry bar for adjustments
