Cedar shake roofs are known for their rustic charm, natural insulation properties, and long-lasting durability. However, to get the most out of these benefits, proper installation is critical. Whether you’re a homeowner interested in understanding the process or a contractor brushing up on best practices, this comprehensive guide will walk you through every essential step of a cedar shake roof installation.
What Is a Cedar Shake Roof?
Cedar shakes are wooden roofing materials made from split logs, typically western red cedar. Unlike shingles, which are sawn and uniform, shakes have a more rugged, hand-split appearance, giving the roof a unique, textured look.
Cedar shake roofs are not just about aesthetics—they also offer excellent durability, natural resistance to insects and UV rays, and insulation advantages. However, because wood is a living material, meticulous installation practices are essential to prevent issues like premature wear, leaks, and rot.
Pre-Installation Considerations
Before starting any cedar shake roof installation, there are critical factors to evaluate:
1. Climate Suitability
Cedar shakes are well-suited for various climates but require additional care in high-moisture or fire-prone areas. Treatments for fire resistance (Class B or Class A with additional underlayments) and preservatives are often necessary.
2. Building Codes & Permits
Local codes may dictate specific requirements for cedar roofing. Check with your city or county building department to ensure compliance.
3. Material Selection
Choose high-quality, certified cedar shakes. Look for products labeled “Premium” or “#1 Grade” with minimal defects. Options like pressure-treated or kiln-dried shakes offer added resilience.
Tools and Materials You’ll Need
- Cedar shakes (standard length is 18” or 24”)
- Felt or synthetic underlayment
- Cedar breather or ventilation mat
- Stainless steel or hot-dipped galvanized nails
- Chalk line
- Hammer or pneumatic nailer
- Utility knife
- Roofing hatchet
- Ladder and safety gear
Step-by-Step Cedar Shake Roof Installation
Step 1: Prepare the Roof Deck
Ensure the deck is clean, dry, and in good condition. A plywood or spaced sheathing deck can be used, but spaced sheathing (skip sheathing) is more traditional and allows for better air circulation under the shakes.
Step 2: Install Underlayment
To protect against moisture, install a layer of 30-pound asphalt-saturated felt or a modern synthetic underlayment. In cold climates, install an ice and water shield at eaves and valleys.
For enhanced longevity, many professionals install a “cedar breather” or air mat to allow airflow beneath the shakes, which helps prevent moisture buildup and rot.
Step 3: Chalk Guidelines
Use a chalk line to mark horizontal lines across the roof at intervals equal to the exposure (typically 7.5” for 18” shakes or 10” for 24” shakes). These lines keep the courses level and evenly spaced.
Step 4: Start the Starter Course
Install a double starter course along the eave edge. The first layer should be flush with the edge, while the second course should be offset by half a shake to cover the gaps.
Ensure all shakes in the starter row are thick and laid tightly together for a solid base.
Step 5: Install Shakes in Courses
Begin laying the shakes from the bottom up. Each course should:
- Be spaced with a 3/8” to 5/8” gap between shakes to allow for expansion.
- Overlap the joints of the row below by at least 1.5”.
- Use two nails per shake, placed about 3/4” in from each edge and 1.5” above the exposure line.
- Avoid lining up vertical joints from one row to the next—stagger them by at least 1.5”.
Use longer shakes to cover hips, ridges, and valleys for added weather protection.
Step 6: Install Flashing and Valleys
Metal flashing must be installed in valleys, around chimneys, vents, and skylights. For valleys, use open metal flashing with shakes trimmed and spaced about 2” from the valley centerline on each side.
Wall flashings and step flashings should be integrated as you install each course.
Step 7: Cap the Ridge and Hips
Use specially cut ridge caps (also cedar) installed with a double course underneath. Overlap each cap and ensure it’s nailed correctly through the side (not the top) to avoid water intrusion.
Best Practices for Long-Lasting Results
1. Ventilation
Proper attic ventilation is essential to prolong the life of a cedar shake roof. Ensure your attic is equipped with both intake (soffit) and exhaust (ridge or gable) vents to allow consistent airflow.
2. Spacing and Exposure
Incorrect spacing and exposure can lead to cupping, warping, and leaks. Follow the manufacturer’s guidelines or consult a cedar shake association such as the Cedar Shake & Shingle Bureau (CSSB).
3. Treatment and Maintenance
If the shakes aren’t factory-treated, consider applying a preservative treatment after installation. Reapplications every 5–7 years can help prevent mold, mildew, and UV damage.
Perform periodic inspections to remove debris, clean off moss or lichen, and identify any damaged or missing shakes for early repair.
Common Mistakes to Avoid
- Overdriving Nails: This crushes the shake and creates a path for water.
- Too Little Spacing: Shakes expand with moisture; insufficient gaps can cause buckling.
- Improper Flashing: Skimping on flashing or incorrect placement often leads to leaks.
- Uniform Alignment: Aesthetic appeal comes from staggered rows and varied shake sizes—avoid lining them up.
- No Starter Course: Skipping this critical first step weakens the roof’s eave line and invites moisture infiltration.
Pros and Cons of Cedar Shake Roofing
✅ Pros:
- Natural beauty and curb appeal
- Excellent insulation properties
- Renewable and biodegradable
- Withstands wind and impact well
- Long lifespan (30–50 years if installed properly)
❌ Cons:
- Higher upfront cost
- Requires regular maintenance
- Vulnerable to fire without treatment
- Installation complexity (not DIY-friendly for beginners)
When to Hire a Professional
While experienced DIYers can install cedar shake roofs, the nuances in layout, cutting, flashing, and ventilation mean even small mistakes can reduce the roof’s lifespan or effectiveness. Hiring a licensed roofing contractor ensures proper techniques, compliance with code, and access to warranties.
Look for contractors who are members of professional organizations like the NRCA or CSSB and who have prior experience specifically with cedar shake roofs.
Final Thoughts
A cedar shake roof installation isn’t just about laying down wood—it’s about precision, understanding how natural materials behave, and implementing systems to protect the home for decades. With the right materials, careful planning, and attention to detail, a cedar shake roof can elevate both the performance and appearance of any home.
If you’re considering a cedar shake roof for your next project, remember that quality in both the product and installation is key to longevity and performance.