Installing Cedar Shingles on Plywood: A Practical Guide

Installing cedar shingles on plywood provides a durable, traditional siding or roofing option with natural weather resistance and aesthetic appeal. This guide covers surface preparation, underlayments, fastening patterns, and maintenance to help homeowners and professionals achieve a lasting cedar shingle installation on plywood sheathing. Proper alignment, ventilation, and moisture control are essential for long-term performance.

Preparation Of The Substrate

Begin with a clean, dry plywood surface that meets local building codes. Use exterior-grade plywood with a thickness appropriate for the project (typically 5/8 inch to 3/4 inch for walls; thicker for roofs). Inspect for moisture damage, warping, or prior coatings. Replace any compromised sections. A flat, stable substrate minimizes gaps and alignment issues, ensuring proper drainage and appearance.

Materials And Tools

Key materials include pressure-treated starter strips, cedar shingles of consistent thickness, a weather-resistive barrier, and corrosion-resistant fasteners. Common fasteners are galvanized or stainless-steel nails or staples sized for cedar (generally 7d to 10d nails, depending on shingle thickness). Tools include a hammer or nail gun, chalk line, straightedge, utility knife, pry bar, metal flashing, and a shingle gauge or spacing tool to maintain uniform gaps. Stock extra shingles for cuts and replacements.

Underlayment And Weather-Resistive Barrier

A weather-resistive barrier (WRB) is essential when cedar shingles are installed over plywood. Apply a permeable WRB to allow vapor diffusion while blocking wind-driven rain. Install with the weather surface facing outward and stagger seams to reduce water intrusion. For roofs, use a roofing underlayment rated for cedar shingles. On walls, combine WRB with appropriate house wrap. Ensure gaps around outlets and vents are sealed with flashing tape or mesh for continuous protection.

Shingle Layout And Starter Course

Plan the layout to achieve a clean edge line and balanced exposure. Start at a corner or eave line. The first course should be level to create a straight reference. Use a starter strip that’s narrower than a full shingle to prevent visible end grains. The starter strip helps seal the bottom edge and provides a uniform reveal for each course. Maintain consistent exposure (the portion of shingle visible) according to the shingle manufacturer’s recommendations.

Nailing Pattern And Fasteners

Fastening cedar shingles requires patience and accuracy. Use corrosion-resistant nails or staples compatible with cedar and plywood. Drive nails at the upper edge of the shingle, about 1/4 inch from each side, and slightly above the nailing line to avoid splitting. Do not overdrive, as this may crush the wood. For roof installations, stagger nail locations between courses to reduce water intrusion. Use rubber or neoprene washers only if the system specifies them; otherwise, rely on proper sealing with flashing and WRB integration.

Shingle Cutting And Handling

Custom cuts around windows, doors, and edges should be precise. Score cedar with a sharp utility knife or use a fine-toothed saw for clean edges. Preserve the natural texture by avoiding excessive sanding. Dry-fit pieces before nailing to ensure correct alignment and spacing. Maintain a consistent gap between shingles to accommodate expansion and moisture movement.

Ventilation, Drainage, And Moisture Control

Proper ventilation behind cedar shingles helps regulate moisture and prolongs life. For walls, maintain a deliberate gap between the WRB and the shingles to allow air circulation. On roofs, ensure underlayment, flashing, and ridge ventilation work together to prevent moisture buildup. Cedar shingles expand and contract with humidity; leave small, uniform gaps to accommodate movement and prevent buckling.

Finishing Details And Flashing

Install steel or aluminum flashings at corners, valleys, and transitions to direct water away from the plywood substrate. Use continuous, corrosion-resistant flashing in areas prone to water intrusion. Seal joints where shingles meet vertical walls or roof edges with compatible sealant and flashing tape. Protect exposed edges with end caps or trim boards to improve longevity and appearance.

Maintenance And Longevity

Cedar shingles require routine inspection for loose nails, splitting, or cupping. Clean debris from gaps to prevent moisture retention. Re-staining or sealing every few years, depending on product and climate, helps maintain color and moisture resistance. Address cupping or curling promptly by resealing and, if necessary, replacing affected shingles. In high-moisture environments, expect more frequent maintenance and potential refinishing needs.

Common Issues And Troubleshooting

Common problems include cupping, warping, or nail heads pulling through. Moisture intrusion around flashing or joints can lead to decay if not corrected. If shingles dry out or split, consider a controlled resealing or replacement plan. Ensure proper ventilation and WRB integrity to minimize recurring issues. When in doubt, consult the shingle manufacturer for site-specific guidance and warranty terms.

Safety Considerations

Working on elevated surfaces requires fall protection and proper ladder use. Wear eye protection when cutting and handle shingles to avoid splinters. Follow local building codes for ventilation, fire separation, and wind resistance. Use PPE and secure materials to prevent accidents.