Best Plywood for Roofing: Choosing Durable Roof Sheathing

Selecting the best plywood for roofing is a critical decision that affects a roof’s strength, longevity, and resistance to weather. This guide explains plywood types, grades, thicknesses, treatments, fastening practices, code considerations, and roof-specific recommendations to help roofing professionals and homeowners make informed choices.

Plywood Type	Key Benefits	Common Use
CDX Plywood	Affordable, exterior-rated glue	Standard roof sheathing
Exterior-Grade A/B	Smoother face, stronger glue	High-end roofing underlayment
Pressure-Treated	Rot and insect resistance	Areas of high moisture
APA-Rated Structural 1/2, 5/8	Span-rated for loads	Commercial and residential roofs

Types Of Plywood For Roofing

Several plywood varieties serve as roof sheathing, but the most common are CDX exterior plywood, APA-rated structural panels, and pressure-treated plywood. CDX uses weather-resistant glue and is the standard for many residential roofs. APA-rated structural sheathing includes span ratings and performance stamps useful for code compliance. Pressure-treated plywood is used in moisture-prone areas or where direct contact with wet materials is expected.

Plywood Grades And Performance Stamps

Plywood grade affects face appearance and durability. Common grades include A, B, C, and D, where A and B have fewer defects and smoother faces. For roofing, grade matters less than structural stamp: look for APA/PS 1-09 or PS 2 stamps showing shear strength, thickness tolerance, and bonding. These stamps confirm suitability for roof sheathing and help meet building code requirements.

Thickness, Span Ratings, And Structural Considerations

Roof plywood thickness is chosen based on rafter or truss spacing and loading. Typical choices are 1/2-inch, 5/8-inch, and 3/4-inch. 1/2-inch is common for 16-inch on-center framing, 5/8-inch for 24-inch on-center or heavier loads, and 3/4-inch for long spans or commercial applications. Use manufacturer span tables or local code span charts to select the correct thickness for safety and performance.

OSB Versus Plywood For Roofing

Oriented Strand Board (OSB) often competes with plywood as roof sheathing. OSB is usually less expensive and uniform, while plywood offers better resistance to moisture-related edge swelling and higher nail withdrawal strength. In high-wind or coastal regions, plywood’s performance advantage can justify higher cost. Both materials must be APA-rated and meet code standards for roof sheathing.

Fastening, Nailing Patterns, And Installation Tips

Correct fastening improves roof diaphragm strength. Use corrosion-resistant nails, typically 8d ring shank or 8d common, and follow manufacturer spacing—commonly 6 inches on edges and 12 inches in the field for 1/2-inch panels on 16-inch centers. Stagger butt joints and leave a 1/8-inch gap between panels for expansion. Glue can be used at joints for added stiffness and to minimize wind uplift issues.

Moisture Resistance And Treatments

Plywood intended for roofs must resist delamination and rot. Exterior-grade adhesives are standard, but in wet climates consider pressure-treated panels or boards treated with water-resistant preservatives. Also use underlayment, drip edges, and proper ventilation to reduce condensation and moisture accumulation that shortens plywood life.

Building Codes, Standards, And Inspection

Local building codes reference standards for sheathing materials, span, and fastening. Inspectors look for APA stamps, correct thickness, and proper nailing patterns. The International Residential Code (IRC) provides general requirements; local amendments may mandate specific materials such as higher-grade plywood in high-wind zones. Always verify with the local building department before purchase or installation.

Cost, Availability, And Sustainability

Plywood prices fluctuate with lumber markets. CDX is typically the most cost-effective option, while specialty plywood and pressure-treated panels cost more. OSB may be cheaper but has different performance trade-offs. For sustainability, seek plywood from sustainably managed forests (FSC-certified) and consider recycled-content or engineered wood alternatives that meet structural needs.

Maintenance, Inspection, And Repair

Regular roof inspections help detect sheathing problems early. Look for sagging, cupping, or soft spots after storms. Replace damaged panels rather than patching when structural integrity is compromised. Promptly repair leaks and maintain flashing, underlayment, and ventilation to maximize plywood lifespan and reduce costly roof deck replacements.

Best Plywood Choices By Roof Type

Different roofs benefit from different sheathing decisions. For steep-slope asphalt shingle roofs, CDX or APA-rated 1/2-inch panels work for 16-inch centers, with 5/8-inch for 24-inch centers. For tile or slate roofs that are heavier, choose 5/8-inch or 3/4-inch APA-rated structural plywood. Flat roofs or low-slope roofs with membrane systems may require specialty sheathing and better moisture protection like pressure-treated or coated structural panels.

Special Situations: High Wind, Coastal, And Fire-Prone Areas

In high-wind regions, plywood with higher nail withdrawal strength and thicker panels reduce wind uplift risk. Coastal areas benefit from marine-grade or treated panels that resist salt and moisture ingress. Fire-prone zones may require treated sheathing with fire-resistant coatings or noncombustible roof assemblies; always consult local code for required materials and assemblies.

Recommendations For Purchasing And Storing Plywood

Buy panels with APA stamps and correct span rating. Inspect sheets for core gaps, face voids, or delamination before purchase. Store plywood flat, elevated off the ground, and covered to prevent exposure to rain and sunlight. Keep panels dry before installation to avoid edge swelling and glue failure.

How To Choose The Best Plywood For Most Projects

Start by assessing rafter/truss spacing, expected loads, local climate, and building code. For most U.S. residential roofs, APA-rated CDX or structural plywood in 1/2-inch or 5/8-inch thickness provides the best balance of cost and performance. Upgrade thickness or choose pressure-treated panels for heavy roofing materials, wide spans, or moisture-prone locations.

Quick Reference Table: Common Thickness Vs. Typical Use

Thickness	Common Span (On-Center)	Typical Uses
1/2 Inch	16 Inches	Standard residential shingles
5/8 Inch	24 Inches	Wider framing, heavier roof loads
3/4 Inch	Long Spans/Commercial	Heavy tile, long spans

Key Takeaway And Practical Checklist

When selecting plywood for roofing, prioritize APA/PS-rated panels, correct thickness for span, moisture resistance, and proper fastening. Verify local code, inspect materials on delivery, store panels correctly, and ensure adequate ventilation and underlayment to protect sheathing over the roof’s lifetime.

Where To Get Professional Help

Consult licensed roofers, structural engineers, or your local building department for complex or nonstandard projects. Professionals can validate span calculations, fastening schedules, and material selections to ensure compliance and long-term performance. Proper design and installation prevent costly failures and extend roof life.