The type of plywood you use for roofing is typically exterior-grade plywood with a thickness of 1/2 inch to 5/8 inch. This plywood serves as the base layer under your shingles or other roofing materials. It must be strong enough to hold nails and support weight. It also needs to resist water and weather damage. Most roofers choose plywood rated for outdoor use because it can handle rain and sun exposure.
What Makes Roofing Plywood Different?
Roofing plywood is not the same as regular interior plywood. It has a special coating that resists moisture and rot. The wood is bonded with waterproof glue. This glue keeps the layers from separating when wet. Your roof stays strong even during heavy rain or snow.
Most roofing jobs need plywood rated CDX or ACX. The C and X grades mean it can handle outdoor weather. These grades cost more than interior plywood, but they last longer.
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How Thick Should Roofing Plywood Be?
For most homes, 1/2 inch plywood works fine. Some roofers use 5/8 inch for extra strength. The thickness depends on how far apart your roof trusses are spaced.
If your trusses are 16 inches apart, use 1/2 inch plywood. If they are 24 inches apart, use 5/8 inch plywood. This keeps your roof from sagging under weight.
Plywood Vs. Other Materials
Some newer roofing systems use OSB or steel decking instead of plywood. OSB is cheaper but absorbs water faster. Steel decking is strong but costs more. According to RubyHome, the average roof replacement cost is $9,526, and the material choice impacts this price. Asphalt shingles are the most common choice, used by about 80% of homeowners, according to industry data.
| Material | Cost Per Sheet | Water Resistance | Lifespan |
|---|---|---|---|
| Exterior Plywood | $35-$55 | Good | 30+ years |
| OSB | $20-$40 | Fair | 20-25 years |
| Steel Decking | $50-$80 | Excellent | 40+ years |
Installation Tips
Always check that your plywood is dry before installing shingles. Wet plywood can warp and cause leaks. Nail it down every 8 inches along the edges. Space nails 12 inches apart in the middle. According to This Old House, roof installation costs range from $4 to $40 per square foot depending on materials used. The average U.S. roof size is 2,647 square feet or 26.47 squares, so choosing the right plywood matters for your budget.
Make sure your plywood has proper ventilation underneath. Air flow helps prevent moisture buildup. This keeps your roof healthy for many years. According to industry data, most roofs last between 25 to 50 years with proper maintenance.
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Contact a qualified roofing contractor for expert guidance on roof repair, replacement, or installation.