Building greener on a budget: can we safely use mixed-size plywood? – GreenBuildingAdvisor

Hello Folks,

We’re taking on the challenge of building our first home and garage in the Northeast (climate zone 6a), and doing our best to keep costs low while still making sure the structures are solid and durable. My questions are about whether reclaimed, irregularly sized plywood can be safely used for sheathing and subflooring—especially when paired with advanced framing techniques like 24-inch on-center spacing.

There’s a factory nearby that makes plywood items and will sell us the remaining trimmed plywood sheets at a real discount. They’re straight and flat, but come in irregular sizes. All sheets are 4 feet long, but their widths vary from 32” to 36”.  Bundles are available in 1/2″, 5/8″, or 3/4″ thicknesses.

We’ve reviewed expert sources on sheathing and subflooring, but haven’t found clear answers to the following questions:

1.     Are there any serious concerns with using 5/8″-thick, variable-width (32″–36″) plywood as wall and roof sheathing on a single-story garage framed with 2×4 studs spaced 24” on center?

2.     Are there any serious concerns with using 5/8″-thick, variable-width (32″–36″) plywood as wall and roof sheathing on a 2-story home framed with 2×6 studs spaced 24″ on center?

3.     We’re using Advantech for the first floor. But for the second story, are there any serious concerns with using 3/4″-thick, variable-width plywood (32″–36″) as subflooring over joists spaced 24″ on center? We’ll be installing pine boards as the finished flooring on top.

Any guidance, experience, or red flags to be aware of would be greatly appreciated!    Thanks in advance!