Can you use plywood as roofing?

Question

I've seen buildings where plywood was used as both wall sheathing and siding. T-111 is commonly used this way, for example.

Would it work to do the same thing on a roof?

I assume it wouldn't last decades, but maybe its lifespan is enough for certain short-lived projects.

I guess seams would be difficult, so it may be limited to a single sheet, so only very small roofs.

I also suspect that a steeper slope might be important, so it sheds debris and water easily. And maybe facing the sun, so it dries out faster.

With all that in mind, maybe we're only talking about a small woodshed or a place to store tools. Still, it seems like it could be useful within all these constraints.

Would marine plywood make a difference?

Answer 1

Plywood absorbs water and is not a sealing material, period. You can use it as base for ruberoid roof, but not as the layer exposed to the rain.

When exposed to rain, wind and sun plywood will cycle through absorbing water and drying out and this will wear out the most outer layer in no time so that it cracks and the damage then proceeds to the next layer of plywood.

In case you want a cheap roof for a tools storage you can cover the plywood with one layer of ruberoid - it will last something like 5-10 years and the plywood can then be reused.

Answer 2

You can use any cheap plywood or even particle board as a short term sheathing on a shed roof, but cover it with a layer of rolled roofing. As Sharptooth said, it will delaminate in no time if not covered. Roll Roofing is inexpensive and easy to install. Good Luck Jay.

Answer 3

My father built a home with a plywood roof that lasted at least 30 years with no issues before it was sold. He bedded the overlapping sheets with tar and nailed strips bedded in tar on the seams. He painted all the sheets and strips with stain(?) before assembling then stained again after it was all together. The slope was standard pitch for a ranch style and carried a heavy snow load at times but was in a moderate climate with little excessive heat. I only remember seeing him re-stain once but I could have missed a time or two. It is also possible that he may have re-bedded the seam strips along the way because that is a long time to expect tar to hold up. He is no longer around to ask and I am finding very little searching for non-traditional economical roof solutions.

Answer 4

I made a large rabbit hutch and the roof was just plywood stained with Ronseal water-based outdoor woodstain, 3 coats, with the edges done properly. I did it thoroughly and it used quite a bit of stain. It lasted well for years. I think you're supposed to apply one coat each year to keep it up to scratch, which I didn't actually do, but would be better. But even without that it did well for several years. The stain dries pretty quickly.