Is OSB a suitable alternative to plywood for building a patio roof cover, or are they different materials?
Asked by Earl Harrison 
6 months ago
Last Updated: May 26, 2024
I’m checking out the plans for my patio project and I want to double-check if I’m on the right track. It mentions that the roof for my patio cover should be made of 1/2-inch plywood. I’m wondering though, is OSB the same as plywood or are they different? I’m thinking of getting 19/32 OSB – would that work?
Osb costs less than plywood, it’s a different lamination style. I’ve had 4 roofs repaired and they always used 1/2 osb.
They might prefer plywood because it can better withstand moisture from condensation underneath. I recommend checking with your local authority for clarification.
It should be fine either way, but it’s a good idea to confirm with the building official.
If OSB gets wet, it can fall apart, so if your patio roof leaks, you may need to replace the OSB. The previous owner of our house used OSB on the patio floor without gutters, causing rain to come in and create a hole. While there is a lower risk on the roof, leaks can still occur over time.
Just so you know, plywood isn’t waterproof either. If there’s a leak in either, you’ll end up with the same issue.
Hey, I never claimed it was, but it definitely doesn’t break down like OSB does.
Indeed it delaminates and falls apart. Unless it’s marine grade, the glue won’t be water-resistant.
I agree with you. Wet Plywood is the way to go, even though it may deteriorate, it will still last longer than wet osb.
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Feel free to make your own choice on this. After all, this isn’t North Korea.
Exactly, Mana. In my area, we often add whole sections to our houses without bothering with permits, unless we’re in the city limits or visible from the main road.
In response to your question…no, they are not identical. OSB consists of compressed wood particles while plywood is made up of multiple thin sheets. OSB will expand if exposed to moisture.
You have the option, but it’s probably not the best idea. Like others have pointed out, it’s less water-resistant, so it will absorb moisture and break down more quickly. It also lacks the structural integrity of plywood and isn’t as good for nails.
In home construction, it’s best to use 5/8″ thick OSB or plywood. The absolute minimum to meet code is 1/2″. In my 30 years of building custom homes, I’ve never used 1/2″ on a roof in New England.
Ah got it, I’m here in SoCal too and it’s just for a patio roof cover. The building code is 1/2 and I’m not going to overbuild since we don’t get snow here.
OSB is basically like plywood. Just double-check with your local building department to confirm that they’re okay with it. Sometimes they can be picky about materials, but in this situation, OSB and plywood are pretty much the same thing. Each has its own strengths – OSB is better in some ways, while plywood shines in others. If moisture is a concern, consider using Advantech Roof OSB. It’s top-notch when it comes to sheathing products.
I would recommend avoiding OSB for roofing projects. Over time, it is prone to leaking as caulking can deteriorate. When OSB gets wet, it tends to swell and expand. While OSB can be suitable for walls, I suggest using real plywood whenever possible. I have used OSB before, but given the choice, I would opt for plywood.
In the Midwest, they typically use OSB for roofing purposes.
I’m not sure if OSB is waterproof. You might want to consider using marine grade plywood and applying Thompson’s water seal to the cut edge. Have you thought about the value of your time? Is the potential savings on materials worth the risk of having to redo it later?