I got lured by discounted osb board

[StinkyAcres]

I used OSB on the outside of my coops, I'm in Southern Ontario so not that different climate wise. They're painted three coats one both sides and have held up well. For floor though I would use either plywood sealed or lay down some tiles over the OSB

Sure, it holds up for a few years. I would think most people want a more permanent coop though. My old coop had painted OSB siding and the sides that got a lot of rain lasted less than 10 years. It crumbled when I took it off this year.

 

[Lulu-vt]

I used OSB on the outside of my coops, I'm in Southern Ontario so not that different climate wise. They're painted three coats one both sides and have held up well. For floor though I would use either plywood sealed or lay down some tiles over the OSB

Do you think the moisture from under the ground will affect the integrity of the osb? It is about 20” off the ground. Currently it’s not painted or stained.

 

[Penpal]

It will last for a while. You don't need to be in a hurry to replace it. But, I would replace it with marine board.

 

[aart]

Do you think the moisture from under the ground will affect the integrity of the osb?

It could. Not all OSB is created equally.
I'd change it out now, since your walls will be on top of it, pretty hard to change out once it rots.

 

[2 Acres]

Osb was 50% off and I bought it for the floor of my coop. It’s 7/16th. Now that I’ve put it down I’m worried that it’s going to swell and fall apart.
Should I…

A. Take it off and use plywood?
B. Paint/Seal it on both sides?
C. Attach plywood underneath the joists, add insulation and then the osb on top. (This sounds expensive)

The bottom of the coop is 20” off the ground. For the inside I plan on using a smooth surface like linoleum on top of the osb

I’m framing the walls out soon and my plan was for the walls to go on top of the edges of the osb. But if they’re going to disintegrate then the whole coop could be in jeopardy. Or am I just being dramatic?

I live in Vermont

Attach 2x4's Under the joist... As cross blocking. Space it 2 feet apart (if I'm picturing things correctly.

 

[5Australorpasaures]

If your vinyl is a one piece coverage lay before you set the outside walls for moisture barrier inside the coop protection. I don't know if OSB still comes with a rough side and a "slick" side. Slick side towards the elements and a coat of sealer to inhibit moisture absorption. The only thing is 1/2" is iffy to walk on even on 16" layout. As has been said mice will gnaw, as will raccoons but sounds like you're elevated.