I've been building a small cabin in the mountains for the past year or so in my spare time and finally have a sub floor laid out and screwed down. I have no time frame as to when I get a roof over the floor and with winter approaching, I'd like to get something to protect my OSB from the elements.

I am in southern california and we're supposed to have a wet winter. Not necessarily snow, but a lot of rain. I know the OSB comes presealed, but I'd like to add another layer of protection.

I was thinking something like deck sealer or this patio paint from HD: http://www.homedepot.com/p/BEHR-Premium-1-Gal-PFC-35-Rich-Brown-Low-Lustre-Porch-and-Patio-Floor-Paint-630001/203939583

I spent $100 dollars on a thick, large tarp that lasted a couple months, but the wind destroyed it. It gets pretty windy up there. Below is a picture of the subfloor I have finished. It is about 320sqft.

I understand, I can't completely waterproof this stuff, but I want to try and at least get it through this winter season.

enter image description here

  • How is it attached? Your best bet may just be to pull it up and store it.
    – Drew
    Oct 19 '15 at 19:17
  • @Drew It is just screwed down, but I'd like to not work backwards if don't have to. If I can throw a coating on it, I'd rather do that. Removing it is certainly an option if nothing will protect it.
    – Ronnie
    Oct 19 '15 at 19:23

Prime and paint is your best option. Exterior paint will create a thin latex layer of protection over the surface. Use primer first to be sure and get a good bond with the somewhat-presealed OSB, then two coats of a quality exterior (porch paint should be great) paint. Two gallons of paint and two gallons of primer should be plenty for two coats. And remember that a coat of primer and a coat of paint is better than two coats of paint.

Be sure and and get very good coverage on the edges. I might go so far as to caulk the seams with some cheap caulking to prevent water from soaking to the cracks.

  • I was just talking to my friend about caulking the perimeter actually so rainwater doesn't run under the floor when it hits the tyvek. Ok so primer and an exterior latex paint. How well would that hold up to walking on it? I am guessing it would start to peel if too much foot traffic was on it. What about a rubberized roof coating?
    – Ronnie
    Oct 19 '15 at 19:45
  • 1
    If you plan on finishing the cabin in a year or so, just paint should be fine, and you can always put another coat on high traffic areas if it looks like its wearing down, but "porch paint" is made for that. I'd be worried that a roof coating would be too thick and may start to be a hassle when putting up walls and the finished flooring. And to be clear, I'd caulk the perimeter and all the joints - just use the basic cheap caulking.
    – JPhi1618
    Oct 19 '15 at 19:50
  • Ok great! I'll stay away from roof coating thing. From what I read it's more of a rubberized coating. I'm guessing I'll have a roof over it within a year and putting another layer on the higher traffic areas shouldn't be a problem. I will definitely do the primer first. All the joints have been caulked actually. It is just the perimeter that hasn't You can see the caulking on the joints in my photos
    – Ronnie
    Oct 19 '15 at 22:01
  • do you think a primer/paint combo would be a bad idea?
    – Ronnie
    Oct 19 '15 at 22:21
  • I'm not sure I believe in the paint primer combos yet... I'd do separate since the extra layers building up will help. I'd use a combo if going over a previously finished surface. Also, if you don't mind working with it, use an oil based primer. You can then cover with a latex paint.
    – JPhi1618
    Oct 19 '15 at 22:37

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