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Subfloor Removal Method

I just moved into a home where it appears the previous owners allowed their dog urinate wherever he wanted in the family room. Upon removing the existing carpeting, I discovered OSB subfloors that have been stained black over 40% of the floor. :mad: My wife and I plan on installing new nailed/stapled down hardwood flooring. Rather than attempting to kill the odor with a pet store natural enzyme and then covering it with a shelac based paint, I would like to tear out the existing subfloor and replace it to ensure that I don't spend a couple thousand dollars on hardwood floors that end up smelling like dog urine on humid days. My plan is to tear out the existing 3/4" tongue and groove OSB that is nailed down, but after inspecting it from the basement, I discovered that is has also been glued to the floor joists. Does anyone have any suggestions for removing the existing subfloor and adhesive so that I can replace is with new OSB that will be glued and screwed down?


Re: Subfloor Removal Method

Persoanlly, I think you are being over concerned about lingering odor. First, my experience is that dog odor is not nearly as lingering as cat odor.
I have had very good results over the years using BIN shellac as a vapor/odor barrier.Due to its rouge strand like construction, I would use two coats of BIN pigmented shellac on the OSB. I would probably tape the seams with aluminum duct tape after sealing. Further, since you have access to the underside of the decking and it is inside the house envelope (rather than in a crawl space), I would seal it also. It would brighten the basement at the same time.
There are also vapor retardant barriers for under the new flooring, rather than mere rosin paper or felt paper.

Re: Subfloor Removal Method

ordjen, thanks for the response. My concern over the odor and ensuring it is gone forever is two fold. First, by scrubbing with a natural enzyme product, then sanding, and then sealing the subfloor with a product like Zinser Bin will be incredibly labor intensive and time consuming waiting for everything to dry. Second, at $34 a gallon for the natural enzyme (guessing I will need at least 2) and $40 a gallon for Zinser Bin (also guessing I will need at least 2)I'm at $150 vs. the 4-6 sheets of OSB that need to be replaced at $15 a sheet, will be less expensive and more of a quarantee in the long run. I know it seems ridiculous, but we are spending all our cash on the flooring and I am looking to minimize overall costs and quarantee the outcome. I cannot afford to rip up the floor if the smell remains when I'm finished.

Re: Subfloor Removal Method

Tear out the OSB as planned. Cut directly between the joists making 4 foot rectangles. Rock the OSB to the side, this will loosen the hold on the nails and glue. After you get the plywood out, then flatten the tops of the joists with a belt sander outfitted with some 36 grit (or lower) sandpaper, or use a plane.

This job will not be fun in the slightest. Lots of work and sweat. Let us know how it goes.

If this were my floor I'd be painting it with the Zinsser too. If you are worried about the smell coming back, paint it, wait a good long spell and sniff. I'd also be painting the rest of the room at the same time since the odor has permeated the entire space.

Re: Subfloor Removal Method

I'd recommend what Houston does, because:

1. You are very sensitive and concerned about the smell, and nothing less than replacing the old OSB will do.

2. Costs involved.

3. And what if you elected to keep the old OSB, paint it, install a new floor just to smell that old smell again?

4. At the same time, keep in mind that doing what you plan is also labor intensive, dusty and messy.

Word of caution: don't lay any new OSB unless the joists are 100% level.

Re: Subfloor Removal Method

Houston Remodeler, Thank you for the reply. I figured this was going to be labor intensive, but I want to do it right and need to do it right considering the flooring is a one shot deal due to the price. Thanks for the tips on cutting the OSB between the floor joists. Just so I'm clear, if this were your floor, you would rip out the OSB, replace with new, and then paint with Zinnser? Why the Zinnser if I am installing new OSB?

dj1, thanks for your insight. My wife and I are both very sensitive to the smell which is why I am choosing to go this route. Question for you though, you said not to "lay new OSB unless the joists are 100% level", what do you mean and why? Do you mean after the sanding? I don't understand.

Re: Subfloor Removal Method

Well here's the thing:

After you remove the glue, the nails, the wood leftovers, sand and whatever else, you take a long level (I use an 8' level) and place it across the joists. If one or more joists are too low or too high, they will throw the new floor out of level.

If a joist is too low, there are ways to "fill in" the gaps.

If a joist is too high, it must be brought down a bit, by sanding or ripping.

Your new floor will look perfect with a level subfloor.

On your question to Houston: I would let him answer that, but a coat of paint will better protect your new subfloor in future accidents and disasters.

Re: Subfloor Removal Method

Just my 2 cents, replacing 6 sheets of subfloor is a lot more labor intensive than paint. Will the paint work? I would thinks so, but urine in osb isn't a problem I've dealt with.

Re: Subfloor Removal Method

dj1, Now I understand what you are saying. Glad you mentioned ensuring everything is level after all that sanding. I didn't think of ensuring the joists were level, to be honest. I figured I would just lay the new pieces of OSB and then level as necessary, but based on your suggestion of leveling the joists, before laying the subfloor, I think I would be way better off. I know I can just sand if I am too high, but any suggestions for shims if I am too low. I was planning on using roofing shingles if the subfloor was already down, but with exposed joists what should I use?


ed21, you're probably right. Now fully understanding what I am getting into, it will be more labor intensive, but I want to do it right and am willing to spend the extra time as necessary to ensure it is right. Although, I doubt my wife is going to love all the sanding that is about to take place. :D

Re: Subfloor Removal Method

I just wanted to thank everyone on here for their advice. I was able to successfully remove the existing subfloor based on the information I received here. The removal went as planned and I was fortunate that the adhesive was much easier to remove than I expected. Thanks for the belt sander advice Houston Remodeler, with a little finese, it worked like a charm. Fortunately, the joists were level and the project went as planned. I know its one extra step, but I'm taking the advice from Houston Remodeler to paint the new floor with Zinsser BIN today. Can't wait until my new hardwood floors are in and we can start enjoying this room.

Thanks again everyone.

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