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What fasteners should I use to replace the pressed cardboard underlayment with plywood for a temporary fix before installing laminate or tile flooring in the future?

Asked by Giuseppina Mercier
7 months ago
Last Updated: May 8, 2024

Hey, I have a question for you guys. So, I’m a carpenter, but I don’t have a ton of experience working on residential projects. My girlfriend’s toilet broke and it caused some water damage to the floor. The underlayment got all bubbled up and warped. It turns out that the previous installer used that old-school pressed cardboard wall paneling from the ’60s as the underlayment, and then put stick-on vinyl tiles over it. It’s all on what I think is an osb floor. The panel they used is 1/4″ thick, so my plan is to replace it with smooth sanded 1/4″ plywood. Here’s my question: for this temporary fix, would you recommend using fasteners like brads or construction adhesive? I’m thinking of going with fasteners because we might go with laminate or tile flooring in the future, and the whole underlayment would need to come up to accommodate the thickness of the tile. Any thoughts? Thanks in advance.

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Yasemin Çapanoğlu

I recently used a crown stapler and adhesive for the 1/4 underlayment.

Maja Jørgensen

I think if I go light on the adhesive, I should be able to rip out later without too many issues and just sand off the excess as well. Thanks!

Yolanda Garica

Avoid adhesive and opt for 1 1/2″-2″ construction screws instead, as using adhesive is not recommended.

Maja Jørgensen

And stuff, do they just fill the heads with mud or something? My plan was to use the stick-on tile that matches the rest of the bathroom until I rip it out and replace the entire floor.

Maja Jørgensen

I don’t believe long screws are necessary. I’m only penetrating 1/4 of the way into 3/4.

Yolanda Garica

Mentions that short screws work well, but it’s a good idea to have a firm hold on the joists.

Maja Jørgensen

Is quite logical.

Renato Alvarez

The supposed wood paneling might actually be lauan underlayment that some adhesive tile brands suggest using before installation. Make sure to nail it in every 4 inches. Is the area under the removed material dry? If there’s trapped moisture that can’t dry out, it could result in mold issues and ultimately lead to severe health issues. Mold exposure can even cause Parkinson’s and MS.

Daniel Johansen

When dealing with osb flooring, consider replacing it with half inch concrete board for tiling instead of wasting time and money.

Maja Jørgensen

I will definitely look into that before I finalize the remodel. For now, some temporary solution needs to be applied until there’s enough money to do the floor the way we want. You’re probably right about the OSB flexing and causing tile and grout to crack.

Daniel Johansen

You know what, just go for it. The money will come eventually. Just make sure not to rush things and end up wasting a lot of money and time. What if it’s been sitting with only concrete board as the floor for a month? So what if only half of it is tiled for a month? You catch my drift.

Slavoljub Branković

Well, I agree for the most part, but if the OSB is the only subfloor, it might be best to replace it with something else. Even a 1/2″ CDX would be better than nothing, especially if you want to keep the finished tile height low. You can’t just place concrete board directly on the floor joists.

Daniel Johansen

Absolutely, there’s no way the subfloor is made of OSB. If it is, then the whole house is basically garbage.

Slavoljub Branković

Oh yeah, I totally get what you mean! 😂 When I was working in Kansas City, I had to renovate houses from the 70’s with really thin subfloor made of some strange particle board that was only 5/8″ thick. It wasn’t even proper OSB or 3/4″ T&G plywood.

Iva Đokanović

Null

Hilário Mendes

Are you disposing of all underlayment that got wet?

Sue Gibson

After ensuring the subfloor is flat and stable with no flexing, proceed to install HardieBacker 0.25 in. x 3 ft. x 5 ft. Cement Backerboard on top.

Milica Santrač

For 1/4″ underlayment, stick to 1/4″ wide staples as they are the standard choice for being fast, inexpensive, and efficient.

Maja Jørgensen

Yeah, I believe what was there was just sitting there. That sounds right and it should be simple to rip out when the time comes. Thanks.

Janik Greijdanus

Opt for subfloor screws instead.

Edir Nogueira

Make sure to use plenty of 18 gauge staples when securing the underlayment, avoid gluing it down.

Umut Nalbantoğlu

One issue you may encounter is that the subfloor material you mentioned could become swollen, creating a raised area that may crumble if you attempt to sand it down to match the rest of the floor. Removing it immediately will prepare it for any future work and allow you to assess if there is additional damage underneath.

Maja Jørgensen

Yeah, I was thinking I should watch out for that. Even if it *was* swollen, I wouldn’t have tried to sand it down. I might not be an expert in residential work, but that sounds a bit like a temporary fix. This is just to get a toilet back in there. I assisted her in renting a Porta John, but it’s too early in our relationship for me to spend a lot on fixing her house. However, I can definitely help ensure she has indoor plumbing until she can afford a more permanent solution.

Umut Nalbantoğlu

I’m only going by what you’ve described, but I don’t see why you can’t just install a toilet, even if it’s on a 1/4 sheet of plywood. Maybe a picture would make it clearer.

Logan Muller

I recommend removing it all now and replacing it with 3/4 plywood!

Maja Jørgensen

Eventually the actual floor may need to be replaced, but I haven’t started on it yet, so not sure tbh. The main aim here is to ensure she has functional indoor plumbing quickly and affordably for now. I get it, spending money on a half sheet of 1/4″ plywood just to discard it in 6-24 months seems wasteful, but it’s around $30. Replacing the entire floor with a long-term solution is beyond her budget and more than I’m willing to invest at this point in our relationship. But making sure she has indoor plumbing? Yeah, I’d do that even for someone I’m not that fond of.

Kaya Evliyaoğlu

The material used for the board is called luan and typically secured in place using a 1\4 crown pneumatic staple gun.

پرهام نجاتی

Use Crown Staples

Louis Bourgeois

Remove the old carefully. Secure the plywood/luan underlayment with screws instead of adhesive for easier removal in the future. Avoid using laminate in the bathroom as it may warp and curl, even the waterproof type. Consider using LVP with the existing underlayment, or replace it with 1/2” cement board for tile installation. ✌🏼💪🏼

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