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I was out of town for 5 days and during that time my kitchen faucet spontaneously developed a slow leak. Upon returning home there was a 7 foot by 7 foot puddle of water in the kitchen -- probably sat there for at least a few days. Some of that water also went underneath cabinets. The kitchen has oak hardwood floors (solid oak, non-engineered, narrow 2" tongue and groove planks). Some of the planks have begun to "cup" (curl upward along the edges).

I've read that it's possible the wood may lay flat again if it's thoroughly dried out. I've also read that mold is a risk if it's not dried out properly.

Here's what I'm currently doing to dry out the floor:

  • Closed off the kitchen and raised the temperature to ~83 degrees Fahrenheit using an oscillating space heater.
  • Oscillating fans blowing across the surface of the floor.
  • Oscillating fans in the unfinished basement blowing air at the subfloor.
  • Dehumidifier running non-stop in the kitchen (30% humidity, as low as it will go).

I've been taking moisture readings with a pinless sensor, but the drying doesn't seem to be making much progress. The surface obviously feels bone dry to the touch, but on the seams where the oak planks come together the moisture sensor gives an off-the-chart reading (over 30% moisture content).

Does anyone have any other ideas for drying out the floor quickly?

I did stumble across this "rescue mat" system: https://www.jondon.com/dri-eaz-rescue-mat-system.html which appears to suck water from the floor, but the accompanying Dri-Eaz vacuum costs over $2000 (!!!). Perhaps I could connect those rescue mats to a regular shop vac and get the same effect?

Any tips much appreciated! Would love to hear if someone has managed to salvage "cupped" wood floors without having to sand and refinish them.

UPDATE: It's been one month since I posted this and I have had the oscillating space heater, fans and a dehumidifier running non-stop the entire time -- maintaining 84 degrees in the kitchen. The moisture content of the wood has come way down, but it's still elevated -- 9.3% in some spots. The cupping has flattened out a lot and I have a feeling it will completely disappear given another month or two.

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  • Talk to your better side and borrow the iron (for ironing)
    – Traveler
    Commented Feb 2, 2023 at 1:11
  • Are you really suggesting the OP "iron" his floor?
    – RMDman
    Commented Feb 2, 2023 at 1:26
  • Were the planks prefinished before installation or was the floor finished in place? If there is cupping then it might be a benefit to go over the seams with the shop vac, maybe the crevice tool or maybe the water removal tool or maybe just the floor tool. Commented Feb 2, 2023 at 4:21
  • I don't think you have to worry too much about mold, even if you get some in some seems or whatever, it won't grow and spread like it does in persistently wet environments.
    – dandavis
    Commented Feb 2, 2023 at 5:20

2 Answers 2

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I believe you are going about the right way. Even when drying lumber using dehumidification techniques, it will take a least a week to get the moisture to start going down, 2 weeks to get a stack of trim at 20% MC down to a usable dryness. I done this before with cedar that came in too wet to install built a "dehumidifier room" and set 2 dehumidifiers running 2 weeks straight, dumping the water out on arrival at work and again before leaving for the day.

Your floor, since it has a few layers laid tight together will take longer, since there is no air space between the layers to aid in drying out. It will be slow, but it will dry out eventually.

The cupping should go away over time. The surface is drying faster than the bottom of the flooring since the subfloor is keeping it from drying out at the same rate as the surface. You may already know this, but wood swells up when wet, so the bottom of the flooring is wetter than the surface, hence the cupping. Once the bottom of the flooring gets as dry as the top, it will flatten out. Be prepared for it to take months.

If you decide to sand the floor to flatten it out before it is dried out completely, you will run the chance of seeing to floor "dome" instead of cup, when it finally equalizes in MC throughout the flooring.

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  • what about the OP's idea of using a shop vac connected to a "rescue mat"? Would there be a benefit to going over the seams with a shop vac crevice tool or the water removal tool? Commented Feb 2, 2023 at 4:17
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    Sounds like a very expensive proposition. Not know anything about it other than what the company claims. I could see it drawing up water between the subfloor and finish floor, but to suck out the water that has permeated into the wood grain, seems to be asking too much for it to do IMHO. I would imagine most if not all of the water trapped is already been taken care of with the dehumidifiers. Now it is just a matter of letting nature take its course on the reversing of what water does after setting on a wood floor for possibly days.
    – Jack
    Commented Feb 2, 2023 at 4:25
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    @ElliotB This is top notch advice. Finish carpenters will often let their high-end material sit awhile to match the temperature and moisture of the job site. It sounds like you're an engineer of some sort, and you're looking to engineer a solution, but I think Jack's right that patience is the way to go. You're already raising the saturation point, circulating, and extracting, and your just constrained by permeation. Unless you want to strip the finish off the floor, turn the room into a dry sauna, or drill lots of holes, best to hold fast. Patience is cheaper than those mats you linked. :D
    – J D
    Commented Feb 2, 2023 at 16:58
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We had a refrigerator valve break, probably 4+ months ago or so, and like you, it was on top of 2" wide solid oak flooring that had been finished with several coats of polyurethane when we had the oak put down ~10 years ago. Fortunately we were not on vacation at the time, but it had been leaking for quite a few hours, based on the amount of water that had dripped and leaked down into the basement below. This was on top of plywood and paper underlayment.

We blew fans on it for a few days, and tried to make sure the humidity in the house was as low as we could get it. Had some moderate to severe cupping for probably a good month that was very visible. But then the 2nd month it started to un-cup, and now, unless we really know what to look for, there is no indication of there ever being an issue.

I might also suggest if you're really wanting to keep the humidity down that you visit a rental place (or damage mitigation company) and see what they have for heavy-duty dehumidifiers that can pull a lot more moisture out of the air than your residential dehumidifier.

Now in our basement below that area, there's still some drywall repairs to be done, but the oak floors themselves came out fine.

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