Hardwood Floors in a Humid Climate: What's normal?
June 20, 2018 8:42 AM Subscribe
I had solid (not engineered) 4" plank hardwood floors installed in my house about a month ago. It is verrrry hot and humid where I live right now (97 degrees F, heat index well over 100). A couple of days ago I noticed that in one part of the house, mainly a 15 year old sun room addition, there is very slight cupping. The floor feels flat and looks flat for the most part, but in the right light you can see the edges of the boards are slightly raised. When you place a ruler along the floor it confirms this - like 1mm of cupping. The rest of the house is perfectly flat.
We have central air conditioning that works well, and our crawlspace has an expensive dehumidifier and a properly installed vapor barrier. We've had a lot of work done in crawlspace over the past six weeks so I know there are no water problems in there. The wood did sit in the house for a good 10 days before it was installed, and the company that did the work is well-respected and professional.
My question is: If this doesn't get worse, is it a problem that the edges of the boards are very slightly swelled, or is this normal? I'm reading lots of stuff online about how it's routine for hardwood floors to swell in humid summers and shrink in dry winters, but I'm also seeing all these horror stories of people trying to fix their cupped floors. Is this something I need to keep worrying about?
We have central air conditioning that works well, and our crawlspace has an expensive dehumidifier and a properly installed vapor barrier. We've had a lot of work done in crawlspace over the past six weeks so I know there are no water problems in there. The wood did sit in the house for a good 10 days before it was installed, and the company that did the work is well-respected and professional.
My question is: If this doesn't get worse, is it a problem that the edges of the boards are very slightly swelled, or is this normal? I'm reading lots of stuff online about how it's routine for hardwood floors to swell in humid summers and shrink in dry winters, but I'm also seeing all these horror stories of people trying to fix their cupped floors. Is this something I need to keep worrying about?
Best answer: I presume the sun room addition was not built over the original foundation, and if that's the case it might pay to look at the foundation extension under the sunroom, and especially at where that joins the original foundation to make sure no water is somehow seeping in down there.
posted by jamjam at 1:16 PM on June 20, 2018 [1 favorite]
posted by jamjam at 1:16 PM on June 20, 2018 [1 favorite]
Best answer: It's wood. Wood breaths, and it expands/contracts. Cupping is normal, it may be something that reverses with the seasons/humidity, it may just have been as a result of being too green when laid.
posted by GeeEmm at 3:23 PM on June 20, 2018
posted by GeeEmm at 3:23 PM on June 20, 2018
Best answer: Cupping can be caused by uneven drying, and given that you've said that this is a sunroom, that seems likely to me. The warm top just dries out faster, and that makes the wood bend toward the surface that's shrinking.
Applying an oil based finish (like tung or linseed) to the floor will tend to unshrink the top a tiny bit and also slow down the drying rate. Unlike a urethane finish it will also leave the floor able to breathe, so if it does get a little humid underneath it's less likely to cup so much in response.
I'd recommend just keeping an eye on it for a year. Most likely thing is that it will cup to some small extent and then get no worse; in some parts of the year it might even uncup again.
posted by flabdablet at 1:55 AM on June 21, 2018
Applying an oil based finish (like tung or linseed) to the floor will tend to unshrink the top a tiny bit and also slow down the drying rate. Unlike a urethane finish it will also leave the floor able to breathe, so if it does get a little humid underneath it's less likely to cup so much in response.
I'd recommend just keeping an eye on it for a year. Most likely thing is that it will cup to some small extent and then get no worse; in some parts of the year it might even uncup again.
posted by flabdablet at 1:55 AM on June 21, 2018
Best answer: Give it time. If you’ve ruled out moisture, this will settle out in time.
Installed 2” quarter sawn white oak floors and for the first 6-12 months noticed seasonal joint expansions and slight changes. 3 years later it’s completely settled down and I don’t notice and changes between seasons.
posted by donguanella at 4:47 AM on June 23, 2018
Installed 2” quarter sawn white oak floors and for the first 6-12 months noticed seasonal joint expansions and slight changes. 3 years later it’s completely settled down and I don’t notice and changes between seasons.
posted by donguanella at 4:47 AM on June 23, 2018
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posted by DrAstroZoom at 11:24 AM on June 20, 2018