Buckled Wood floors

Old 09-29-05, 11:46 AM
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Buckled Wood floors


I had most of our entry level carpets replaced with oak hardwoods in Apri 05. To match existing hardwoods, the installers used un-finished wood and then sanded/stained and applied 4 polyurethane coats.
The wood was let to acclimatize for about 5 days before installation.

Several weeks ago, we noticed moderate buckling in all the newly installed areas. The floor has a wavy pattern - not smooth when walking barefoot.
The old wood areas are fine.

The installer then checked the moisture content of the wood in several areas and finds it within acceptable limits. His solution is to re-sand to remove the tops of the buckling, then re-stain and re-coat urethane.

My concern:
1. In winter (Atlanta), will there be unacceptable gaps between strips?
2. Would one expect buckling again next summer?
3. How many re-sandings are allowed for a 0.75" thick strip before it can't be re-sanded anymore?
4. What is the expected time between re-finishing for a floor that is well taken care of (no kids, no pets) ?

Thanks in advance for your advice.

Old 09-29-05, 08:52 PM
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Buckling of wood floors is usually indicative of moisture issues. If product was allowed to acclimate, expansion gap (3/4") around perimeter of room, and vapor retarder (15# minimum roofing felt) installed, usually there is not a problem. Moisture content of strip flooring and subfloor should have been tested with moisture meter and no greater than 4% difference. If installed over a crawl space, there should be an 8 mil minimum polypropylene vapor retarder over soil. If installed over a basement, basement should be dry. If installed over a concrete slab above grade, there should be a vapor retarder installed over concrete, and 3/4" plywood or OSB subfloor installed on top of vapor retarder or over 2x4" sleeper system. If buckling does not correct itself with a dehumidfier, sanding an refinishing is an option, if all moisture issues have been addressed. Temperature should be maintained year round at around 70 degrees and humidity levels at 35-55%.

Gap should be minimal if hardwood flooring was installed as indicated and temperature and humidity maintained year round. If moisture issues are not addressed, buckling can recur. The number of sandings of solid hardwood depends upon the amount of wood removed when sanded. Typically flooring does not require resanding if wood is in good condition, if you do not want to add or remove stain, and only finish is required. Surface finish is then screened to provide tooth and new finish applied to surface.

Grit is the major enemy to wood floor finishes. Grit gets tracked in on shoes. When you walk on grit, it is like sanding your floors. The Japanese can go 200 years or more without refinishing floors because they do not wear shoes indoors. How well you maintain floor in high traffic areas to keep it grit free, is the secret to the longevity of floor finish.
Old 09-29-05, 09:20 PM
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I'm pretty sure your getting what we call cupping confused with buckling. You would not be able to sand a buckled floor as the boards would not be on the floor! they would be raised up off the floor in a tenting fashion, instead of each individual board having a cup effect.

I bet money, there is no moisture barrier installed in the crawl space under the home, and the subfloor is considerablely wetter then the wood that was placed on it. The bottom of your flooring is wetter then the top of the flooring!!!

If it is sanded in it's cupped state, it will be the opposite and crowned when the moisture leaves the boards. Instead of high edges, it would have high middles of each board.

The subfloor was not withing 4% of the acclimated flooring.
Some guys have a moisture meter, but fake that they know what they are looking at, when they use it, like smoke and mirrors from the magician.

Ask to see his moisture chart that he uses to compare readings, with his hygrometer, and I bet he looks at you real funny, like a deer caught in the headlights.
Old 09-30-05, 10:26 AM
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Thanks for your informative replies.

You are right, the floor are cupped, not buckled.
The wood floors are above a basement - there are HVAC vents in the finished section and a de-humidifier in the unfinished section.

The moisture meter that was used had ranges with LED's - green, yellow and red. Several readings were taken and all were in the green lights - which the installer said means that the moisture content of the wood strips were within limits.

From what I can recall, felt was laid down between the plywood subfloor and the wood strips.

Your suggestions are to first dry out the subfloor before anything else by running the dehumifier continuously in the unfinished part of the basement. If this does not solve the cupping - even the resanding would not work as I would get crowning in winter?
I am a little confused on what I should do next.

Apart from the above, would you suggest installing a central dehumidifier to control humidity in the summer months?

Old 09-30-05, 11:01 AM
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I've had a similar problem in just a small section of my floor. 3/4oak, professionally installed 4 years ago. My salt water tank overflowed about 8 months ago.... While we got up most of the liquid before damage occured....I notice minor cupping in a relatively small area around the tanka few weeks later. It's been that way for 8 months... seasons and humidity notwithstanding(very dry climate here). As it's not a serious issue (out of the way area)... I'm leaving it as is.... for now... At some point, however, I'm going to have to smooth it out... and, as it's been such a long time with no changes... I'm thinking/hoping.... crowning won't be an issue...

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