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cupped hardwoods


CheckItOut
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In inspected a home today that had fairly wide hardwoods (maybe 4") and they were slightly cupped. I attempted to measure how deep the cup was and figured about 1/32". This seems minor but I don't know if it will get worse or if a moisture barrier was installed under them. We've had a very dry (drought) summer but still have humidity as usual in NC. Should this go on the summary or just the body of the report?

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Originally posted by CheckItOut

In inspected a home today that had fairly wide hardwoods (maybe 4") and they were slightly cupped. I attempted to measure how deep the cup was and figured about 1/32". This seems minor but I don't know if it will get worse or if a moisture barrier was installed under them. We've had a very dry (drought) summer but still have humidity as usual in NC. Should this go on the summary or just the body of the report?

A board cups when its bottom is wetter than its top.

Was this floor over a crawlspace and was the crawlspace wet?

Where you put the recommendation is up to you.

- Jim Katen

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Like Jim said, more moisture below. I would be fairly concerned if they were installed on a concrete slab. either way it may indicate improper installation with no vapor barrier (I am assuming you meant to say no moisture barrier under them).

If there was a crawl space, was there a subfloor? Sometimes I see 1x hardwood installed without subflooring, not a good idea.

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Originally posted by Jim Katen

Originally posted by CheckItOut

In inspected a home today that had fairly wide hardwoods (maybe 4") and they were slightly cupped. I attempted to measure how deep the cup was and figured about 1/32". This seems minor but I don't know if it will get worse or if a moisture barrier was installed under them. We've had a very dry (drought) summer but still have humidity as usual in NC. Should this go on the summary or just the body of the report?

A board cups when its bottom is wetter than its top.

Was this floor over a crawlspace and was the crawlspace wet?

Where you put the recommendation is up to you.

- Jim Katen

The crawl space was fairly dry with damp soil around the perimeter in a few spots. Slight efflorescence in a few areas. Flat lot with no gutters and two covered porches with wooden floors that were open to the crawl space - more moisture. Insulation was fine but the house is only a few years old and we've had an extremely dry year.

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FWIW,

The NAHB performance guideline for cupping in hardwood floors is 1/16" or less over a span of not more than 3 inches. We might not think much of it and consider it too much, but there it is. The cupping might change depending on seasonal changes in temps and humidity.

OT - OF!!!

M.

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Originally posted by hausdok

FWIW,

The NAHB performance guideline for cupping in hardwood floors is 1/16" or less over a span of not more than 3 inches. We might not think much of it and consider it too much, but there it is. The cupping might change depending on seasonal changes in temps and humidity.

OT - OF!!!

M.

Thanks. 1/16" is a lot IMO...

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Originally posted by SonOfSwamp

Experience tells me that the floors ain't gonna uncup.

I bring this up because a fair number of floor guys make up some BS about how the floors will "settle down." Like the roofers say shingles will do...

WJ

If the cupping is from a recent spill such as a sink over-flow, and not due to a continuous moisture source, they will lay back down once dry (and that could take months). Saw this all too often in new construction. Trade would spill something, or a window was left open during rainfall, and the super would have the resulting water-damaged, cupped boards sanded smooth to "fix" the cupping. Afterwards, when dry, instead of the boards going back to flat, the boards would *crown*.

I ran a builder's cust serv dept for years, and I had many such crowned floors replaced as a warranty item, usually two or three months after they were sanded-smooth.

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Originally posted by chicago

If it is new construction I've heard that this can occur when they do not let it adjust to the environment before installing.

In other words wait several days.

Anyone know about this?

The wood has to acclimate itself to the moisture/humidity levels in the house. Too wet and installed, the wood will shrink and large gaps form in between the boards (most common in new const). Too dry & installed, they'll swell and cup (rare in my experience).

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Hi,

I had it on new construction in August. It was less than 1/16" but, to me, the floor looked like a washboard and I wrote it up. The builder brought back the flooring guy, who admitted that the cupping was excessive and both the builder and the flooring guy admitted that they didn't bring the wood into the home, sticker it, and wait several weeks to allow it to achieve equilibrium with the home's environment before it was installed. The flooring guy has promised that if it hasn't improved to the homeowner's satisfaction within a few months he'll come back, sand the floors flat and then refinish them.

Before writing it it up, I'd telephoned the Wood Flooring Manufacturer's Assiation (http://www.nofma.org) and had spoken with their technical experts about the issue. They'd recommended that the homeowner wait a while before attempting to have the floors sanded and refinished, because they'd felt it was going to take a while for the home to lose all of that excess moisture and for the floors to finally reach equilibrium before they could be successfully re-sanded and refinished.

Click here for a link to the question on their FAQ page.

ONE TEAM - ONE FIGHT!!!

Mike

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