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Reasons for hardwood boards separating?

Posted by hollan (My Page) on
Sun, Feb 7, 10 at 14:01

The oak hardwood floors in our 1950's house were refinished less than a year ago. When we moved in six months ago they were smooth and looked new. Since then, some of the boards have started to separate, some as much as 1/8". Does anyone know what could cause this? It has rained a lot so I am wondering if it is from moisture or even a foundation problem. I would like to find the solution and stop it from separating further.


Follow-Up Postings:

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RE: Reasons for hardwood boards separating?

Did you do anything to change the environment in the home? For example, did you finish the basement, add insulation, change or upgrade the heating system, install new windows?

An existing wood floor usually moves when the relative humidity levels above and/or below the floor changes.


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RE: Reasons for hardwood boards separating?

It has rained a lot so I am wondering if it is from moisture or even a foundation problem.

Too much rain wouldn't make them separate unless you're running dehumidifiers and heaters all the time to keep warm and dry. It's common for wood floors to expand and contract seasonally if your house is humid in the summer and dry in the winter. Does this house have central AC now, when perhaps it didn't in the past? That would make it dry year round, and the floor boards wouldn't expand back into place in the summer. Some heating systems allow you to add moisture to the air, that might alleviate some of the shrinkage.


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RE: Reasons for hardwood boards separating?

We have oil heat and the boards are worse near the vents. So if it's dry air then it sounds like a humidifier might help? We have not made any changes in the environment, but the floors were covered with carpet before we moved in. A little water does come into the unfinished basement when it rains a lot. That hasn't changed other than it raining a lot since summer, when the year before was a drought.


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RE: Reasons for hardwood boards separating?

We have site finished oak floors that are about 7 mos old. They began separating when the weather turned cold. I'm having a humidifier installed as soon as the snow lets up enough for the heating guys to get up the street.

We also had a similar problem with our Pergo in the winter, but that only separated in two or three places.

Hopefully some additional moisture will do the trick.

Totally Confused


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RE: Reasons for hardwood boards separating?

We have been in our current house which we built new for about ten years. In the summer, our hardwood floors look airtight with no gaps, and you can hear no squeaks. In the winter, there are several gaps with a couple being quite large, and the floors squeak in several spots. We keep the house pretty warm in the winter, and I know that probably makes the gaps and squeaks even worse. We don't really worry about it as we knew going into it that hardwood floors would expand and contract.


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RE: Reasons for hardwood boards separating?

I'm so glad to know this is normal! I've never had hardwoods so I thought something was really wrong. We're going to get a humidifier and look forward to everything coming back together in the summer :)


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RE: Reasons for hardwood boards separating?

Wood changes shape and size with the ambient humidity it is exposed to.

The gaps in wood flooring normally open during heating season when the inside humidity is low, and close during coling season when the humidity is higher.

There is no practical way to stop the wood from moving.

Since the expansion is a percentage of the dimension of the piece of wood, wider planks will show more movement.

Chapter 3 in the Wood Handbook linked below discusses how wood moves, and figure 3-3 gives a view of how pieces change shape.

Here is a link that might be useful: USDA Wood Handbook, Chapter 3


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RE: Reasons for hardwood boards separating?

35-55% humidity level year round is best for solid flooring. In winter in an unhumidified house numbers under 25% often occur. The larger gaps near the vents is a sure sign the floors are just too dry.


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