Wide plank wood floor installation and humidity %

laurajane02April 28, 2013

Hi GWers,

I have a question about our wood floor. We are installing a pre-finished 8" wide plank white oak floor. The installation is scheduled to start tomorrow. The wood has been sitting in our house for about 5 weeks now and our HVAC has been running for 3-4 weeks.

However, the humidifier is not hooked up. We have been monitoring the humidity in our house, and it is usually around 35% (it has gone above 40%). Our wood floor supplier requires a relative humidity of 40-50%.

We live in a very dry climate in Southern BC.

Should we ask the flooring installer to wait a week while we increase the humidity in our house? Will a 5% increase in humidity cause cupping? I'm going to ask our installer tomorrow but I thought I'd check here first.

BTW, I would have been more on top of this, but we just had a new baby.

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You might want to ask your question of the manufacturer. Where in the house did you measure the humidity? The ideal place is in the area the wood is stored since humidity levels can vary in different parts of a new house. Also it would be better if the wood was not stored near a recently poured slab. I would want my flooring stored off the floor and each layer separated so air can get to all the wood. If it is stored in a solid pile there is no way the center can acclimate.
Since relative humidity varies with temperature, the manufacturer should have recommended a temperature range too.

This post was edited by -henry on Sun, Apr 28, 13 at 17:58

    Bookmark   April 28, 2013 at 5:19PM
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Yes from that picture it is exactly the wrong way to "acclimate" the flooring.

    Bookmark   April 28, 2013 at 5:37PM
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Thanks for replying. The flooring is stored in a few places around the house, depending on where it is to be installed. All of it is stored on plywood, not concrete. Good point about airing it out - if we wait a week, I'll ask them to do this.

I've just been looking at our touchscreen thermostat to get the humidity levels.

I know this floor is going to move to some degree - I just want to avoid any major mistakes.

    Bookmark   April 28, 2013 at 5:57PM
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Millworkman ~ Thanks for pointing that out. The wood has been sitting like this since mid-March. Should I have them lay it out properly and postpone the installation by another 1-2 weeks?

The temperature in the house has been around 19-20oC and kept constant.

    Bookmark   April 28, 2013 at 9:26PM
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I certainly would as the wider the flooring the more it will expand and contract and the worse it will look if not correctly acclimated.

    Bookmark   April 28, 2013 at 9:45PM
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Spread it out.

Out of the packaging.

One board thick in the rooms it is intended for.

It takes a long time for humidity to penetrate a pile of boards.

See chapter 3. (sorry, the site used to have chapter by chapter links, but they are gone).
Cupping is only one of the tings that can happen.

Plain expansion and shrinkage occur, even if the wood holds it shape.

See figure 3-3.

8 inch wood is going to have some decent size gaps between heating and cooling season.

And if you really are in a low RH area, it is going to continue shrinking.

Here is a link that might be useful: 'Wood Handbook'

This post was edited by brickeyee on Mon, Apr 29, 13 at 14:24

    Bookmark   April 29, 2013 at 2:23PM
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Thanks for the advice. I do know that I will see gaps in this floor with the changing seasons.

The installer came by today. The wood is now spread out. He measured the humidity of the wood in the middle of the pile and it is 7.8%. The subfloor (plywood) is currently 7.3% RH.

The humidifier is now hooked up, and we are expected to remain around 40% RH.

So, the conditions are improving. How long would you recommend we wait before starting installation?

    Bookmark   April 29, 2013 at 3:28PM
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