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Gaps from contractions in new wood floor

Streamline | Posted in Construction Techniques on February 28, 2009 06:38am

My floor was installed in April ’08 with 7 1/2″ wide plank engineered Moabi (like brazilian cherry) wood.  The flooring material was acclamated for 2 weeks in the house before installation over radiant floors.  I have left the heat on at 69 degrees and never change it as I am aware of, and sensitive to, the effect of temperature fluctuation to wood floors. 

This winter, I notice a number of the boards are separating length-wise. The gap can be a small crack opening between the boards, up to 1/32″.  About 1 out of 20 boards separates.  I have a wood repair epoxy gun designed for repairing floor separation (wood to floor, not wood to wood).  I am wondering if I should drill a tiny hole and squirt some in to the space between the planks (the separation).  What’s the consequence of doing this, versus doing nothing?  What other solutions are there for this?  This bothers me because I do not want water to spill in the cracks and cause damage to the flooring, not to mention it feels really bad when walking on the crack as socks snag on to the edges of the boards.

I would appreciately anyone having experience with this type of problem providing some advice.

 

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  1. davidmeiland | Feb 28, 2009 07:09am | #1

    I wouldn't do anything. It's drier in the winter, and wood shrinks a little bit. It may very well expand again when there's more moisture in the air, closing the gaps. There is very little chance that a wide-board floor like yours is going to look pristine year round. I would expect some cupping, some gaps, etc.

    1. Streamline | Mar 01, 2009 12:01am | #3

      What about those homes with oak wood floors that are 10 years old without any cracks in them? There are plenty of homes that have pristine tight floors 10+ years old. Albeit they are 2" wide strips. I would think that engineered floors would be even better. Is it a function of wide plank?? I was certain that engineered floors solved that. I have a humidifier integrated in the HVAC system. Are you aware of any flexible filler products we can squeeze or trowel in the spaces?

      Edited 2/28/2009 4:04 pm by Streamline

      1. Piffin | Mar 01, 2009 12:21am | #4

        Butcher's wax 

         

        Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

      2. davidmeiland | Mar 01, 2009 12:23am | #5

        There's a big difference between 2-1/4" flooring and 7-1/2". I haven't used the species the OP mentioned, and he didn't say what the MC was when installed, etc. etc. I would not put any filler in given his circumstances. He hasn't even been thru a complete year. He could have seasonal gapping there or it could be permanent if the floor was installed too wet. If you are running humidity control and keep your house consistent all year around, you should see few if any problem assuming the installation circumstances were correct in the first place.

        edit--sorry, you ARE the OP. FWIW, temp variation makes very little difference in wood movement, it's mostly about humidity.

        Edited 2/28/2009 4:24 pm by davidmeiland

      3. User avater
        mmoogie | Mar 01, 2009 12:42am | #6

        >>Albeit they are 2" wide strips.>>Aye, there's the rub. Those 2" wide solid wood flooring strips are actually probably shrinking more as a percentage of their width than your engineered flooring is. But 1 percent of 2" is going to be less absolute shrinkage than 1 percent of 7.5 inches.Even then, you are comparing apples to oranges. Would shrinks almost exclusively tangentially to the grain, ie: widthwise. On solid wood floors you will probably never see any shrinkage lengthwise. With an engineered floor, the substrate of the flooring is a chipped-wood substance with grain going every which way, so you probably see quite a bit more shrinkage lengthwise that you would a solid wood floor. By the same token, you see very little widthwise.I would leave it alone. It'll close up again in the summer. and open up again in the winter, and close up again in the summer, and...Unless you implement some form of humidity control in the house.Steve

      4. dejure | Mar 03, 2009 09:46am | #9

        Re "old houses have nice tight wood floors": They don't have radiant heat under them.

        Edited 3/3/2009 1:52 am ET by dejure

        1. davidmeiland | Mar 03, 2009 05:17pm | #12

          Changes in temperature cause very little in the way of wood movement.

          1. dejure | Mar 04, 2009 03:18am | #13

            A little goes a long way, as they say (e.g., 1/64" x 32 (boards)= 1/2"). Now, through a grand piano on a floating floor and you might be safe presuming it's been, for all purposes, locked to the sub floor.There are a number of campers out there who are experiencing new technology (radiant heat under wood floors) who, it is indicated, would be hard pressed to believe wood is not affected by heat. This is stated to occur on a daily basis, so it's not likely to be a moisture issue. Their floors are popping loud enough to wake children from sleep.Since the "experts" on the matter are still figuring this more and more common phenomenon out, we all, certainly, use some insight as to what other possibilities exist to cause these problems.

          2. fingersandtoes | Mar 04, 2009 03:35am | #14

            "A little goes a long way, as they say (e.g., 1/64" x 32 (boards)= 1/2"). "

            But the thing about wood movement in floors (and for that matter house framing) is that it is centered around the fixed point where each wood member is attached. So that while you can do the math adding 1/64ths by the boards until you come up with an alarming number, you never experience any gap larger than 1/64th.

            I take your point about heat and wood. My living room wall pops every time we have a sunny afternoon.

          3. dejure | Mar 04, 2009 04:31am | #15

            Those with floating floors, under which may be found a radiant heat source, shouldn't have movement issues. Or at least it would seem to be the case. But that why I "threw in" the grand piano. A dresser full of this and that should have some effect, as should a fridge and so forth, as "the fixed point where wood is attached," for these purposes.All that aside, what amount of movement in wood, I wonder, must there be before it gets noisy? I know frozen apple trees and other fruit trees do a good imitation of a 30-06 going off, when frozen. But that's a different orange/apple.That which I least want to do is oft that which I most should do. And I can't afford cheap.

  2. FCOH | Feb 28, 2009 07:21am | #2

    Not sure I would fill the gaps with anything as they will probably squeeze out whatever you put in once the summer comes around, or worse buckle.

    When I put my radiant floor in I was told not to use boards more than 3 1/2" wide. I wanted to test this theory so I put down 4 1/2" wide boards. To my dismay they were right, although mine separate width wide and I agree it's not the most comfortabe to slide around on. Most people wouldn't notice though.

    One thing I would look into is the humidity level inside your house. Big swings from summer to winter could cause this. Keeping your indoors between 30-50% relative humidity is ideal. But consistency is key as that will reduce the swelling/shrinking.

    Not sure about you but I have no way of controlling the humidity in my house other than a plug in humidifier/dehumidifier(which I don't use). Ideally I would like to keep the interior at around 40-45% as my boards are tight together then. But right now w my house at 32% I have gaps as big as 1/16".

    I don't know what air control system would work for your situation but you could always post in the heating/cooling threads and probably find out.

  3. fingersandtoes | Mar 01, 2009 01:44am | #7

    You really aren't going to know what is happening until next summer when it either expands and fills the voids - in which case you probably don't want to have put anything in that would impede the movement, or the cracks stay open meaning it was installed too wet and you are safe to use some fill material.

    It must have been a bit of a shock when they opened up. I, like you, assume engineered wood is very stable.

    1. Streamline | Mar 03, 2009 05:13am | #8

      OK guys.  Looks like the "leave it alone" have it.  The shrinkage is actually width-wise, not length at all.  Because of the plywood's cross grain gluing, they claimed high stability over solid wood.  Anyway, it gapped so my only option is to wait, though Piffin's butcher filler is mighty appealing.  I will leave it open at least 1 year to see what the cycle is before taking actions.  Thanks guys.

      1. User avater
        Matt | Mar 03, 2009 02:25pm | #10

        Even though the substraight of the engineered boards is more stable than solid wood, you still have a solid wood walking surface that expands and contracts.  One of the caveats of wide board flooring is more expansion and contraction based on a % of the width.  If a few 2.25" wide boards shrinks 2% that is ~4 hundredths of an inch.  If a 7" wide board shrinks 2% that is 14 hundredths or around 3 times as much or around 1/8th"!  OK - so your engineered floor shrinks only shrinks/expands 1% so be happy!   Wide board flooring has a certain "romance" about it but fact is that 200 years ago when it was in very common use, the floors were rather "rustic" - they didn't look like a mirror.  My flooring guys won't guarantee any wood flooring with a width over 4".    You probably should have been warned, or maybe you were...

        I think part of the problem is that you are looking too close.  For example, I recently built a home for a woman.  She toured several spec homes prior to purchasing the home from us and seemed happy with what she saw.  When she got her new home and put on her reading glasses and checked out the walls and woodwork from a 6" distance she was unhappy, yet she had looked at the same quality homes a number of times while she was picking out her interior finishes. 

        I know you aren't down on your hands and knees checking out your wood floor, but you gotta realize wood is a natural product.  It is not gonna be entirely uniform.  If you take a closer look at other people's wood floors I think you will see little issues with those too.  Also, I'm guessing that the radiant heat isn't helping as it applies the heat right to the wood.

        BTW - is this glue down, nail down, floating, or what? And, what is under it?   Just curious.

        Also btw - we have 2.25" solid oak flooring in our house.  We do have some seasonal gapping.  How much?  Not sure, I'd have to get down on my hands and knees...

  4. frenchy | Mar 03, 2009 05:01pm | #11

    NO! absolutely not!

     

     do nothing!

     

     wood will shrink in the winter and swell in the humdity of the summer.. it's the nature of wood!

       If you jam something in there now come summer it will be squeezed out and  the flooring ruined..

     Don't like small gaps?  Don't use wood, follow another trend!

     

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