Two years ago we had wooden flooring installed. We had the wood sit out for 4 weeks to acclimatize as much as possible before we installed. About 6 months later (fall) we started to notice gaps between some of the floor planks. Since then they haven't gotten any larger or smaller with some being 1/8 of an inch. We ran humidifiers for a few weeks hoping that the humidity would help, but this didn't do anything - we are in Colorado.

I have looked around for a wood fill, but there doesnt seem to be anything like that on the market for larger areas. I recently bought some stain to stain in the gaps and try to reduce the appearance of the gaps - the floors are dark stained. But the gaps are still visible. I also just bought some dark caulk which I read helps, but wanted to get some opinions first before I start caulking the gaps.

I am hoping for a product that is easy to apply and fills the gaps - something similar to a wax type product that you can apply with a putty knife. Any ideas would be appreciated..!

4 Answers 4


If your floors are "set" meaning that the gaps are consistent through out the year I would advise the following.

  • the best thing you can do is add wood strips to your floor. So you would cut out parts of the existing planks with a circular saw (set to the depth of the wood so you dont cut other things) and notch out a few planks - dremel might help here too. Then add wood strips to fill in the blanks. Nail them down and seal them. You are fixing a poor install. The wood didn't acclimate or had way too much moisture when it was shipped. You didn't have it sitting outside right?

  • and if you don't want to go the permanent and correct route... then I would personally buy some bondo wood filler, some colorant to match your existing hardwoods, and poly. Fill your gap with the bondo to about 80-90%. Put on a second coat (next day) with colorant that is level with floor or a little higher. Sand it flat. Several coats of poly. If you use cheap wood putty you will have cracking and dry ugliness.

  • wood was inside at place of install for 4 weeks. Should have been plenty time for shrinkage, but obviously not. I like the bondo wood filler option. Will try that in small place first. Apr 22, 2013 at 15:46
  • Make sure you get colorant for it. Once it dries you don't want to have to "paint" the color on unless your wood is really dark and even then the paint could come off if poly is scratched.
    – DMoore
    Apr 22, 2013 at 15:51
  • And I would personally never do the first suggestion - I just know it is more permanent. I have seen this done and it takes a ton of time. If your cuts aren't exactly right... then you have to fill areas for the wood filler strips not filling.
    – DMoore
    Apr 22, 2013 at 15:57
  • Will the bondo crack over time? Jan 7, 2017 at 16:25

Trowelable wood filler. DuraSeal (among others) makes a "loose" filler that is almost pourable. You can use a floor squeegee or a grout float for more control. You normally dump it in a puddle and move it around, sanding it smooth just before sealing the floor. Since your floors are finished, you could use a grout bag and carefully fill each gap.

It comes in a variety of colors. If you blended several at the gap (not mixed, pushed in like an artists palette), you can get some variability and less single color. After curing, an overcoat of water based poly will help blend the whole floor together.

I would not caulk. It will stick out worse than the gaps and you cannot overcoat with poly later (after a refinishing.

  • Will this filler crack over time? Jan 7, 2017 at 16:19
  • Cracking is mostly a function of the moisture min vs max. If you can keep the swing (measured in the wood, not air RH) below +/- 10 %, you will have a good chance. Doing the repair during the middle of the swing (in most places, mid spring or mid fall) will moderate the pressure developed.
    – HerrBag
    Jan 8, 2017 at 21:58

Hi There is also a rubber tube type floor filler that will expand and contract as your floor moves in the different temperatures of the seasons http://www.draughtex.co.uk/ It is in the UK but they ship world wide.

  • 1
    Are you affiliated with this product in any way?
    – Tester101
    Mar 28, 2014 at 13:32

For god's sake don't go near that stuff (draughtex). We got a couple of rolls to try it. It looks awful, takes a ton of time to out in and it gave me nightmares about being a huge fire risk so I ripped it out quickly and then went back and filled the gaps with a mix of sawdust and rubber glue and the stain that coloured the floor. Got into quite an effective technique fairly quickly- not unlike buttercreaming a cake prior to icing- small scoops pushed in with a semi-flexible spatula at a 90 degree angle to the crack, finished with a sweep along the length of the crack to ensure everything is level.

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