I am installing my first ever hardwood floor. It's pre-finished 3/4" solid wood, and it's been pretty fun. I've noticed that some of my end joints have some very tiny gaps on one side of the joint (flush on the other side). I often have to look closely to notice, but some are visible from standing up.

My assumption is that these small gaps result when the board next to the end joint has a very slight bow to it (either concave or convex relative to the boards that comprise the end joint). I suppose it's also possible that the boards were not cut at the factory with perfectly square ends, but enough of my joints do meet perfectly that I don't think this is the case.

My question is: is there anything I can realistically do about this? It's not really a big problem and maybe the answer is just to live with it, but it's slightly irksome to the perfectionist in me. How do I ensure as I lay each row that it doesn't have any slight curve and, therefore, will not pass along any problems to the next row? Are there any tricks to this?

If I could perfectly straighten the bowed boards, it would presumably solve the problem, but frankly, I usually can't even tell if a given board is indeed bowed or not. Certainly not by eye, and not with a 4' straightedge for the shorter pieces. Some of the longer pieces appear to have a very slight bow relative to my 4' level. And even if I did know a board was slightly bowed before I installed it into the floor, I'm not sure how to install it perfectly enough that such slight discrepancies are avoided...?

Here is a photo of the floor - it was put down from right to left (tongues facing left of photo).

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Here is close up of end joint from the middle of the photo. board width is 4 1/4". My guess is the light-colored board to the right of the end joint is slightly concave relative to the end joint. enter image description here


3 Answers 3


I'd use wax filler or even colored caulk (sometimes sold as wood mastic) -- a tiny amount. Let a bit of it dry first and compare the color to the wood--it can change substantially as it dries/hardens. Some laminate flooring I bought last summer (made by Classen) came with a wax sealer pre-applied.

For a solid (or even multi-ply) wood, sanding is sometimes an option, but for a beveled (v-groove) edges like yours it will probably look a little odd anyway and it's more labor intensive, but you can reshape the bevels this way. This requires pulling out the pieces though. If you really wanna go this way use a fine grit, 180-220 at least and an orbital sander. Try your technique on a piece of scrap first. You'd have to apply varnish after that and chances are it won't look exactly the same as the factory applied one. So I'd leave this route for when you redo your whole floor.


Looks good! I don't think it gets much better than that with most prefinished flooring.


Sometimes you can have cases where there will be a little saw dust, dirt, etc. that gets trapped in the groove of your boards, and sometimes there can be small shards of wood hanging off of the tongue of your male boards. Both of these can hold you off from getting a perfect fit. It would be a good idea just to check them real quick before you install them. As for the gaps that are already in your floor, wood filler is a good way to go. Just get some to match the wood that your flooring is made from, scoop it out with your finger, rub it into the space, and wipe the excess off with a rag. It would also be a good idea to check periodically and make sure your floor is staying square, because this can sometimes cause tiny cracks too.

  • any suggestion what to do if I determine floor isn't quite staying square? In one room I'm doing I have had an issue where one of the pieces a while back must have had the slightest of curves to it. I've been using a flooring jack to squeeze subsequent pieces so that any tiny cracks between pieces are pretty much eliminated, but this has the side effect of continuing the slight curve, which then results in the problem I originally described of tiny cracks at end joints. I'll update my question to clarify this additional question. Commented Nov 17, 2017 at 2:55
  • Typically there are two main reasons why flooring isn't staying square with the walls. The first is that the first run of your flooring was not started square, and the second is that sometimes there can be a tendency to push one end of your boards a little tighter against the other ends, which can also lead to problems. If your floor isn't very far off, say 1/4" to 1/2", or even a little bit more, you can usually just rip the boards in your last run to match the wall they are going against. Commented Nov 18, 2017 at 1:41
  • Another method is to find out which side of your flooring is getting to the wall faster, and try to push the boards tighter against each other, and on the other end push them together more gently. Stop periodically to measure from your wall to your flooring to check your progress. It usually will take quite a few runs to get your flooring back square with your walls. Commented Nov 18, 2017 at 1:43

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