My boyfriend and I are installing a glue-together floating floor over a concrete subfloor in a 3rd floor condo. The planks are engineered bamboo, about 7 feet long and 7 inches wide. The subfloor was uneven so we had a contractor level it with cement, however, we realized when laying the wood the floor was still not level. We tried to fix the problem as we went along by stuffing roof shingles and extra underlayment in low spots and it appeared to be doing the job, but after laying half of the living room we discovered that walking on the floor is like walking on a waterbed. Even after we lifted up the edge of the floor and removed all of the extra stuff it was still very uneven. So, we laid a 6 foot 2x4 on the wood and walked next to it, marking the low spots and tried to create a contour map of underlayment to fit the low spots. But when we slid that under the floor it still was extremely uneven. I think the problem is that the low spots and high spots seem randomly distributed and it's hard to fit that exact pattern -- basically the contractor did a horrible job.

So we are now considering a couple of options. I read on this forum that foam can sometimes be used to fix this problem by drilling a hole and squirting it in. Well, we can lift up the floor (not easily but it can be done) and spray foam underneath -- would that work? We're talking about a total area of about 9 by 5 feet that is problematic. Then we would lower the floor and put unopened boxes of wood on top to make sure it stays flat while the foam dries. I'm worried that it could be uneven and create bumps though. Any suggestions?

Another suggestion we heard was to try a layer of sand under the underlayment. We could lift up the floor and underlayment, try to spread the sand around and put the floor back down. That way if there were any high spots they would be more easily corrected. The worry about this method is the mess and also the possible sound it would make when walking on it. Has anyone here done anything like this?

If neither of these would work I am guessing we would have to tear up the wood in the living room (about 200 square feet so far) and then start leveling from scratch, probably with self leveling compound. If we did this, is there a solvent that would help us get the glue off and take the wood apart? Or any ideas on how to take up wood with the least amount of damage?

Thank you very much for any suggestions and advice. And if all else fails, anyone know any good and honest flooring installers in the Atlanta area who could help?

I'm sorry to hear about your floor. I'm wondering how far apart your boards are if there to close they could bridge a dip in the floor very easy. your board sould be anywhere from 1ft 6in to 2ft not sure what brand you have. It sounds like a big area thats low if stagger is good. I would wait for some more ideas before i took it apart unless it fresh glue you could lift the edge slide a 2x4 under the long side of the second row in then move the outside board up/down alittle bit then as your moveing try to pull it out. If this works/ glue still alittle wet clean with damp rag if not light hand sand later GOOD LUCK WITH YOUR FLOOR

Thank you for your response and advice! The planks are staggered with at least one or two feet between joints - some are three or more feet since the boards are so long. The dip is not exactly even, within that 5x9 area it goes up and down a bit. I was thinking that maybe since the boards are pretty flexible, that may add to the problem. They are 9/16" thick and are a thin layer of bamboo over plywood. Also, the main low area is from a crack in the cement which ran the same way as the boards so that might also explain why the boards do not bridge the dip. I guess it's more like a shallow valley with some uneven spots.

This may be a crazy idea but what about a thin memory foam mattress pad, like one inch thick? Would that hold the shape under the floor? They sell for about $60 which would be way cheaper than losing $300 worth of wood.

If its within arms reach you could cut card board strip at this point if you can't take it apart you may have to do surgery right where its at/then you may have a few options. try to lift and slide the card board under between the longside where the valley is it may help its hit or miss at this point may take couple try you might be able to make it liveable kept posting the rest of pros will be on tommrow GOOD LUCK WITH YOU FLOOR

Is it possible to lift the area of flooring up enough to be able to work on the uneven subfloor area? If you could lift it about 4 ft and get under it to do the leveling/filing with a patching compound, I think this will give you the best results. Sand used to be suggested by Kahrs many years ago but it could shift around. I know one can lift these floors up because when I first started doing these types of floors over twenty years ago, the foam had shifted out from a wall about three feet. In order to get it back in place, we lifted a wide, long section up and then braced it while moving the foam back into place. Hey, it's worth a try.

about the cardboard, is there any kind of thin but very strong cardboard that might hold up? is that better than the underlayment because it is less bendable?

Right now we are able to lift the floor up with one person on each side about a foot... enough to slide something underneath, but it would be difficult to pour a patch I think. The wood goes through a doorway and into the bedroom so it bends when we lift it rather than being able to lift it up resting on one side. We were thinking about trying a car jack, or maybe some wedges, but I'm not sure that would get it high enough either. Gary, do you remember how you braced the wood up?

thanks again for the responses!!

We put some saw horses under it.

I like Gary's idea cut at the door get a few friends tommrow to lift it lean up ageast the wall fix the floor then put a t-cap down at the door GOOD LUCK WITH YOUR FLOOR/GOOD NIGHT

I would have been calling the floor prep contractor as soon as I checked his work, BEFORE I started to install the floor.


If the panel your lifting bends in anyway, It will compromise the glued joints.

Well, we got the feeling as soon as we saw his work that this guy was not skilled. I suppose we could call him, but I think he would probably mess it up more.

Yeah, unfortunately we can't lean it against the wall since it is attached to the hallway and bedroom. The only option here would be to try to separate it at the hallway where the pieces are shorter and then we could lift the living room piece. But I don't know how to do that in a way that would minimize damage, any suggestions? I don't mind losing a few hallway pieces but I need to keep a piece with an intact tongue or groove at the end.

Does anyone think that the foam idea will work? That's still our leading contender.

what is a t-cap? Is that the same as a t-molding?

Hi, I'm looking to build a partition stud wall that will include an internal door in our garage conversion. When the garage was converted the space was split into two rooms, being a lounge and a utility room. The stud wall that separates these two rooms was created before the floating floor was installed so is sitting on the concrete garage base (on top of the dpm). The conversion was completed about 8 years ago and we are looking to separate the lounge room with a stud wall.The floating flooring is made up of the old garage concrete base covered with a dpm with celotex insulation boards and finished with 22mm chipboard floor. I am really tired now and want to rest a bit my mattress protector is looking very dirty as I think my dog does some shit over there. well,

My question is can I build the stud wall directly onto the chipboard flooring or do I need to cut out the chipboard and insulation so that I can fix the floor plate directly to the garage concrete base?

You could drill a hole through everything to get to the slab, first. Then drill into the slab and epoxy a piece of half inch all thread into the slab very 4-6 feet along the wall with a bolt within a foot of the end of the wall. A washer and nut will allow you to hold everything in place when tightened. A hammer drill with a 5/8ths inch drill will give you room to be able to add the 2 part epoxy which ought to harden within 7 hours, if you use all purpose epoxy pour into the hole before you push the bolt into the hole after.