Hump in laminate flooring - belt sander + shingles/felt?

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  #1  
Old 08-05-14, 10:47 AM
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Hump in laminate flooring - belt sander + shingles/felt?

To make a long story short, we put laminate flooring down this weekend, and the main beam of the house created a bit of a hump in the living room. Not sure of the exact height of the hump, but it's enough that I'm stressing about it. I've been researching it, and it sounds like planing the joist is the common answer. Instead, could I sand down the subfloor and use some shingles/felt on the low points to raise it enough where it's not so noticeable? Or will sanding the subfloor reduce the strength? It's 5/8" particle board that I'd be sanding. The laminate is 12mm thick, and is running perpendicular to the joists, not parallel. Thank you for any help you can give!

Nate
 

Last edited by MN-Nate; 08-05-14 at 12:38 PM.
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Old 08-05-14, 10:49 AM
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Welcome to the forums.

Do you really have particle board under the laminate (not OSB)?
 
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Old 08-05-14, 10:55 AM
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I believe so. It chipped off the edges quite easily, and looks nothing like any OSB I've seen. Actually now that I'm looking at some pictures, it could be an MDF like material. It was also very dense, and quite difficult to screw into. It's for sure not OSB or plywood.

Oh and thanks for the welcome! I've been coming to this site for a while to read up on flooring, and it's been a huge help.
 

Last edited by MN-Nate; 08-05-14 at 11:28 AM.
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Old 08-05-14, 12:15 PM
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Lets determine how bad of a hump you have first. Take string and two people stand at opposite ends of the room, stretch the string tight and lower one end to the floor. Then slowly lower the other until it touches something. Do it from both ends and let us know if it is a hump, or if the whole floor waves.

This is actually a great time to update the subfloor by removing the particle board and installing a stiffer 3/4" T&G Advantech or similar underlayment. It may help smooth out the dip or bump you are experiencing. Particle board doesn't add any strength to the floor.

Consider installing your flooring perpendicular to the joists to help ease some of the waves. However, the flooring manufactures have guidelines with regard to amount of tolerable deflection in the floor.
 
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Old 08-05-14, 12:43 PM
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I should be able to do the string thing tonight, although I'm a bit afraid of what the results might be! I might even snap a picture or two. It would be a great time to update the subfloor if it weren't already covered in laminate Neither myself nor my wife will want take it all back up to install new subflooring. And I had to revise my initial post, because the flooring is running perpendicular already. I had to think back to how the joists ran in that room, since they switch direction after the main beam.
 
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Old 08-05-14, 02:29 PM
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One more note: the subfloor had writing on it about it containing urea formaldehyde, so at this point I'm going to assume it's MDF.
 
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Old 08-05-14, 04:29 PM
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If hind sight is 20-20 then you, my friend, have achieved perfect vision.

The easiest part of many jobs is the installation of the final covering, in your case Laminate. The painstaking and un-gradifying portion of the job is the prep work needed for the success of the final product. You skimped a little on the prep - and you either need to live with it or correct it. If you are indeed perpendicular to the "hump" then you have to peel the whole floor back regardless of how you attack the repair. OR... Install your furniture (which has weight) and see if the problem resolves itself in the short term. As long as there is not too much flex, the click lock on the laminate should be OK.
 
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Old 08-05-14, 07:52 PM
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Ha, yes, perfect vision indeed! The sad part is I had all the stuff ready to go to make the floor flat as we went, but the person working with me apparently didn't feel it was necessary. Anyway, here's a picture of the hump.

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As for parallel/perpendicular, the joists run perpendicular to the laminate up until the beam, which is what is causing the hump here. So the laminate runs parallel to the beam, if that helps. I've been trying not to walk on it for now, but there doesn't seem to be much flex at all, so it could possibly be ok. It'll just be reminder every time I walk by it that preparation is key!
 
  #9  
Old 08-06-14, 04:57 AM
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Can you get underneath the spot just to the right of the hump? Maybe you can install some cross blocking in the joist cavity that spans the gap and you can jack the floor level and nail off the blocking.
 
  #10  
Old 08-06-14, 06:42 AM
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No, not really. There is a steel beam running perpendicular to the beam causing the hump, blocking access. In the basement there is a wall covering the steel beam on one side, and the furnace on the other side. I suppose I could cut into the ceiling beneath the hump and attack it from there. Could you explain a bit about the cross blocking and what that might entail? I assume that's what I'd be jacking up to get rid of the dip, right?
 
  #11  
Old 08-19-14, 01:44 PM
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I haven't done anything with this yet, as we finally moved in and are sorting our stuff out. Is going through the downstairs ceiling the best option on this, or should I pull it all up, pull the subfloor up, plane the joist, and reassemble?

Nate
 
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