Leveling Floor

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Old 04-07-19, 01:28 PM
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Leveling Floor

Hello,

I am in the process of remodeling a living room and I am trying to figure out the best way to prep an unlevel floor for either vinyl or laminate locking planks. the lowest point on the floor is 1.5" lower than the highest point. I used a laser level to map out the depth every 4 feet. Half of the room is fairly level and then the floor slopes away after the halfway point. Underneath this floor is a crawlspace, and there is a wall splitting the crawlspace which accounts for the change in slope.

I am looking for the most economical solution to create a surface that I can install the locking planks on top of not necessarily eliminate the slope entirely. What options do I have?

Thank you,
Nick



 
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Old 04-07-19, 02:04 PM
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Floors don't have to be level, they have to be FLAT. Every floor mfg will have its own minimum requirements for how flat a floor should be. The last laminate floor I worked on required it to be within 3/16 in 10' or 1/8" in 6 ft. So while your "level" grid is great, it doesn't really translate into what it would take to make the floor flat. You don't show which walls are exterior walls, and which walls have additional rooms on the other side. Also doors and doorways may factor into the answer, and none are shown.

The only answer I can give based on what you have given us thus far is to try jacking and shimming the perimeter of the house that is low until it is closer to level. (Left and top sides.)

You would also need to find out what the minimum standard is for the floor you will be installing, and try to get the floor flatter than that.





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Old 04-07-19, 02:33 PM
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Thank you for the response. I edited the picture to show the adjacent rooms. 3 of the walls are exterior, (top, left & right). I did think of jacking, but the exterior walls are CMU block and the interior has been insulated, framed and drywalled with the framing sitting on the subfloor on 2 walls and a brick veneer on the other wall with a fireplace. Jacking up the floor joists would damage all of this as well as jacking up the roof joists through the framing.

The door is located in a high area (red on sketch) so would not be affected by additions to the subfloor.

The products I am looking at show allowable flatness variation at 3/16" per 10'. I think the main trouble area is the center of the floor where the slope changes (highlighted in new picture).
 
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Old 04-07-19, 02:53 PM
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About all you can do is raise the whole floor by adding tapered sleepers on top of the low parts of the existing floor, then add an additional layer of 3/4 tongue and groove osb or plywood over the entire floor.

this will mean you will need height transitions at any doorways to the other rooms, and possibly your front door will need to be removed/replaced so that it will be high enough to swing over the new, higher flooring.

Demoing the existing subfloor to save some height is a possibility but it would likely require blocking at all interior walls and may be more work than you bargained for.
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Old 04-07-19, 03:51 PM
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Starting to make sense why the previous owner put carpet in there instead of laminate planks like the other living area. Underneath the carpet was small format irregular tile that look to be original (1960/70) which are in good condition with no cracks in the grout so I am thinking the floor was never level. Underneath the beam set in the block wall doesn't look degraded or to have shifted.

I am not as concerned about the height as the transition. If I add 3/4 underlayment + 3/8 -1/2 for the finished floors that is going to be a large step up. I have looked at this quite a bit and I'm guessing my inability to find a solution may be there isn't one, but is there a way to feather in the subflooring? ie do what you suggest and add 3/4 underlayment + Shims to one side (top half of picture) and then put in ~2-3' strips of 1/2, then 1/4 underlayment. Not sure how to feather the transitions to make it flat as the thinner plywood would need to be continuously supported. Maybe shimming underneath with shingles?

My original thought was self leveling compound. Lots of great reviews of the stuff, but forums seem to steer away from using it unless over concrete.
 
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Old 04-07-19, 03:58 PM
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You will need to put down lath for the SLC if you use it over wood.
 
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Old 04-07-19, 04:11 PM
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Without being there it's hard to say. If it was mine, I would cut about half of the subfloor out (you would need a toe kick saw to cut flush with the walls... worth every penny) near the center or near that corner on the left and remove everything that is more than -1/8. Leave the parts that are 0 or -1/8. Then shim your floor joists with tapered sleepers (or just sister along side) so that your joists are level. Then, assuming your existing subfloor is 3/4" thick, replace what you tore out with 3/4 tongue and groove that is glued and screwed.

The result would be a nearly level, flat floor with no elevation change other than adding your 5/16-3/8" laminate. It would also mean replacing all your baseboard, but you would likely do that anyway and add baseshoe after the floor is finished.
 
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