Leveling floor, after installing 1/4" plywood underlayment

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Old 01-12-15, 07:01 PM
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Leveling floor, after installing 1/4" plywood underlayment

Hello everyone,

This gets complicated, so please bear with me. Long post below, but here is my main question for those who just want to respond to the question:

Can I apply Self Leveling Underlayment over 1/4" plywood underlayment using metal lath to level a floor in anticipation to install Vinyl Plank tile flooring?

Here is the lengthy details:

I started this thread: http://www.doityourself.com/forum/vi...-flooring.html with the hopes of installing VPT flooring. I then changed my mind and wanted to do ceramic tile, but went back to the idea of wanting to do the VPT because of cost, ease of installation and because our kitchen floor would not be raised that much with installing the vinyl, whereas with the ceramic tile, our kitchen floor would be about a 1 1/2" above the dining room after the underlayment and backer board is installed.

My GF and I did not want the kitchen floor to be raised that much above the dining room (trip hazard among other things), and so we could get the kitchen done sooner, since we already had everything on hand for the vinyl.

Here is the problem. We have 1x3 T&G plank subfloors. The floor are mainly flat/level, but I then found out that there was a dip in the corner by the exterior door that dipped about a 1/2" (close to 3/4" in a small section). With my plan to install 1/4" underlayment plywood for the vinyl, I decided to try and level the subfloor with roofing shingles. In my attempt to level the subfloor, then install the 1/4" plywood, I only reduced the dip by half (so there is still a 1/4" dip and some spots up to a 1/2" dip). The dip is noticeable and I don't want to leave it that way. I don't know the root cause of the dip, but being a 1920s row home, my suspicion is that the house settled or the floor shifted over time to cause the dip. The 3x8 16" OC joists are solid.

Additionally, I have already install the drywall and I am about 90% done.

Is a suitable solution to use self leveling underlayment over the 1/4" plywood underlayment?

I've read the instructions for the Custom Building Products Rapid Setting SLU and for plywood installations, I need metal lath with a minimum of 1/4" SLU to be applied.

Would this solve my problem?

Thanks.
 
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Old 01-12-15, 07:25 PM
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Got a mess there.
1 X 3 is not a subfloor, it's old pine or hardwood flooring (no pictures or enough info, so have to guess)
Going to have to go back and figure out what's below that floor to figure out if it will work with tile.
What's the spans, spacing, and width of the joist?
Rule of thumb, 1/4" is never used under tile, 8" wide joist would be the bare min. for even carpet or linoleum, never acceptable for tile .
 
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Old 01-13-15, 03:20 AM
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It's 3x8 joists 16" OC, then the planks. I'm not sure of the species, but this is the same subfloor throughout the house. The rest of the house is hardwood. In our kitchen, there was vinyl glue tile on top of some type of 1/4" board (it wasn't plywood), then planks, then joists.

We have decided ceramic tile is out, but we are trying to move forward with the vinyl plank tile (allure grip strip). I installed the 1/4" plywood as the underpayment for the allure, and thought the floor was flat and level until I saw the dip after I stapled the underpayment down. I tested every which way with my level before the underlayment was stapled, but I didn't realize that the dip was still there until afterwards.

Thanks.
 
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Old 01-13-15, 03:42 AM
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Optimally, you would like to level the floor underneath the 1/4" plywood. While the SLC does seek its own level, it does not feather finish as well as you probably would like for vinyl. The problem with vinyl is that it will show any imperfections through it, so you want things super flat. I would remove the 1/4" in the area with the low spot. Fill according to instructions using lath and primers. Get some Custom Building Supply Speed Finish to feather the edges. Then re-install your 1/4" and skim the seams and nail/staple holes with the Speed Finish.
 
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Old 01-13-15, 05:40 AM
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Optimally, you would like to level the floor underneath the 1/4" plywood.
Thanks.

I had a sleepless night thinking that this was what I ultimately had to do. Since the area in question is only 3'x3', I figured I could remove the plywood and try to correct the leveling with the roofing shingles.

In fact, I think part of the problem is that when I used the shingles, I brought them too far away from the depressed area to 'merge' into the level floor and this caused a problem.

My plan now is to remove the small section of the plywood with staples, and adjust the placement of the shingles and build up the dip to level off. I left a couple pieces of leftover 1/4" plywood outside and it got wet, so hopefully I can re-use if it dries well as I'm sure, I will ruin the currently stapled plywood when I try to remove it.

If this works, I won't even have to use the leveling compound.

Thanks.
 

Last edited by supersnake83; 01-13-15 at 06:20 AM.
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Old 01-18-15, 06:09 AM
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I pulled up the affected areas and removed the abundance of roofing shingles that was causing my problem. I only had to remove about 7ft x 5ft. This was a lot for me since I had to manually remove a lot of staples.

The problem was I overlapped too many shingles, thinking I was dong the right thing. After I pulled everything up and relayed the shingles, I noticed that I just should have put one layer in the affected areas, then build up only the areas where the depressions was very noticeable. For me, this was in a corner, so I laid one layer, then added a layer or two on the edge. This made the floor level again.

I returned the self leveling underlayment, but had to purchase another piece of plywood underlayment. Save some cash and thankful for avoiding a headache.

I couldn't use the self leveling underlayment on my subfloor since my 'subfloor' is plank wood.

Thanks everyone.
 
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