luxury vinyl planking - underlayment flatness


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Old 08-30-15, 10:02 AM
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luxury vinyl planking - underlayment flatness

I am installing luxury vinyl planks 5"W X 48"L and am currently evaluating my luan ply subfloor for flatness. (I have removed the old vinyl tiles from the subfloor.) I have found two rectangular areas of the floor that are each about 7' long X 24" wide. Both areas run along walls. The outer edge of these areas (24" from the wall) are flat with the rest of the floor but from the outer edge to the wall they gradually dip to 1/2" lower than the rest of the floor.

One of these areas runs parallel to the length of the planks to be installed and the other area runs parallel with the end of the planks.

I was considering using a troweled flooring compound to fill-in these areas but am concerned, due to the size of these areas and my lack of masonry skills, that I might not be able to achieve the required "accuracy of incline" I need with a troweled product across the 7 foot areas. I have been advised against using true self-leveling compound (pancake batter consistency) due to my luan ply underlayment and the risk of delamination.

I have experimented with a couple of planks clicked and locked together (this is a floating floor) and because they are so flexible it seems that the dip in the contour of the floor in these two areas isn't a problem. The planks seem to conform to the contour of the floor perfectly. I should add that the two areas I am talking about are not areas where people stand or walk. They are visible however.

Any comments for or against the idea of installing planks without first leveling these two areas? Any ideas would be appreciated.
 
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Old 08-30-15, 12:53 PM
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First off, Luan is not an approved underlayment material. Are you sure it isn't underlayment grade Plywood? There are too many voids in the center of Luan that may transfer to the topside of the flooring. It also could delaminate if conditions are not optimal.

That being said, as a click lock floating floor, I would test lay more that a couple of planks and better simulate the whole floor install. Make sure you don't have any breaks directly over the hump (most likely a out of alignment joists). If all seems fine, I would proceed with the install. Remember, the hump was present in your old floor set up and unless it was terribly noticeable, it should be fine on this one. If it bugs you, you can peel back the floor and correct later on.

The reason you can't use straight self leveling compound is that you need to add lath to give it something to grab over a wood subfloor. You also put felt paper down under the lath so that the wood doesn't suck all the moisture out and mess with the bond.
 
 

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