I'm installing VCT tile in a new apartment, but after I ripped up the 100 year old carpet I'm finding masonite. The problem is the leveling compound and primer are picking off the masonite. The primer is note the worst case, but the leveling compound picks up way too easy.

To relay the floor with ply is $400. I'd like to weigh this decision against the possibility of using another leveling product that will actually bond to this underlayment.

  • Apartment? Are you the tenant?
    – Michael Karas
    May 4 '16 at 3:35
  • 1
    It may be worth the expense to truly fix this, with no wondering if your solution will work. May 4 '16 at 12:26
  • I think unfortunately, if the leveling compound is not one contiguous smooth surface, you're deal with quite a bit of flex/deflection. This could be trouble for the VCT in the future. I guess the question, is do you want to build a 2, 5, or 10 year floor? May 4 '16 at 14:09
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    I'd read the label on the leveling compound and see what it's listed to stick to. Worst case, make su it's not asbestos, then get some nice heavy sandpaper and scuff up the masonite so it has a rough surface. Nothing is going to stick to a glossy surface. You may need a barrier coat, something that will stick to masonite that leveling compound would stick. May 5 '16 at 10:34

The Masonite coverage was sufficient that replacement was not trivial. Since this is an apartment and not my own home, cost was a factor. The first good thing I did was take out those pieces which had water damage as no solution seemed to make good in that case. The board is just brittle and flakey, so it's not a matter of sticking, but of simple falling integrity.

I covered the rest with a fast drying primer, thinned down somewhat.

The replaced sections use AC plywood, because I couldn't source enough Masonite and needed to finish the same weekend and move in. Now I have something to compare to and I can say both sections appear to be holding equally well.

So the answer is to use a primer over the Masonite and the leveling compound.

One note of caution, the underlayment was nailed down and the subfloor are planks, so it seems some nails were loose in the grooves. Also, I screwed down the underlayment which further pulled down the sheets. Over time I'm seeing small 'pimples' in the floor! I should have taken up these nails. Meh. What are you going to do?

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