To fill out some dips in my floor prior to installing laminate, I visited
the local hardware store for advice. They sold me a bag of "Mapei
Ultraplan 1" self-leveling underlayment. The bag instructions laid out
only the water-mix ratio for mixing the entire bag. Since I didn't need
that much, I visited the web site to get clues on how to mix smaller
In reading the technical documentation, I wasn't much further ahead in
understanding how to mix a partial bag. But, one thing I noticed was the
direction on where you can apply the product. It can be applied over a
playwood sub floor like mine, but only 1.5" in thickness. Mine is
standard 1/2 inch.
The product I used in another room of my house was "Lepage Poly
Underlay" - it had no such subfloor thickness prescription (the store was
out of this product, which is why I ended up buying something different)
I'm guessing that the 1.5 inch limitation on the Mapei product is there
for a reason, and I'd be better off not testing that limit. I should go
back to a product that meets the specs of where I am installing it.