We had a room that animals chose to use as a latrine. I have pulled all of the carpet and revealed the fiberboard beneath. After sanding it to get any layer of pee-wood up, I am going to coat it with KILZ primer.
We are going to get padding so this question is probably moot, but would the KILZ alone be enough of a moisture barrier to lay hardwood/vinyl/pergo/etc. directly on top of it and the fiberboard (not concrete)?
What is under the fiberboard, what kind of fiberboard is it, and what kind of padding are you looking at? Some types of padding provide a moisture barrier. If the fiberboard is directly on top of concrete you need a vapor barrier somewhere, ideally beneath it (underneath the fiberboard, not underneath the concrete which would be rather expensive to install now).
But would the KILZ serve as a moisture barrier? That’s the question.
It is better than paint, but not as good as an independent barrier. It can be worn down over time much more easily than something designed for floors.
If it’s simply painted on the fibreboard, and the board cracks from use, then the surface it’s painted on is no longer a vapour barrier. An ideal vapour barrier paint would - like a plastic coat - be sealed everywhere, and if the underlying surface cracks, then it would need to be “gummy” to allow the two sides of the crack to adhere to each other and ensure the crack remains air/water tight. Is KILZ this sort of material?
My go-to reference for home building, Holmes on Homes says that wood should never be placed directly on concrete without a barrier. Our latest home, the year after it was built the concrete basement walls exuded a huge amount of water that oozed through the bottom of the vapour barrier and soaked the carpet. (But not since then…) OTOH, if the wood has survived intact since it was first put there, then odds are the moisture risk is low (at least with plain water, from below…)
There is a basement waterproofing version of it. I would use padding that provides a moisture barrier anyway.
Thanks all. There was no moisture barrier between the fiberboard and carpet padding but it pays to be sure.
What do you mean by fibreboard?
Most homes built since the early nineties will have OSB subfloors, older homes will have plywood. Particle board underlay is only fastened over the subfloor when installing sheet vinyl or other products that require a smooth surface. Manufactured homes use a particle board subfloor so that vinyl sheet flooring can be installed directly on the subfloor.
Basement or other concrete floors should be prepped according to the floor product manufacturers requirements. Usually this will just be use of a recommended underlay. All 6 mil poly will provide is a level of vapour retardation. There are underlays that will provide similar vapour retardation.
The next step up is a dimpled membrane like Delta, or floating subfloor system like Dricore. These will add warmth and tolerate some moisture.
Ceramic tile is really the only floor product that tolerates moisture.