Q. I have a 20 year old house with a concrete basement floor. We want to create a play area for the kids. Before we install new flooring we are concerned that there are many areas of bubbling white powder. The floor has been painted but it still comes through. Can I build a wooden floor directly overtop of the concrete.
A. This is a sign of moisture coming through the concrete. It will continue to seep through, unless the existing paint is removed and the floor is sealed with a Crystallization Sealer such as Aquaseal available through Cloverdale Paint. To remove the existing paint, rent a heat gun and scrape as you go. Once the paint is removed, wash the floor with Shell Busey Home Cleaning Formula and then proceed to seal the concrete. There is a company called Basement Systems that specializes in waterproofing basements. They also carry a product that you can install yourself called Delta-FL which is a dimpled plastic membrane installed directly over the concrete once you have sealed it allowing the concrete to breathe while providing an insulated basement floor and warmer room. At this point you can lay your plywood sub floor, followed by the flooring of your choice.