Heritage Restoration, Inc.

Best Basement Floor

We had a bit of water in our basement recently. There is carpet over a concrete floor, and the concrete floor is old and uneven. I was wondering what the best way or product to use when installing a new carpet or floor?

 Steve, Wakefield

We have seen a lot of problems caused by this wicked season, mainly ice, snowmelt, and water. The harsh winter conditions caused water to infiltrate buildings in ways it may not have ever before. The conditions could have exacerbated what could already be a problem, such as a basement with an old concrete floor trapping moisture or allowing water to come in.

A proper concrete floor is a system that prevents water and moisture from migrating through. How the concrete slab was prepared depends on the age of the floor, and your building site, if there is a high water table or direct water infiltration. A high water table could be resolved by a perimeter French drain system under or at the edge of the floor, allowing water to be captured and pumped out of the basement. A proper floor would also have several inches of stone, a 6-mil thick plastic sheeting on top, with concrete poured on top. This system can prevent moisture and direct water flow through the slab.

But you probably do not have this system and certainly do not want to start over. So then what? Well, some overlay techniques and technology have developed some solutions, some good, some not so good.

 Plastic, Paint, or Rigid Foam Insulation over the Slab
Plastic, paint, or rigid foam do not prevent water from coming through the slab. Water pressure will always find a way through. These systems can trap water and create mold and mildew problems. They are best for a dry concrete slab.

Basement Underlayment Products

These systems are inorganic and nonabsorptive, keeping an air space between the concrete and the finish floor. They are designed to allow water to move freely and allow some airflow to allow moist areas to dry. They act as a vapor barrier and can provide some thermal protection as well.

The challenge is determining how uneven your concrete floor is, since you don’t want trapped water. The best concrete floor is either perfectly flat or slightly pitched to a sump of edge perimeter drain system. You can use a good leveling compound over the concrete, or just leave it if it isn’t too bad.

The bottom line is you don’t want to install padding and carpet or a floating wood floor right over the slab, especially if you are getting water infiltration or condensation causing a potential for mold growth.