Once you decide to use an engineered laminate hardwood floor in your basement, controlling the moisture is of the highest priority. Basement moisture can cause the hardwood flooring to cup, warp and swell. A few simple steps at the beginning of a project can save a lot of heartache later.
Since the basement is below grade, groundwater and water vapor can penetrate into the area and damage the basement's hardwood flooring. While the concrete in a basement floor looks solid, it can actually allow water vapor to pass through. Also, any cracks in the slab can let ground water into the basement.
When building a new home, be sure the builder specifies porous backfill (gravel) under the basement concrete slab. This will allow any groundwater present to flow to a ground water collection system. This groundwater collection system can then drain the water either to a sump pump, or in some home site locations the water can drain outside to daylight.
On top of the porous backfill should be placed a vapor barrier. The vapor barrier is usually a 6 mil polyethylene sheet. This will keep water vapor from passing through the concrete slab and into the hardwood flooring.
On top of the concrete slab and prior to installation of the basement hardwood floor, another vapor barrier should be installed. These vapor barriers can be:
- PVC applied over the slab with a multipurpose adhesive.
- 6 mil polyethylene sheets embedded into a skim coat of asphaltic mastic.
- 15 pound roofing felt embedded into a skim coat of asphaltic mastic.
Some manufacturers of engineered hardwood floors have their own recommendations and these should be followed. Any vapor barrier used should be checked for compatibility with an engineered hardwood floor manufacturer's system.
Installation of a basement hardwood floor is not recommend for a period less than 30 days after the concrete slab has been poured. This is because water is one of the components of concrete and a sufficient amount of time must pass for this water to be cured from the slab. A moisture content check of the slab prior to installation is recommended.
Heating and air conditioning systems should be operational at the time of installation. If it is during cool months, the furnace will help dry out the slab. And in warm months, the air conditioner will reduce the moisture content in the basement.