How to Lay a Floating Subfloor over Concrete Part 1

Installing a floating subfloor over your cement floor can add warmth, homeliness and character to your room. By adding subflooring over your existing cement, you can create a floor that is appealing and that will act a barrier between the cold cement floor and your room. (This is Part 1 of a 2 part series. To move ahead to Part 2, click here.)

The Underlayment

A floating subfloor is flooring that actually never touches cement floor. The subfloor "floats" or rests on top of a waterproof underlayment. The underlayment may be made of various materials including polyethylene, plastic and styrofoam. The underlayment exists to create an air filled gap between the cement floor and subfloor. The air gap will help to insulate the floor and keep the room warmer. As well, the underlayment is always a waterproof material that will create a waterproof barrier between the subfloor and cement floor.

The Subfloor

Subfloors are strong, versatile and very durable. Subfloors are capable of sustaining heavy furniture or objects and stand up well to traffic. As well, the air gap created by the underlayment will give the floor a little bounce and create cushion. The underlayment adds a softer feel to the floor than you could get by just laying floor over the cement. Most types of subfloor come in 2 foot by 2 foot pieces that interlock to each other which will make installation relatively simple.

Step 1 – Inspect the Cement Floor

The first thing you should do is prepare the cement floor for installation of the subfloor. Check the floor for cracks, excess moisture or unlevel dips. If you find any of these issues in the cement floor, you should investigate and research further before installing the subfloor. If you find cracks in the floor, you should check the foundation of your home before proceeding. You should treat the cement floor with a concrete sealant prior to installation if you find that your floor seems damp, wet or that it collects moisture. If you have not previously treated your floor with a concrete sealant, you should go ahead and do this as a precautionary measure. The sealant will create a more waterproof barrier for the floor and will help protect the subflooring. If you find that your floor has dips or is unlevel, you should properly level the floor by using leveling compound.

Step 2 – Prepare for Installation

Next, you will want to make sure that the cement floor is clean by vacuuming and sweeping the floor to remove any dirt, soil or debris. Before you install the subfloor you need to let is breathe. To do this, remove the subfloor from any packaging and allow it to stand in the room where you will install it for at least 24 hours prior to your installation. When letting the floor pieces stand, it is best to lay the flooring plastic side down directly onto the cement floor. By allowing the subfloor to stand in the room, it will acclimate itself to the temperature and moisture content of the room.