Insulating a Basement Floor

 By Matt Weber

Insulate your basement by installing a floating subfloor.

Is your basement nothing more than an unfinished storage area? That’s the case with many homeowners who consider their basement to lack the warmth and coziness to make it a comfortable living space. When it comes to cold basements, you can blame the floor. The porosity of a concrete floor can make it cold and damp—unwanted characteristics that can be felt through tile, carpet and hardwoods. Simply put, cold basements—even if they’ve been finished—often don’t get as much use as the other more comfortable areas of the house. That’s a lot of space going to waste.

Today, floating subfloor systems offer homeowners a way to stifle the cold and construct a warm, pleasant place for a game room, office area or home theatre. These systems offer a two-pronged approach to keeping concrete floors dry and warm.

First, the plywood or oriented strand board (OSB) subfloor floats on a channeled or “cleated” waterproof underlayment, so the wood never actually touches the floor. The underlayment material can be made of Styrofoam or heavy-duty polyethylene, the same material used in corrugated plastic drain pipe (one of the toughest plastics available). This underlayment creates an air gap above the concrete. Combined with the wooden panels, the air in this space provides a thermal break that acts as insulation to keep floors and rooms warm. These systems can warm a room as much as 10 degrees.

Second, that same layer of insulation provides a moisture barrier against the dampness that naturally rises through concrete slabs. Thanks to the channels in the underlayment, any moisture that does collect can easily drain and evaporate. This protects furnishings and inhibits musty smells and mold growth, ensuring a healthy living space.