Around The Home, Renovations

Does your Basement Need a Subfloor?

Home Hardware
  • February 12, 2016


Making your basement more comfortable is important for every family – especially during a cold winter. Whether you’re finishing your basement, considering new flooring, or thinking about ways to improve its insulation, a good quality subfloor should be an essential part of the process.

What is a Subfloor, Anyway?

A subfloor is a base for your actual basement flooring. It consists of panels installed directly onto the concrete floor to provide a more comfortable base. A subfloor system such as InsulFloorBoard also provides an insulation value of R3 – which means it will increase your basement floor’s temperature by a minimum of 6º C.

In new construction jobs, it’s mandatory to install insulation under a concrete slab. But in the case of renovations, you’ll have to install a subfloor above the concrete. A subfloor isn’t an absolute requirement. But if you’ve simply laid a carpet or laminate flooring directly onto your basement floor, a subfloor can definitely make the floor – and therefore the entire basement – more comfortable, not to mention protect against moisture damage from water infiltration.


The Benefits of a Subfloor

Insulfloor’s subflooring system consists of a two-piece panel: the ESP (expanded polystyrene – a rigid insulating foam) layer, which goes face-down on your concrete floor; and a wooden OSB (oriented strand board) panel on top of that. The glue that binds the two together acts as a vapour barrier – important because concrete is porous, which means there will eventually be some moisture coming up through it. This vapour barrier allows moisture and humidity to rise up from the concrete and through the ESP without penetrating the OSB panel (which prevents the growth of mold).

The ESP foam layer insulates and helps keep the floor warm, while also preventing condensation by keeping the temperature of the concrete floor from coming into contact with the warmer basement indoor air. Plus, Insulfloor subfloor panels are only one-inch thick, which means you won’t have to trim your basement doors to accommodate it (in addition to whatever flooring you lay on top of it).


Common Questions

One common concern is moisture and water damage. Generally speaking, if your basement does flood, the subfloor will eventually dry out with the help of some fans. The ESP is a breathable, eco-friendly material that can absorb a certain amount of moisture before slowly releasing it.

The polystyrene material is waterproof and does not rot. Its grooves allow moisture to travel underneath, allowing it to easily drain. However, if your basement tends to flood, it’s advisable to address water infiltration issues before you consider installing a subfloor.

Floating or Fixed Installation

Depending on the type of flooring you install, you’ll either choose fixed or floating installation. If you’re installing ceramic tiles or hardwood flooring, you need fixed installation to ensure that the panels will never, ever move. You’ll need to glue the Insulfloor subfloor to the concrete floor (using LePage Premium Glue) and add a layer of plywood atop it for sufficient rigidity. However, for basements, hardwood flooring isn’t recommended as the risk of water damage is too high considering the greater cost of hardwood.

If you’re laying down carpet, other tile or laminate flooring, you’ll opt for floating installation. In that case, all you have to do is glue the Insulfloor at the joints. Once you’ve laid the Insulfloor subfloor down, leave about a quarter-inch perimeter from the walls to allow for contraction and expansion. You can then lay your preferring flooring material down (generally carpet, tile or laminate) on top of it.

Before subfloor products such as Insulfloor were readily available, each subfloor component – from ESP to OSB to a vapour barrier –had to be installed separately. Fortunately, today installing a subfloor is a much easier way to ensure your basement is both comfortable and protected against moisture damage and mold.

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