When Edmonton homeowners picture a flooring installation, they usually think about the product going down — the new hardwood, the fresh LVP, the clean tile. What most people don’t think about is what happens underneath. But the truth is, the single biggest factor in how well your new floor performs over the long term isn’t the product itself — it’s the subfloor it’s installed on.
Proper subfloor preparation for flooring installation is what separates a floor that looks great and holds up for decades from one that squeaks, shifts, or fails within a few years. Here’s what it involves — and why it matters especially in Edmonton homes.
What Is a Subfloor?
The subfloor is the structural layer beneath your finished flooring. In most Edmonton homes, it’s either plywood or OSB (oriented strand board) over floor joists, or a concrete slab — common in basements and main-floor additions built on grade. The subfloor is what your installer is actually fastening, gluing, or floating your new floor onto.
The finished floor you walk on is only as good as the surface it’s bonded to. If the subfloor is uneven, wet, soft, or unstable, those problems will telegraph straight through to your new floor — no matter how premium the product.
What Does Subfloor Preparation Involve?
Flatness and Levelling
Most flooring manufacturers require the subfloor to be flat within a certain tolerance — typically 3/16 of an inch over a 10-foot span. Any high spots or low spots beyond that need to be addressed before installation begins.
High spots on wood subfloors are sanded or planed down. Low spots are filled with a floor levelling compound that dries hard and smooth. On concrete, self-levelling compound is used to bring a dipped or uneven slab up to spec.
This step is critical for floating floors like LVP and laminate, which will flex and eventually crack at the locking joints if the subfloor underneath them has significant dips or humps.
Moisture Testing
Moisture is the enemy of most flooring products — and in Edmonton, it’s a year-round consideration. During summer, ground moisture can migrate through concrete slabs. In older homes, minor plumbing leaks or inadequate vapour barriers can create elevated moisture in wood subfloors.
Before installing hardwood, engineered hardwood, or laminate, a professional installer should test moisture levels with a calibrated moisture meter. For concrete subfloors, a calcium chloride test or relative humidity test may be used to check vapour transmission rates.
If moisture levels are too high, the problem needs to be addressed at the source — or the right moisture barrier and product combination needs to be selected before installation proceeds.
Structural Integrity
Soft spots, squeaky boards, or flexing in a wood subfloor are signs of underlying issues — whether that’s a loose subfloor panel, a failing joist, or inadequate fastening. These need to be repaired before any new flooring goes down.
Squeaky floors that exist before installation will often get worse after, as the new flooring adds weight and movement. A good installer will walk the subfloor carefully, identify problem areas, and address them — either with additional screws to re-secure panels, or by flagging structural issues that need attention before work continues.
Removing Existing Flooring
In many renovation projects, the first step is removing what’s already there. Old carpet and underpad, vinyl sheet flooring, tile, or laminate all need to come up before new flooring is installed. Each material has its own removal considerations:
- Carpet: Relatively straightforward to remove, but the tack strips around the perimeter need to come up and be inspected
- Ceramic or porcelain tile: Labour-intensive to remove, and often leaves adhesive or mortar residue on the subfloor that needs grinding
- Glue-down vinyl or LVP: Adhesive residue can be challenging to remove completely and may require a floor scraper or chemical treatment
- Old hardwood: Sometimes left in place as a subfloor layer; sometimes removed depending on the height difference and product being installed
Why Edmonton Homes Have Unique Subfloor Considerations
A few factors make subfloor preparation particularly important in Alberta:
- Developed basements: Edmonton homes with finished or semi-finished basements frequently have concrete subfloors that need careful moisture assessment before hardwood or laminate is installed
- Older home stock: Many Edmonton neighbourhoods have homes built in the 1950s through 1980s with subfloors that have seen decades of use — and sometimes water damage or settling that needs correction
- Seasonal humidity swings: The dramatic difference between summer and winter humidity in Edmonton means wood subfloors can move seasonally — any existing looseness or squeaking tends to get amplified through the winter months
- Ice melt and entry moisture: Mudrooms and entryways in Edmonton homes see significant moisture from winter boots and ice melt tracked inside — making proper moisture barriers in these areas especially important
What Happens If Subfloor Prep Is Skipped?
Cutting corners on subfloor preparation is one of the most common causes of flooring failures. Here’s what can go wrong:
- Floating floors crack or separate at the locking joints over uneven subfloors
- Glue-down floors develop hollow spots or lift over areas with high moisture
- Nail-down hardwood squeaks and shifts over loose subfloor panels
- Tile grout cracks over a subfloor that has any flex or movement
- Hardwood cups, warps, or develops gaps due to unaddressed moisture issues
In many of these cases, the floor needs to be pulled up and the subfloor work done properly before reinstalling — costing far more than doing it right the first time.
Trust the Professionals to Get It Right
At LCF Flooring, subfloor preparation is a standard part of every installation — not an afterthought. Our team inspects, levels, tests, and repairs before a single plank goes down, so your new floor has the foundation it needs to last.
Browse our residential flooring services or check out our project portfolio to see the quality of our installations. Ready to get started? Contact us for a free quote — we’ll assess your subfloor as part of the process at no charge.