Question 1

Our condo board says we need STC-rated underlayment before installing new floors — what does that actually mean and how much more does it usually cost?

Accepted Answer

STC-rated underlayment is acoustic insulation designed to reduce sound transmission between floors in condominiums. Your condo board is requiring this to minimize noise complaints from neighbors below when you walk on your new flooring.

STC stands for Sound Transmission Class - it's a rating system that measures how well a material blocks airborne sound. The higher the STC number, the better the sound blocking. Most condo boards in Ottawa require STC ratings between 50-65 for floor assemblies.

Question 2

Our 1950s bungalow has original subfloor planks — is that stable enough for tile?

Accepted Answer

Original 1950s subfloor planks are typically not stable enough for tile installation without significant preparation. Most homes from that era have 1x6 or 1x8 diagonal planks that will move and flex too much for ceramic or porcelain tile.

Tile requires an extremely stable, rigid substrate to prevent cracking. Your original plank subfloor likely has some deflection (bounce) and the individual boards can shift slightly over time. Even small movements will telegraph through to the tile, causing cr

Question 3

What moisture reading is too high for hardwood install?

Accepted Answer

Moisture content above 12% in the subfloor or more than 4% difference between subfloor and hardwood is too high for installation. Most hardwood manufacturers require subfloor moisture below 12% and within 2-4% of the flooring material before installation can proceed.

Subfloor moisture standards are critical for preventing cupping, crowning, and gapping issues down the road. Concrete subfloors should test below 4.5% moisture content using a pin-type meter, or below 75% relative humidity using in

Question 4

The floors aren't level between rooms — can that be corrected before new install?

Accepted Answer

Yes, uneven floors between rooms can absolutely be corrected before your new flooring installation. This is actually a common issue in Ottawa homes, especially older properties, and addressing it properly is crucial for a professional-looking result.

Subfloor leveling is typically the solution for height differences between rooms. Licensed flooring contractors can use self-leveling compound, plywood buildup, or floor leveling systems to create smooth transitions. The method depends on how signi

Question 5

Should sagging floor joists be corrected before any new flooring goes down?

Accepted Answer

Absolutely yes - sagging floor joists must be corrected before installing any new flooring. Installing flooring over sagging joists will cause premature failure, cracking, and potentially void your warranty.

Sagging joists create multiple problems that new flooring cannot fix or hide. The structural deflection will cause hardwood to gap and crack, laminate joints to separate, tile to crack along grout lines, and vinyl to develop waves or tears. Even flexible flooring materials like carpet will

Question 6

There's old adhesive residue stuck to the concrete — how is that removed properly?

Accepted Answer

Old adhesive residue on concrete requires mechanical removal and chemical stripping to create a proper surface for new flooring installation. The removal method depends on the adhesive type, but most require professional-grade equipment to avoid damaging the concrete substrate.

Mechanical removal is typically the first step and most effective approach. Professional contractors use floor grinders with diamond grinding wheels, shot blasters, or scarifiers to mechanically strip away the adhesive.

Question 7

Our floor slopes toward one corner — is that normal settling or serious?

Accepted Answer

Floor slopes are rarely "normal settling" and usually indicate a structural issue that needs professional evaluation. While minor settling can occur in any home, noticeable sloping typically points to foundation problems, structural beam issues, or inadequate support that requires attention before any flooring work.

Identifying the severity depends on how much slope you're experiencing. A gentle slope of 1/4 inch over 10 feet might be acceptable in older homes, but anything more pronounced - es

Question 8

Can OSB subfloor cause problems with certain types of flooring?

Accepted Answer

OSB (oriented strand board) subfloor can cause significant problems with certain flooring types, particularly moisture-sensitive materials like hardwood and laminate. The main issues stem from OSB's tendency to swell, telegraph surface texture, and potentially off-gas formaldehyde.

Moisture-related problems are the biggest concern with OSB subfloors. OSB absorbs moisture more readily than plywood and swells significantly when wet, which can cause hardwood floors to cup, buckle, or develop gaps.

Question 9

Is self-leveling compound necessary for every flooring installation?

Accepted Answer

Self-leveling compound is not necessary for every flooring installation, but it's required when your subfloor has significant height variations that exceed your flooring material's tolerance levels.

Most flooring materials have specific flatness requirements. Hardwood and laminate typically require the subfloor to be flat within 3/16" over 10 feet, while luxury vinyl plank (LVP) is more forgiving at 1/4" over 10 feet. Tile installations demand the strictest tolerances - usually within 1/8" over

Question 10

How thick should the plywood subfloor be for hardwood installation?

Accepted Answer

For hardwood flooring installation, plywood subfloor thickness should be minimum 5/8" (15.9mm), with 3/4" (19mm) being the preferred standard for optimal stability and performance.

The 3/4" plywood subfloor provides the best foundation for hardwood installation because it minimizes deflection and movement that can cause squeaks, gaps, or premature wear. This thickness works well with both nail-down solid hardwood and engineered hardwood installations. The additional rigidity helps prevent the s

Subfloor Preparation