Can I install tile over a plywood subfloor?

No, you should not install tile directly over plywood subfloor. Plywood alone doesn't provide adequate support or moisture protection for tile installations, which can lead to cracking, loose tiles, and water damage.

Proper tile installation requires a stable, moisture-resistant substrate. The plywood subfloor is just the foundation - you'll need to install an appropriate underlayment system on top. For bathroom applications, this typically means installing cement backer board (like Hardiebacker or Durock) or an uncoupling membrane system (like Schluter-Ditra) over the plywood. These materials provide the rigid, waterproof base that tile needs to perform properly over time.

In Ottawa's climate with temperature fluctuations, proper substrate preparation is especially important. The wood subfloor will expand and contract with seasonal changes, and without proper underlayment, this movement transfers to the tile causing cracks. Additionally, Ontario Building Code requires proper waterproofing in wet areas like bathrooms - simply tiling over plywood doesn't meet these requirements.

The plywood itself should be at least 1-1/8" thick total (typically 3/4" subfloor plus 1/4" underlayment plywood) to minimize deflection. Any squeaks, loose areas, or deflection in the subfloor must be addressed before installing the tile underlayment. The surface should also be clean, level, and free of any wax, paint, or other contaminants.

For a bathroom tile installation that will last decades without problems, have a licensed contractor properly prepare the substrate with appropriate waterproofing and underlayment systems. This investment in proper preparation will save you from costly repairs down the road. For a free estimate on your tile installation project, request a quote from Ottawa Bathrooms.