My new shower tile grout is cracking after only a few months — what went wrong?

Grout cracking after just a few months typically indicates movement in the substrate, improper grout mixing, or inadequate curing conditions during installation. This is unfortunately common in Vancouver's wet climate when proper waterproofing and substrate preparation are skipped.

The most likely culprit is substrate movement behind your tiles. If the installer didn't properly prepare the shower walls with a rigid backer board (like Hardiebacker or Schluter Kerdi board), or if they tiled directly over drywall or poorly-secured plywood, the substrate flexes when you step in the shower or lean against walls. Even tiny movements cause rigid grout to crack. In Vancouver's older homes, this is especially common with wood-framed bathrooms that weren't built to modern standards.

Waterproofing issues are another major factor. The BC Building Code requires proper waterproof membranes in shower areas, but some contractors still cut corners. If water is getting behind the tiles through inadequate waterproofing, it can cause the substrate to swell and shift, leading to grout failure. Given Vancouver's high humidity and our long rainy season (October through March), moisture infiltration problems show up quickly.

Installation factors could also be at play. If the grout was mixed incorrectly (too much water makes it weak), applied in cold conditions (below 10°C), or not allowed to cure properly, it becomes brittle and prone to cracking. Some installers rush the job and don't clean excess grout properly, leaving weak spots.

Professional assessment is crucial here because cracking grout often signals bigger problems. A qualified tile contractor should inspect the installation to determine if this is just a grout issue or if the waterproofing and substrate need attention. Simply re-grouting over the same problems will lead to the same failures within months.

Next steps: Document the cracking with photos and contact your installer if the work is still under warranty. Most reputable contractors guarantee their work for at least one year. If the installer isn't responsive or the work is out of warranty, have an independent tile specialist assess the installation. Depending on the extent of the problem, you might need anything from simple re-grouting ($200-500) to complete tile removal and proper substrate preparation ($2,000-5,000+ for a typical shower).

Don't delay addressing this — water damage behind tiles can lead to much more expensive structural repairs in Vancouver's wet climate.