Bathroom
The room with the highest moisture exposure and the second-most plumbing complexity. Toilets, sinks, showers, tubs, vent fans, and constant humidity management.
Overview
Bathrooms concentrate plumbing fixtures and constant moisture into a small space. Every failure mode is either a leak (drips into cabinets, walls, or subfloor), a clog (sinks, toilets, showers, tubs), or a moisture problem (mold, mildew, fan failure, exhaust ductwork issues).
Most bathroom fixes are simple, cheap, and fast. Toilet fill valves and flappers, sink pop-up cleaning, shower hair removal, and faucet cartridges account for the vast majority of homeowner-fixable issues. The exceptions requiring pros: tile work in showers (waterproofing failure risk), whole-fixture replacement, and structural repairs from long-term water damage.
Most common fixes in this room
The highest-search-volume issues for this space, each fully documented with safety-first framing, ranked causes, and cost estimates.
By category
Every corner of this room, organized by what's involved. Click any sub-category for the full inventory of fixes and projects.
Toilet
Running, weak flushes, clogs, leaks, replacement.
Sink & vanity
Drains, faucets, pop-ups, vanity installation.
Shower & tub
Drainage, diverters, tile issues, caulking, glass doors.
Ventilation
Exhaust fans, ductwork, humidity control.
Tile, grout & moisture
Grout maintenance, tile repair, mold prevention, caulking.
Bathroom electrical
GFCI, vanity lighting, heated towel rails.
Materials used in this room
Tools for this room
Project cost guides
Bathroom moisture management
Humidity is the enemy — control it or pay for the damage later:
- Run the exhaust fan during every shower and for 15 minutes after.
- Fan should be sized to bathroom square footage (see fan sizing calculator).
- Fan must vent to exterior — not just into the attic (a common code violation that causes attic mold).
- Recaulk showers every 3–5 years — old caulk cracks and lets water into walls.
- Address small mold spots immediately; large mold (>10 sq ft) requires professional remediation.
Frequently asked questions
Every 10–20 years typically. Signs it's time: missing pieces of grout, cracks running along grout lines, discoloration that won't clean up, or water pooling behind tiles. Small grout repairs can extend life significantly.
Wall tile in a dry area (kitchen backsplash) — yes, DIY-friendly. Shower walls or floors — no. Waterproofing failures behind shower tile cause massive damage; a $2,000 professional install prevents a $20,000 rebuild.
Vent ductwork is blocked, disconnected, or too small. Common find: fan installed but ductwork was never connected to the exterior vent, so it just moves air around the attic. Check for airflow at the exterior vent hood.
For small surface mold spots on non-porous surfaces (tile, glass, sealed surfaces) — yes, cleaner and undiluted bleach works. For porous surfaces (drywall, wood, grout) — bleach only surface-cleans; the mold roots deeper. Larger mold problems require professional remediation.