How to Check Structural Integrity
With walls and floors exposed, this is your one chance to inspect for hidden damage. Water damage, rot, and mold that were invisible behind tile and drywall are now visible—and must be addressed before you close everything back up.
Quick Summary
Time needed
1-2 hours
Cost
Free (inspection)
Difficulty
Medium (knowing what to look for)
Why This Matters
Covering up water damage with new tile is a recipe for disaster. The damage will continue to spread, your new work will fail prematurely, and you'll face a much more expensive repair later. Take time now to catch and fix problems.
What You'll Need
Tools
- Flashlight (bright)
- Screwdriver or awl (for probing)
- Moisture meter (optional but helpful)
- Camera or phone for documentation
Safety Gear
- N95 mask (if mold present)
- Gloves
- Safety glasses
Where to Inspect
1. Around the Toilet Flange
This is the #1 location for hidden water damage. Failed wax rings cause slow leaks that rot subfloor for years.
Look for:
- • Soft, spongy subfloor when you press on it
- • Dark water stains in a ring pattern
- • Subfloor that crumbles or feels punky
- • Visible rot extending beyond the flange
2. Shower and Tub Wall Framing
Failed caulk, grout, or waterproofing allows water into wall cavities. Check studs behind the shower/tub area.
Look for:
- • Water stains running down studs
- • Black, green, or white mold growth
- • Soft or rotted bottom plates
- • Rust stains from corroded nails
3. Subfloor Condition
Walk across the exposed subfloor. It should feel solid and not flex excessively.
Look for:
- • Soft spots or sponginess underfoot
- • Visible water damage or staining
- • Delaminating plywood layers
- • Warping or buckling
4. Floor Joists (If Accessible)
If you can access the ceiling below (basement or crawlspace), inspect joists from below.
Look for:
- • Water stains on joist tops
- • Sagging or cracked joists
- • Rot around plumbing penetrations
- • Mold growth on joist surfaces
5. Plumbing Connections
While exposed, check supply lines and drain connections for leaks, corrosion, or damage.
Look for:
- • Mineral deposits indicating slow leaks
- • Corroded fittings or pipes
- • Signs of previous repairs or patches
- • Galvanized pipes (consider replacing)
The Screwdriver Test
A simple way to test for rot: Press a screwdriver or awl into suspected areas.
Healthy Wood
Screwdriver doesn't penetrate easily. Wood feels solid and resists pressure. Surface may be discolored but structure is intact.
Damaged Wood
Screwdriver sinks in easily. Wood feels soft, punky, or crumbles. This wood must be replaced before continuing.
When to Call a Professional
Frequently Asked Questions
What are signs of water damage in bathroom framing?
Look for dark water stains, soft or spongy wood, visible mold, musty odors, warped framing, and discoloration. Wood that crumbles when probed with a screwdriver indicates rot.
Can I fix rotted subfloor myself?
Small areas (under 2 square feet) can be cut out and replaced by a competent DIYer. Larger areas or joist damage should be evaluated by a professional.
Should I test for mold?
Visual inspection is usually sufficient. If you see significant mold (more than 10 square feet) or have health concerns, consider professional testing. Small surface mold can be cleaned.
What if I find damage?
Don't panic—it's better to find it now than after the renovation. Small repairs can be done before proceeding. Major structural issues need professional assessment.
Ready for the Next Step?
Once you've inspected for damage (and addressed any issues found), it's time to arrange disposal for all the demo debris.