Not sure if that spot on your ceiling or the musty smell in your bathroom is something to worry about? This free checklist walks you through the five places mold hides most in a home, so you can spot early warning signs before they become expensive problems. It’s the same 5-Zone Inspection System™ we use in our full Weighted Mold Risk Scorecard™ — quick enough to run in 30 minutes, thorough enough to catch what matters.
How This Checklist Works
Mold risk isn’t just about whether you can see it. Visible growth, physical damage, humidity, odor, and health symptoms all factor in differently. That’s why each zone below is scored on weighted risk factors, not just a yes/no list — physical damage and visible growth count more heavily than odor or humidity alone, because they’re the strongest indicators of an active problem. For more on why these particular zones matter, see The 5 Places Mold Hides in Every Home.
Safety note: Never touch a stain or spot you suspect is mold, even with gloves — physical contact can dislodge spores and spread contamination. Use a moisture meter to check saturation instead.
1. Bathrooms
- Check grout lines and caulking for dark or pink discoloration
- Look under sinks and around tub/shower surrounds for warped, bulging, or swollen material — check with a moisture meter, don’t touch
- Note any lingering musty smell after the room has aired out
- Check exhaust fan function — poor ventilation is the #1 driver of bathroom mold
2. Kitchen
- Inspect under the sink and around dishwasher/refrigerator water lines
- Check for staining or bubbling on cabinet bases near plumbing
- Look at ceiling areas directly below any upstairs bathrooms
- Note any condensation buildup on windows
3. HVAC
- Check vents and returns for dust buildup with dark specks
- Note any musty smell when the system first kicks on
- Check the drip pan and condensate line for standing water
- Look at accessible ductwork for staining
4. Windows / Exterior Walls
- Check window sills and frames for black speckling
- Look for peeling paint or bubbling drywall near exterior walls
- Note any water staining below windows after rain
- Check caulking and seals for gaps
5. Attic / Crawlspaces
- Look for dark staining on roof sheathing or rafters
- Check insulation for compression, staining, or a musty smell
- Note any daylight visible through the roof deck (ventilation gaps)
- Check for standing water or damp soil in crawlspaces
Already spotted something that looks concerning? See How to Know If a Stain in Your House Is Mold to confirm what you’re dealing with. For hands-on fixes, browse our Guides on moisture mapping and caulk repair, or check the moisture meters and other Tools We Recommend.
Call to Action
Ready for a more precise picture? Our full Weighted Mold Risk Scorecard walks you through all five zones with guided scoring, so you get an actual risk score — not just a checklist.