Got a musty smell, a stain, or a feeling something's off? A room-by-room guide to where moisture hides, what to look for, and what to do when you find it.
Already know you need a lab test? Order a home mold test kit from our partner HomeSAFE.
Get a test kitThis guidebook is meant to explain each step of the process, in the order you would work through it. Here is what each part covers.
The biology of mold, and how it develops in a home.
Everything else in the guidebook rests on this. Once you understand what mold needs and how it spreads, the rest of the process stops feeling like guesswork.
Find the moisture you can't see.
These tools help you identify moisture problems inside your home, including ones you didn't know were happening. A stain shows where water has been. A reading shows whether it's still there.
Know what a test can and can't tell you.
What each kind of test is for, and when to skip it.
The early clues, before anyone sees mold.
Learn what the common signs look like and what they point to.
One area of the home at a time.
Interactive floor plans and checklists for 12 areas, from bathrooms to attics and crawlspaces.
What to do in the first day or two.
Found water where it shouldn't be? What to do right away, how clean, gray and black water differ and why the last two need professionals, and what to know about insurance.
What mold looks like, and what to do about it.
You've found something that looks like mold. What it typically looks like on different building materials, what you can safely wipe off, and when to leave it for a professional to scope.
Two different jobs.
Who figures out what's wrong, who fixes it, and why they should be separate companies.
Moisture control, room by room.
Humidity and airflow habits, the tools that help, and what to do in each area.
If you only want to sample or measure something, these two kits from our partner HomeSAFE are available on their own. The guidebook shows when and where to use them, and includes a 10% off code for both.
For a suspicious spot you'd like a lab to examine. Swab it, mail it in, and receive a laboratory report identifying the mold detected in your sample. Identifies common indoor molds, including Aspergillus, Penicillium, and Stachybotrys.
For taking readings as you inspect. Detect moisture. Monitor humidity. Measure material moisture, indoor humidity, and temperature.
HomeSAFE is our sampling partner, and we earn a commission on kits and tools ordered through our links. Swab areas you can safely reach. Lab results show only what was sampled and aren't a diagnosis of your home.
We're professionals who work in the mold industry, and we built Mold HQ as an all-in-one educational guide based on our own experience.
We noticed that most sites promoting tests offered no explanation or guidance on how to use them or where to go from there. This guidebook covers the whole path: how mold grows, how to find the moisture behind it, what tests can and can't tell you, and what to do next, including when it's time to call a professional.
Mold is a normal part of the world around us. What matters is knowing where it shouldn't be growing, why, and what to do about it.
Every chapter, every checklist, and the seasonal routine that keeps the moisture out.
Get the guidebook · $10