Can You Clean This Mold Yourself, or Is It Time to Call Someone?

By John Calhoun, owner of Mold Remediation Gettysburg PA · Updated October 20, 2026

“I’ve got a spray bottle and a Saturday. Can I just do this myself?” Often, yes. The EPA’s rule of thumb is that if the moldy area is less than about 10 square feet, roughly a 3 foot by 3 foot patch, most people can clean it up on their own. Past that size, or in a few specific situations, it’s a job for someone with containment and the right equipment. And whatever the size, the cleanup only sticks if the water that caused it gets fixed first.

The 10 square foot rule, and what it assumes

The 10 square foot line comes from the EPA’s home guide, and the Pennsylvania Department of Health says much the same thing: clean it yourself only if the area is under 10 square feet and nobody doing the work has health problems. Over that, the state’s fact sheet says to hire a contractor.

The rule quietly assumes three things:

1. The moisture source is fixed. Clean a spot under a leaking window and you’ll be cleaning it again in a month.
2. The mold is on the surface you can see. A patch on drywall can be the front of a much bigger patch on the back. More on that in mold behind drywall.
3. The material can be cleaned. Hard surfaces can. Moldy ceiling tiles and carpet, the EPA notes, may have to be thrown away. The sorting rules are in what to throw away after mold.

When it’s not a DIY job

For bigger jobs, the EPA’s guide for schools and commercial buildings sorts work into small (under 10 square feet), medium (10 to 100) and large (over 100), with containment and protective gear stepping up at each size. It’s written for those buildings, but the same logic applies to a house.

How to do a small cleanup right

• Gear up. The EPA lists an N-95 respirator, long gloves that reach the middle of your forearm, and goggles without vent holes.
• Scrub, don’t spray. Detergent and water on hard surfaces, then dry completely. The point is to remove the growth, not just wet it.
• No fans on visible mold. The EPA warns they can spread it. A dehumidifier placed away from the growth, not blowing toward it, is the better tool.
• Don’t paint over it. The CDC is direct about this: painting or caulking over mold will not keep it from growing.
• Bag what comes out before carrying it through the house.
• Watch it for a few weeks. If it comes back, the moisture isn’t fixed.

The common mistakes that make it bigger

The one I see most is waiting. A small spot doesn’t go away by itself, and a wet wall doesn’t stay small. The second is the shop vac. A regular vacuum blows fine dust right out the exhaust. The third is tearing out drywall without plastic, which carries the problem into every room the air reaches. That’s what plastic walls and air scrubbers are for.

In Gettysburg, a fourth one is ignoring the age of the house. Most borough homes are old enough that their paint can contain lead. If a DIY cleanup turns into cutting out painted drywall or plaster in an older house, read up on lead-safe practices first. More local numbers are on the Gettysburg housing data page.

A contractor’s tip before you start

Before you scrub anything, take a photo and press a gloved finger on the material around the spot. If it’s soft, cool or damp, the water is still active, and that’s the part to solve first. I’m John Calhoun, and I’ll tell you honestly when a job is small enough to handle yourself. If it isn’t, that’s what my mold remediation work is for, and the overview of mold remediation in Gettysburg, PA explains how I approach it.