I discovered a leak in the basement of a rental property Friday from an upper floor and the plumber came to check it out today, as soon as he could get to it. when I first saw the leak in the basement, I contacted all tenants on that side of the building to check for leaks everywhere and gave them notice that the plumber may need to come into their unit today. All tenants insisted that there was no leak in their unit. I did not go in, due to potential Covid exposure as it is spreading in my area. On Saturday, I get a call from a tenant just above the leak in another unit adjoining wall that he has mold in his bedroom closet floor on top of the floor. He said he pulled out a small chest of drawers he had in there and then saw it.

Plumber checks it out and finds a shower leaking on the other side of the wall from where his mold is, in another apt. He fixes the leak but told the tenants on both sides, to watch it to be sure the shower was the only leak issue. He did not see leaks anywhere else.

Plumber tells me that yes there is mold inside the closet on the floor in the one apt and he sees mold under the flooring in the other apt where the shower was leaking. He does not know how extensive it is but it appears to not be a small amount.

I am assuming that I need to let the moisture dry out, and be sure the leaking has stopped and then get someone in there to do what? I believe the floor underneath the lineoleum is original hardwood but do not remember for sure. This was 18 years ago that we bought the property and put in the lineoleum. We have a smoker in there for decades so I was not in a hurry to replace it before this. I am guessing I need to have all the lineoleum pulled up in there and then somehow remediate the floor above and below the molded area. There are no professional mold removal people in my area as this is a small town/rural area. Last time I had an issue with mold, it was just under 2 sheets of sheetrock after a tenant air conditioner leaked into the window sill. I hired someone who took off the sheetrock, cleaned it up behind and replaced it with new sheetrock. Even painted it to match. I have no idea what needs to be done to flooring that molds.

I want to make it safe but not spend a fortune. I have texted the person who did it before as he was excellent. No text back yet, so not sure he wants to tackle that.

Advice needed please. I can't do much myself these days, at my age and condition, but don't want to get ripped off by someone who says I need more done, than I need.

Thanks for any advice.

IMO there are two concerns:

1) Is the mold severe enough to have affected the structure. In other words, has it caused rot to the point where wood is weak. This is somewhat subjective, but the easiest way to check is to probe with a screwdriver. Just take the pointed metal end and poke at it. If it makes a hard "thud", you are ok. If it goes into the wood and you can pry out fibers, there is damage. Do this both from the topside and then check underneath for damage to the floor joists or beams...either in your crawlspace or the basement. If there is no severe damage in either areas, you can move on to #2. If there is damage, you must make a judgment call as far as how severe...does it need a new floor joist? Can you resupport it by "sistering" on new lumber?

2) Health concerns due to the mold. Not all molds are dangerous. You could have it tested by purchasing a mold test kit and sending it to a lab....depends on how careful you want to be or how "litigious" your tenants are. EMS labs is where we sent ours (I was a home inspector), but they only sell the swabs in boxes of 50...so maybe contact a home inspector if you want to do this. Probably would cost about $125-$150 to have it swabbed and get the results. The test will tell you what "genus" of mold it is. But if the area affected is under 10 square feet, experts say you can self-remediate. Buy some concrobium spray at Menards or Lowes or online, wear an N95 mask and some gloves, follow directions on the bottle, and clean it. Once clean, wait a month or so and re-check the area.

If it were me, I probably would not bother with testing the mold...I'd just clean it so long as it's a small area. If it's a big area, you may want to hire a pro. Cleaning large areas can be expensive, and even if you clean what you can see, there may be more hidden behind drywall or under flooring materials.

Also, if the flooring is carpet, you'll never get it out of the pad/cloth. May have to put new carpet in that one area.

Depending how closed in the space is this might be a job for MOM from Oder-B-Gone. They have packets that release chlorine into the smallest of areas and will kill the mold.

Only use it though after the water source has been absolutely stopped.

You did alright with the flooring choice you had if it lasted 18 years. I am happy at about the 10 year mark.

Opppps I meant to tell you Odor X.

I am NOT giving you advice, but:

Sometimes when the surfaces are wet with mold is the best time to use the "proper equipment", a combination wet/dry (operational at the same time) HEPA vacuum, to remove the mold.

If you wait until it is dry, then the mold spores can go airborne and contaminate your are the area.