As a longtime reader of FHB and of breaktime I have come across a lot of useful information. As a common Joe do-it-youselfer, I have done a lot of work for myself and friends but I know my limits. I now have a problem that I don’t know how to solve. A friend of mine has serious heath issues and is in the hospital and can not return home until the mold in the crawlspace is cleaned. His wife called a “specialist” and they came over and within an hour gave her a quote for a dehumidifier and a sealing the crawlspace. I did not like this, I would at least like to see air quality tests done to even verify there is a problem.
Long story short…He has a 100 year old house on a block foundation completely sealing the crawlspace. There is a half hearted attempt to seal this space with poly but as I crawled under the house there were some puddles on the plastic. Normally I would recommend sealing the entire area but there is a twist. The house is on the eastern shore of Maryland and sits at about 5′ above sea level. Once a year or so, the island is under about a foot of water. I don’t think you can pump out water fast enough to keep the bay out. What is the proper thing to do? I don’t think I will be doing the work, but I would like to guide them through this problem.
Replies
I would cover all the dirt with plastic. With more time and money I would pre-slope all the dirt, so the water can be drained or pumped out from underneath.
I would figure a way to spray bleach on all the moldy surfaces. I think my pressure washer could suck up the bleach and shoot it to most areas. The fumes from it will reach most areas.
On the south or west side, I would run a dark metal chimney from the underfloor area to past the roof. When the sun hits it, a natural convection would occur that would draw air from the underfloor craw space. Suction of air would create a negative air pressure that would keep mold spores from traveling from the underfloor to the living space.
I like the idea of sloping the crawl floor for drainage. There has to be ventilation and an easy way for the water to get out. I might think about pouring a slab on the floor and sealing it, and opening up the crawlspace with lots of vents. It would still need to be monitored and maybe bleached every time it floods.
If your friend is that sensitive to mold they may need to think about moving. Some people react to it more than others, and it sounds like it could be an ongoing problem. Sealing it would be very, very bad as it would help to contain the flood water. It needs air.
I was just reading the spray foam thread and also thought that they could spray the underneath of the finished floor with closed cell foam. That would seal the crawl air out of the house. Is the furnace and ductwork in the crawl? That could be a problem...Hopefully there isn't since it floods annually.
It sounds like you guys are leaning towards the way I was thinking. What I think is the way to go is open up the space allowing it to breath and seal the underside of the floor with foam. I would think that some sort of covering over the exposed rafters would be needed, but I can not decide if this is good. It may trap water in if flood waters get that high but it would add some protection against mold. The only problem I have with that is there is exposed pipes running under the floor, they would have to be protected from freezing somehow.
I agree with them moving part, he doesn't want any part of it. I will continue to suggest it to him.