Handling condensation problems in basements

It was a dank and steamy night. The house smelled acrid, and this time it wasn't my cooking. My cooking doesn't smell like mildewed running shoes, unless I fry cabbage, and I don't fry cabbage. So no, it wasn't my cooking. But the air smelled bad. Like a wet dog. Only I don't have a dog. The process of elimination was wearing me out. But I had to know where the odour was coming from.

I found myself in the basement. Not philosophically. Literally. The smell was worse there. I opened the door to the laundry room. The stink hit me like a short man in a bad suit. When I came to, I needed more than a stiff drink. I needed a dehumidifier.

See, I just moved in a week ago. It wasn't hot and humid when we bought the place, so it had smelled fine. But now the laundry room reeked like a barn full of cats with slack personal hygiene. It was my job to eliminate the stench.

I looked no further than the rotting carpet under the plumbing lines. Stained with old lime, that carpet had a look I hadn't seen since the 70's, and I didn't like the 70's.

I tugged on a corner of the carpet. Some bonehead had glued it to the subfloor. My evening was just getting better and better. Now I could use my brand new carpet knife. I made short work of ripping the carpet into strips and pulling it up. The plywood underneath was as damp and spongy as a damp sponge. It was so mushy I could have written my name in it. But I wasn't in the mood for calligraphy.

I looked around. Water was collecting in that basement like teenagers in a convenience store parking lot. The concrete walls and cold water pipes were covered in condensation, dripping steadily onto the floor. It was bad. I needed to know how bad. I whipped out my hygrometer. It was topping out at 68% relative humidity. The only time I've seen readings that high was in the summer of '89 in the back of a van. This basement was in trouble.

Prolonged dampness is a Sunday picnic for mildew, mould, and rot. In hot, humid weather, moisture condenses on the coldest surface available. It happens on beer bottles, and it happens in basements. But just slide one of those classy foam jackets onto a beer bottle and bingo, no more condensation. That gave me an idea.

I set up a fan to blow across the soggy plywood. The light breeze would drive off some of the moisture, but it wouldn't be nearly enough, not with 68% relative humidity.

I slipped out into the night and got into my truck. The engine kicked in like the startled rasp of an adolescent boy with adenoid trouble. I started to drive. I needed to think. Sure, I could insulate the pipes with those pre-formed foam sleeves they sell at the hardware store. But did I have to insulate every square inch of the cold walls and air-conditioning ducts too? Or was there some other way to stop moisture from condensing on the cold surfaces? And what about the sodden subfloor? Should I rip it out and replace it, or wait 'til it dried to see if it still stunk? And how was I going to get the subfloor dry in 68% humidity?

By the time I pulled into the hardware store parking lot, I was calm. I picked up a dehumidifier to decrease the basement's humidity. I got three lengths of foam sleeving for the plumbing pipes, and one gallon of Zinsser BIN stain-blocking Primer to seal the plywood subfloor once it dried. The primer would lock any stink in, and protect the plywood from growing more mildew. Then, as an afterthought, I went for an additional gallon of mildew-resistant porch and patio paint, because once they've invaded, mildew spores lurk like an evil warlord in a historical romance novel.

I drove home and wrapped the pipes with the self-sealing foam sleeves. Easier than putting doll clothes on a cat.

Next I plugged in the dehumidifier. It was humming contentedly when I closed the door to the laundry room and went to bed my favourite way: smiling. The next morning that dehumidifier had sucked a gallon of water out of the air and it was still pullling. I was a happy woman. But I knew there was one thing that could make me happier. So I connected a garden hose to the dehumidifier and ran it to the basement drain. Now I'll never have to check the dehumidifier reservoir again.

Just as I was thinking it doesn't get much better than this, it did. I whipped out my hygrometer again. Down to 36%. My heart beat a little faster. The plywood was dry now, so I vacuumed, cracked open the BIN Primer and sealed the whole floor. No more residual mouldy smell. No more condensation, anywhere.

Maybe some day humans will grow nose hairs fine enough to strain mildew spores out of the atmosphere. But until then, mildew is just botany gone horribly wrong. Let's fight this thing in the basements and in the bathrooms, until one day, old people will say, "Remember when we had that mildew problem?" And none of the youngsters will know what they're talking about.