Sealed Crawlspace A Mold Factory

Q: I am considering plugging the holes into my crawlspace to keep the cold drafts out and hopefully reduce my heating bills. I think this would reduce the chance of frozen pipes, too. Is this a good idea?

A: Never plug your crawlspace vents!

It is a common misconception that closing vents in the winter is a wise idea. This idea has its roots in climates where air is extremely cold for long periods of time. Very cold air by its very nature contains little moisture. What other moisture is around is frozen. This does not apply to our sloppy maritime environs where the battle against moisture is a year-round undertaking.

Quite often people mistakenly plug their vents and almost as often they end up with a real-life mold lab under their home.

The worst case I have seen in this regard was a well-meaning guy who diligently insulated his foundation walls, plugged his vents with foil-backed insulation (vapor barrier facing the cold side, thus trapping moisture) and spread foam sheets over the ground "for extra insulating capacity." The dryer vent became disconnected sometime in the interim two years.

He wondered why his home smelled stale inside.

I wondered how the house was still standing after all the wood rot that had occurred.

Wrap your fresh-water pipes with foam pipe insulation. If you are really worried about freezing, use heat tape in the exposed spots.

Insulate the subfloor, not the dirt floor. This makes the conditioned space (heated area) smaller. Ventilate the cold side of the insulation (the existing crawlspace vents) to eliminate moisture.

Q: My 10-year-old home has a half-inch to an inch of water in a section of the crawlspace, mostly under the vapor barrier, with some seeping on top. It is well ventilated and the wood seems fine. Do I have a problem that needs correcting? Other houses I've seen do not seem to have this problem. Who's in the best position to advise me?

A: If the water was throughout your crawlspace and there continually, yes, you would have a problem that needs correcting. If it occurs only after a 40-day flood (that's every December and January here) and goes away after a week, I wouldn't get my curlers in a bunch over it. You can usually find a cause for minor leaks and fix them fairly easily, many times by yourself.

In theory, you shouldn't have any water in your crawlspace. In reality, most do at some point.

Fighting water in a crawlspace or basement can be confusing. Ask 10 different contractors and get 10 different remedies on 10 different budgets.

Without professional help, you can check to make sure your downspout water is piped or channeled away from the building and the ground is properly sloped away.

Many times penetrations through the foundation wall for plumbing pipes aren't sealed around the pipe and water gets in when the water table rises. Seal these with patching cement.

Another common leak spot is at the junction of the foundation footing and wall. Clean the debris off with a wire brush and use wet patch cement (this is great stuff) to stop it up even while water is leaching through.

Beyond these basics, if you need help with footing drains, foundation waterproofing systems, downspout drains, interior systems, sumps and so forth you could have waterproofing, drainage, or general contractors consult and do the work. If you would like someone to advise you, an engineer, home inspector or perhaps your cousin Ernie could do that.

Q: I have a fiberglass soaking tub that has three or four cracks. How do I get it repaired? I have tried several tub repair services in the phone book and they do not seem to return my calls.

A: Try fiberglass repair or boat repair. You didn't mention how old the tub is, where the cracks are, how it is installed, or if the cracks go all the way through. If there was no blunt trauma to the tub, it is possible it was installed out of square and has some stresses that may or may not have been completely relieved by the cracking. Patching the cracks may be only a temporary solution if the tub was not installed properly.

Ask The Expert answers readers' questions every Saturday. Send questions to Ask The Expert, Seattle Times, P.O. Box 70, Seattle, WA 98111, or call 206-464-8514 to leave your questions on Ask The Expert's recorded line. E-mail address is dhay@seattletimes.com

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