Crawlspace and basement, plan of attack?


Old 12-30-08, 11:49 PM
Thread Starter
Join Date: Jul 2008
Location: Toronto, Ontario, Canada
Posts: 32
Crawlspace and basement, plan of attack?

So last week i had an energy audit performed on my house. What an eye opener!

The the point of this post, i have a 100 year old house, with a concrete poured foundation and basement walls, with the kitchen being an addition to the back of the house, with cinderblock foundation 2 feet above earth floor. A hole has been knocked out of the original poured conrete basement wall so that a heating vent could pass through into the crawl space.

I plan on adding vaport barrier from top of crawlspace down and covering the earth floor, and then insulating the walls, to create a conditioned space underneath my kitchen floors.

Now, for the part im confused as to what to do. My basement floors are painted, i dont think they are actually sealed with anything. Ive read that concrete floors are no better than an earth floor at preventing the passing of moisture.

The inspector doing the audit recommended that i insulate the basement walls, but would this include covering the floor with a vapor barrier and then some sort of flooring over it?

as well, i should i seal the hole in the conrete basement wall to the crawlspace? If i did this i couldnt really create a seal with the vapor barrier.
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Old 12-31-08, 08:47 AM
Join Date: May 2008
Location: Connecticut
Posts: 124
"The inspector doing the audit recommended that i insulate the basement walls, but would this include covering the floor with a vapor barrier and then some sort of flooring over it?"

If you are going to insulate the basement, it is important that you control moisture, and as you've learned, concrete is usually no better than dirt when it comes to allowing moisture to seep through.

You may consider having the basement floor lined with an all in one basement flooring solution like ThermalDry or MillCreek. They are 100% waterproof and mold resistant floating, interlocking tiles or laminates that can be placed directly over concrete and offer both moisture and thermal protection, plus a finished look.The finished surface of the tiles is raised a few millimeters from the floor by a channel system that allows the concrete to breathe and the moisture to dry out rather than being trapped behind a conventional VB.

A vapor barrier will also be needed on the walls to keep the insulation from soaking up the water that seeps in through capillary action. Wet insulation loses most of its R-Value. If you don't have a drain tile system you might want to consider one to channel and divert the moisture collected behind the VB to a sump pump.
Another option would be a baseboard drainage system.

As for the hole in the basement leading to the crawl space: I am assuming it is no longer used, since you consider closing it.
If that is the case, I think it might be a good idea, since you are about to encapsulate and condition your crawl space.However I can't be 100% sure without seeing it. What does the energy auditor have to say about it? Maybe you should give him a call and ask for a specific recommendation on the matter.

Please be extra cautious if you have any type of combustion appliance running in that crawl space. You don't want to depressurize a crawl space with one of these inside.
Don't tackle this if you are not 100%, positively, absolutely sure of what you are doing.

Lining a crawls space with a VB seems simple enough, but trust me, if done improperly, not only it won't solve the problems it was supposed to (energy loss, moisture), as it will create additional ones (pests, mold, hazardous conditions).

It might make more sense to get a professional opinion on the case. Many companies offer free evaluation, so you won't lose anything by let them advise you on the best options.

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