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Zeno
Citizen
Username: Eratosthenes
Post Number: 28
Registered: 9-2003
| | Posted on Monday, February 16, 2004 - 10:25 pm: |     |
There appear to be many misconceptions about basement insulation. Having listened to just about every contractor say something wrong on the subject, I am starting to wonder if it is me.
I've heard many contractors tell me to put batts against the foundation wall, with a vapor barrier. Bad move, this is a recipe for a mold factory. See http://www.buildingscience.com/resources/foundations/default.htm
and read the article on basement insulation systems. I am only providing the most readily available reference. Basically warm moist air leaks through the insulation and condenses against the wall. The alternative is XPS against the wall, it will allow the moisture to permeate back so it is not trapped between the wall and insulation. Then gypsum or cement board as a thermal barrier.
The only insulation contractor whom I've spoken to that seems to know what he's talking about, advocated poly-encapsulated batts against the wall and claimed that a dehumidifier would solve the moisture problems. While I've heard of studies using this approach, this is making a lot of assumptions about the ability to dehumidify the basement. Is the news about mold in basements too recent for the pros to be up on it? Reports from Canada and Minnesota of disasters with traditional approaches are only 2 years old.
Then there is the issue of insulating the basement floor, in order to avoid condensation and mold. The white paper above suggests polyethylene sheeting, then rigid foam, then plywood subfloor. I've been told that it's sufficient to rely on the dehumidifier, which sounds good to me since the basement ceiling is low, but that poor old dehumidifier seems to be carrying quite a burden.
Anyone else have a (preferably informed) opinion?
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bobk
Supporter
Username: Bobk
Post Number: 4678
Registered: 5-2001
| | Posted on Tuesday, February 17, 2004 - 8:16 am: | |
I was channel surfing yesterday and caught an eposode of Bob Villa's Home Again. They were touting a basement finishing system made by either Owens Corning or Georgia Pacific (forget which) where prefab panels are used for the walls. All the parts of the panels were made with materials that don't support mold growth. Remember mold needs "food" to live. The panels are designed to breath and not trap moisture against the wall. This is a professional intalled product and the number of $40 per square foot of floor area was mentioned.
Let's face it. Basements in the typical 60 to 100 year old Maplewood homes were never designed to be finished living space. In the 50s people used knotty pine planking, usually with no insulation and that seemed to work. Using fibreglass and drywall is probably going to cause a problem sooner or later, no matter if you have French Drains or not. |
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