Crawl Space and an old house


Old 11-18-02, 11:35 AM
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Question Crawl Space and an old house

I just mived to a 1950 rambler and it seems to have a strong musty smell specially when the furnace comes on. The home has a crawl space, exposed, and with a couple of vents on each side of the house. The area appears to be dry for the most part. Will the installation of vapor diffusion retarder take care of the musty smell? Also the furnace installed in 2001 has the ventillation through the bottom. Under the unti there is a floor penetration of about 2 ft deep with some water and mud inside.
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Old 11-18-02, 10:09 PM
Join Date: Aug 2000
Location: USA
Posts: 15,834
Musty smell when furnace comes on

Have the furnance cleaned and serviced and inspected for mold/mildew. There has obviously been some possible flooding of basement. This information should have been passed on to you before closing.

Make sure soil around home is sloped away from foundation to carry away excess water and that gutters and downspouts are clear and carry excess water away from the foundation. Raised beds next to the foundation can trap water and send it down the basement walls. You will not discover the source of your moisture problem until you have lived in the house through some heavy rains.

It is not clear where the furnace is located or what you mean by 'floor penetration' beneath the unit. If there is mud in the unit, then it had to be transported there by water.

It might be helpful to have your realtor call the previous owner to inquire about the situation.
Old 11-23-02, 08:02 AM
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If you have mold, you have moisture. You probably have it in the exterior walls if the house is insulated with FG. Mold can be deadly. The previous owner's may have sold because the house was making them sick. Not uncommon. Hard to prove.

Starting with any ducts in the crawl space, remove and replace if they are the plastic/fiber glass type. Check the foil covered FG insulation in the furnance. Mold can grow in the FG during the cooling season.

Crawl space. Attach a 4 mil plastic to the side of the bottom plate and let hang down and across the floor. Cover floor with two layers, CROSSED and overlaped about 6" Attach 4 mil radiant barrier (RB)( 48" wide) to the side of bottom plate, over plastic and to the floor. Seal off vents. Foam and seal cracks to out side. Floor MUST be well drained. This method will raise the temperature and reduce the humidity to a point where mold will not form. If the mold is extreme in the crawl space you may have to treat first with clorox solution.

Upstairs exterior walls. Remove drywall and fiber glass. Treat with clorox solution if mold is extreme and fan dry. Install a two layer radiant barrier insulation and then a 4 mil RB over the studs, like a vapor barrier. Since the RB does not cause condensation the mold will not grow and the RB vapor barrier sheet will keep out any residual mold spores. You should smell a big difference immediately. Your HVAC bills will be lower too. You can also add a RB to the top of your attic insulation. Energy costs can drop as much as 50% or more.

If you have duct work in the attic that is another source of mold. There is a special way to prevent it.

If you want more detailed info, let me know.

Thank you for considering my opinion.

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