Excessive moisture in home!

[homecritiquepi]

Hey gang, long time reader, first time posting! I have a pier and beam home customer that is getting excessive moisture in his home in the winter and other times a/c is not helping. He uses a meter to see that there is always more moisture in home than outside and the source is elusive. I inspected it several years ago without any issues found in regards to this: HVAC gas furnace is properly vented, has combustion air ducts and sealed closet, water heater and dryer are in adjacent but not connected garage. Crawl space is uneventful; dry and no signs of water leakage. He has been using a dehumidifier to lower moisture and there will be 20% outdoors, while over 50% indoors, he uses the dehumidifier and pulls it down and then it will climb right back up without using the HVAC at all. SO, what to look for? Thanks in advance!

[Jim Katen]

Is there a vapor barrier covering the soil in the crawlspace?

- Jim Katen, Oregon

[homecritiquepi]

No vapor barrier here, and I've never seen one in Central Texas before! So I don't guess we need one? The crawl space is vented on 2 sides only. The owner has a gas stove and the gas water heater is in the garage open to garage and to the attic above the garage and home. Water heater is properly vented and it's draft was observed (felt) at the draft hood and above roof. Flooring below bathroom and kitchen areas are dry. Weird!

[Marc]

Tell me about that meter that says the humidity is too high.

Marc

[hausdok]

Put down a vapor barrier. Even in dry climates a 1,000 sf house can evaporate up to 11 gallons of air into the atmosphere every 24 hours. Vapor diffusion will push that moisture directly up into the home.

OT - OF!!!

M.

[Jim Katen]

Put down a vapor barrier. Even in dry climates a 1,000 sf house can evaporate up to 11 gallons of air into the atmosphere every 24 hours. Vapor diffusion will push that moisture directly up into the home.

I agree with Mike. Start with a vapor barrier under the crawlspace. Right now, you look under there and the soil is dry. Put a vapor barrier on top of the soil and a few days later, if you look under the vapor barrier, the soil will be wet. It will be that way because it's no longer evaporating the water into the air.

There are probably other problems as well, but start with the crawlspace.

- Jim Katen, Oregon

[homecritiquepi]

Sounds good guys, a vaport barrier seems very logical, just not used to seeing them. I appreciate the input!

The moisture meter was an electronic dual sensor device, one inside and one outside, wirelessly connected.

Thanks again!

Glen

[Marc]

Are there any indicators of elevated humidity besides the meter, such as condensation? What problems are present?

Marc

[homecritiquepi]

Yes, home smells musty and the bottom of a futon has black mildew on it.

[Marc]

You said that the crawlspace is vented on only two sides. I'll take that to mean that those two sides have only one or two small vents in them instead of being entirely open.

I'm with Mike O and Jim K then. Either install the vapor barrier or provide adequate venting of the crawlspace.

Marc