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Green Building Discussion
Topic: Problems With Wet Ductwork
Discussion Participants:
- Darrin Thornton asks about wet ducts
- Hal Levin responds with the dangers of mold
- Bion Howard on duct properties
- Darrin Thornton has trouble with inspectors
- Martin stays away from duct systems
- Mark Kelley on duct performance
All postings are the opinion of the writer, and BuildingGreen can take no responsibility for their accuracy or appropriateness.
Darrin Thornton asks about wet ducts
From: DARRIN THORNTON
Sent: Monday, September 23, 1996 10:42 AM
Does anyone have info. on what happens to duct work after water soaked (during construction) and the poss.side effects of the quality of the air in the home. Is it unhealthy? if an infant is there anymore risk involved? I see a lot of this happening in construction nowdays after subfloor goes on it may rain and the ducts get quite a bit of water in them. I've asked the HVAC guys about it and they say it'll dry out. (maybe a couple of years) That's sloppy work. Thanks again,
Darrin Thornton @ Polysteel Alternative Building Systems, Inc. 664 Hillandale Circle Eagle Point, Oregon 97524 Fax 541-830-FORM (3676) EMAIL: epsform@cdsnet.net
Top of fileHal Levin responds with the dangers of mold
From: Hal Levin
Sent: Monday, September 23, 1996 7:47 PM
If the ducts have dust or other potential nutrients for microorganisms (mold, mildew) the water will provide the missing ingredient for the environment they need to thrive and reproduce. Thus, the duct work could become a source of spores, both viable and non-viable, that can adversely affect occupant health. Allergic and asthmatic individuals are at greatest risk. If the ducts dry out, the fungi will not thrive, but I have a hard time believe the dust and other particulate matter that accumulates in ductwork under a house in Oregon, at least the wetter parts of Oregon, even dry out to that point. The atmospheric humidity, the infiltration through the intentional pathways and the typical leakage into ductwork would like keep the particle adequately moistened to nurture fungal growth.
I am a native of Portland. I own a tee-shirt that shows a bear riding a bicycle in the rain, holding an umbrella. The tee-shirt says that last year 546 people feel off the bicycles in Oregan and drowned! Get those ducts clean and dry before the house is inhabited.
Hal Levin email: hlevin@cruzio.com 2548 Empire Grade, Santa Cruz, CA 95060 Tel. 408 425 3946 Fax 408 426 6522
Bion Howard on duct properties
From: Bion Howard
Sent: Monday, September 23, 1996 8:58 PM
As the Ghostbusters once said: "This looks incredibly bad..."
If it is duct-board (mineral fibrous insulation) you may have a problem since the dry-out time depending on time of year may be so long that organisms (whose propagules are very likely already in place) will find it quite a nice growth medium. All the criteria are met: temperature, food source, sufficient moisture. Even in sheet metal distribution systems, funky growth can take place if the surfaces are coated with dirt that becomes moistened and never fully dries out.
You might want to contact a group like NAIMA (North American Insulation Manufacturers Assn., Alexandria VA) for specifics on how to dry wetted fibrous ductwork / ductboard. I am not sure how one would go about this and still be able to inhabit the indoor space.
Perhaps David Saum of InfilTech in Virginia (DSaum@aol.com) might have some ideas. Also, you might try the US EPA Indoor Air Division of the Office of Air and Radiation, in Washington, DC. c/o Ms. Elisa Feldman. --------------------- Mr. Bion D. Howard bhoward2@sprynet.com (business) Building Environmental ZowWatt@aol.com (fall-back) Science & Technology Voice:(301)627-2780 FAX:(301)627-4735
Darrin Thornton has trouble with inspectors
From: DARRIN THORNTON
Sent: Monday, September 23, 1996 10:52 PM
I contacted the inspection agency (county) that passed such systems in the past(ones which were full of water, also duct board on the ground) and they of course try to pass the buck to the contractor saying their respons. I don't think so!!! If they are the so called building and safety dept. what are they doing?? very clear in this case, not anything. Thank you all for the info. I did use it for support in these cases. thanks again. Thanks again,
Darrin Thornton @ Polysteel Alternative Building Systems, Inc. 664 Hillandale Circle Eagle Point, Oregon 97524 Fax 541-830-FORM (3676) EMAIL: epsform@cdsnet.net
Martin stays away from duct systems
From: Martin
Sent: Tuesday, September 24, 1996 12:05 AM
I prefer not to use ducts! Zonal electric heat -- hydronic electric baseboards. Mold spores could possibly result, which would then be well distributed in the building. This is not a certainty, and for warm/hot air ducts probably no problem. Wet insulation may not recover, so a good inspection is warrented after wetting. Poorly insulated and sealed ducts are major problems, particularly when run outside the thermal envelope (crawl spaces or attics. Martin.
Mark Kelley on duct performance
From: mark kelley
Sent: Thursday, September 26, 1996 8:47 PM
I saw some of the responses you got from Hal and Bion, ome thing to keep in mind: the air from the heating syustem in the ducts will be very hot (if gas 150 F or so, heatpump 100 F), the former is of course high enough to kill most organisms, and both are high enough to remove moisture quickly. Drying of a small amount of moisture should take hours, pools at low points may take days. If it is galvanized metal duct, no reaction will occur and drying it out will remove the conditions for mold and bacteria growth. Fiberglass duct or form board will take longer to dry, but still will respond to the extremely low humidity of the hot air - even in Oregon.
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