[Greenbuilding] Radon
barbara deane-gillett
deaneg at hotmail.com
Mon Jul 16 00:50:51 EDT 2007
it has to do with how leaky the soil is under the slab. typical situations
requiire you to move 50 cfm or more to create the pressure field under the
slab, this is tough to do thru the 3 inch pipe. it can work in situations
where the underfloor is tighter like sand or clay rather than rock or
gravel. you can always use 2 or more 3" or smaller pipes to develop the flow
and spread the field around. althoughthis is more expensive in pipes and
pumping costs. it might make it easier to build in unobtrusively however.
the key area for friction loss is actually the entrance of the pipe to the
below floor area. this should be fairly open rock or air for about a cubic
foot. more details at epa.
sometimes sealing the slab and other holes reduces the air needed to create
an adequate pressure field.
suggest you take their or state courses if they are still giving them.
don't forget hrv's, submembrane and passive systems as alternatives although
subslab suction is usually the best and cheapest.
drew gillett, p.e. worked with terry brennan of camroden who developed the
field procedures 20 years ago.
______________________________________________________________
From: "RH Irving Co Inc." <rhirving at tds.net>
To: <greenbuilding at listserv.repp.org>
Subject: Re: [Greenbuilding] Radon
Date: Sun, 15 Jul 2007 18:05:25 -0400
>Anybody know why radon vents have to be 4"? A 3" pipe will fit thru a
>standard 2x4 wall; a 4" pipe requires a 2x6 wall (more lumber) and limits
>the possible locations.
>Bob Irving
>
>-----Original Message-----
>From: greenbuilding-bounces at listserv.repp.org
>[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Kidd, Peter
>Sent: Wednesday, July 04, 2007 10:44 AM
>To: Lawrence Lile
>Cc: greenbuilding at listserv.repp.org
>Subject: Re: [Greenbuilding] Radon
>
>CMHC brought out a new guide for Canadian homeowners, but its info is
>not really exclusive to Canada.
>www.cmhc-schl.gc.ca/odpub/pdf/61945.pdf
>
>
>-----Original Message-----
>From: greenbuilding-bounces at listserv.repp.org
>[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Lawrence
>Lile
>Sent: Tuesday, July 03, 2007 2:55 PM
>Cc: greenbuilding at listserv.repp.org
>Subject: [Greenbuilding] Radon
>
>
>I've recently had to go through radon testing in some rental houses, and
>learned a lot in the process.
>
>Radon relates to Green building because radon is an insidious indoor air
>pollutant. Tighter houses that began to be constructed in the 1970's
>began to concentrate indoor radon more than old leaky ones did.
>Awareness of this problem is not more than 30 years old, and really in
>the last ten years has it been even considered widely.
>
>Radon was discovered as a problem in homes when a nuclear plant worker
>inadvertently wore his radiation dose badge home. His house was hot!
>After the guys in moon suits, who figured he'd brought home some
>radioactive material fromt he plant, got done, they realized his house
>had a high level of naturally occurring radon, which is radioactive.
>Then they tested his neighbors house, and it was hot, and tests houses
>throughout the town, and a big fraction were hot, and within a few years
>realized there was a national problem.
>
>OK how big a problem? A smoker, who lives in a house with 20 pC/L of
>radon for many years, has a risk of 250 per 1000 of getting lung cancer.
>That's pretty bad! The risks go down for nonsmokers, and go down even
>more for lower levels of radon. 4 pC/L is the minimum action level,
>where lung cancer risks are not much different than where there is no
>radon.
>
>Any new construction *should* have at least a passive radon reduction
>system installed (so-called "radon-ready") and have a radon test after
>construction is complete. There are no laws or codes about this, but it
>is becoming common to see buyers requiring radon tests. It is a lot
>easier to build during construction than to retrofit. I would consider
>it a vital part of a Green home.
>
>We installed an active radon reduction system last weekend. It was
>actually quite simple - a pipe to the gravel under the slab, 4" PVC
>(shudder) pipe to a small, low power fan, and then an exhaust pipe to a
>bird screen up under the eaves. Slap on a label, and there you go.
>Contractors charge $1000 to $2000 for such a system, which uses about
>$200 in parts.
>
>I was surprised how much air was blowing out the top of the exhaust
>pipe. There must be quite a number of cracks under a typical older
>slab, to allow air to flow so freely. There is probably a big hole
>under the tub, and gaps at some plumbing penetrations, as well as cracks
>int he basement floor and around the edges.
>
>Lawrence Lile
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