Re: [GBlist] Wall permeability

["Mike Rogers" <rogers.mike@verizon.net>]

I'd like to second David's comments, and made a few additions.

First, get a copy of Joe Lstiburek Builder's Guide for your climate.

*Some* vapor permeability in the walls is not only a good idea, but I'd say
essential for most construction.  If any water gets into the wall cavity,
you'd like a way for it to get out.  With good vapor barriers on two sides
of a wall assembly this becomes more difficult.  At the same time, you do
want to control vapor passing through the assembly, and more so as your
climate tends toward either very cold or hot & humid.  In general, you'll
want a vapor retarder on the warm side, and a semi permeable barrier on the
cold side to provide some dying potential.

In terms of  IAQ, however, I would much rather see attention paid to
minimize internal sources and to provide ventilation, in most cases this
means mechanical ventilation.  I believe this is a much better strategy then
relying on some vapor permeability of your building assemblies.  Vapor
diffusion is a slow transport mechanism when compared to air transport
(e.g., ventilation).  I wouldn't want to wait for internally generated
pollutants to diffuse through my walls.

And seconding Fred's and David's suggestion, there are many conferences
nationally were you can listen to the likes of Joe Lstiburek and John
Straub.  If Boston is too far away, I'm sure there is something much closer
to home.  (Also, Joe Lstiburek and Terry Brennan just finished a series of
HUD-sponsored, free, two-day workshops on building science and asthma in New
England.  These may be repeated in the future.)

Hope this helps.

Mike Rogers

----- Original Message -----
From: Sarah Holland/David Foley <hollandfoley@acadia.net>
To: Greenbuilding <greenbuilding@crest.org>
Sent: Wednesday, January 16, 2002 10:00 PM
Subject: Re: [GBlist] Wall permeability


on 01/16/2002 5:00 PM, FUnger@aol.com at FUnger@aol.com wrote:

> Kirsten,
>
> Come to the NESEA Conference at Tufts University in Boston, March 21 & 22.
> Attend the two sessions that John Straub presents at. You can't learn it
> better than he will teach it. Check out www.NESEA.org

Kirsten,

I'll second that.  Please do be careful in evaluating Baubiology, which is
so groovy that folks just WANT it to be true, even when it flies in the face
of what we know about physics.  I was once very seduced by the "Breathable
Wall" idea.  It can work, if you are very, very good at building science.
John Straube is that good - most of us aren't.  Joe Lstiburek, who has
written the Builder's Guide series, is also that good.  The best information
I found in Europe on a sensible approach to "Baubiology" was from Bjorn
Berge and Dag Roalkvam of Gaia Lista, an architecture firm near
Kristiansund, Norway, and from Varis Bolkalders, an architect in Stockholm.
The contact info for Varis is Varis Bolkalders, School of Architecture,
Department of Housing, Royal Institute of Technology, 100 44 Stockholm
SWEDEN, Phone +46-8-7908568, Fax +46-8-7908539.  The contact info for Dag
and Bjorn is Gaia Lista, Jøllestø, N-4560 Vanse NORWAY, Phone +47-38-397710,
Fax  +47-38-397711.  (My contact info is 6 years old, so I can't vouch for
its accuracy.)

- David Foley



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