SB: Re: Santa Fe style, breathability

["Bill Hunt" <billhunt@redrock.net>]

Hello Karin- I am copying this (which includes your response in its
entirety) to the CREST strawbale list.  You can post to the list by going to
http://solstice.crest.org/discuss.shtml, and subscribing to the strawbale
list.  A brief response follows.
Cheers- Bill

----- Original Message -----
From: "karin" <strawbale@xtra.co.nz>
To: "Bill Hunt" <billhunt@redrock.net>
Sent: Thursday, October 25, 2001 3:16 AM
Subject: Re: Santa Fe style, breathability


> Hi Bill,
>
> Nice to hear from you, but you are a little mis-informed.
>
> I trust you will be good enough to pass our comments on along with your
> own.
>
> Strawbale construction, as do all other forms of building, depends on
> good construction details and competant tradesman.
>
> I am not surprised there are problems in houses you have seen to date -
> we also have seen some very poorly constructed and finished buildings
> that will obviously not stand the test of time both here in NZ and in the
> USA. I am pleased to say none have been built by our Company.
>
> There are Builders & then there are people who consider themselves
> Builders! or worse still the do it yourself people, labourers with no
> building expertise at all. Next to buying a new car this is the biggest
> investment most people will make in their lives. They don't build their
> car why do they think they can build a house? - especially a straw house
> when there is very little good information freely available.
>
> Our Company takes the NZ Building Code Durability of 50 years very
> seriously and has taken every precaution possible to ensure moisture
> protection to our walls.
>
> Contrary to your observations we do not promote straw in our parapete
> walls they are in fact all faulse!! and all have a number of moisture
> barriers in place seperating them from walls below.
>
> I would also have to disagree with your opinion on breathability and
> would like to know if you have ever lived in a straw bale home.
>
> We live in a strawbale home, our first for @ 3 years, the second for 2
> years at the end of this month. This after 2 years of research & testing.
>
>
> I cannot comment on the test you refer to, but having lived in straw bale
> homes for @ 5 years I know there is a difference in the air exchange
> between a straw bale home and a timber frame & fibre insulated structure
> and it is noticeable, even to visitors. Cooking odours are not retained
> and the house does maintain a much fresher smell. You refer to a blower
> door test as not showing significant changes, as a stickler for the truth
> as we are, it obviously prooved some difference and there are huge
> variables between plaster products, paint finishes and even the straw
> which would alter these test results considerably.
>
> You will not require a moisture metre to tell you if you have wet walls -
> breathabale or not, as you suggest, you will certainly smell it as we
> found out while visiting America.
>
> I hope you will be fair enough to pass our thoughts on your comments on,
> and to allow people to make informed decisions for themselves. I do not
> know the "list" you refer to.
>
>
> Regards
>
>
> Karin Cameron.
>
>
>
>
>
>
> KARIN & ALAN CAMERON
>
> Straw Bale Construction Co
> PO Box 346
> WANAKA
>             "Builders of Superior Homes"
>                 www.strawbalenz.com
> Ph (03) 4437736 Fax (03) 4437706 Cell (025) 2893478
>
> ----------------------------------------------------

To respond briefly on these points: (need of overhangs, and breathability
helping indoor air quality):
Having worked on and researched SB since 1993,  I think that substantial
overhangs protecting the walls are prudent, especially in rainy climates.

While some plasters are more "breathable" than others, such as earthen and
lime plasters, and these allow the escape of water vapor,  I don't think
there is significant air exchange (measurable in air changes per hour, by
blower door tests) to improve indoor air quality.  Breathability of cement
stuccoed strawbale, synthetic stucco, and various paints would be further
reduced.

I suppose it is possible that air changes measured in days could improve
indoor air quality, and that is what can occur through SB walls.   Still, if
this were the case, I would think there would be more potential for water
vapor to be carried into the bales, as well as heat loss occuring with the
air changes.
Perhaps you have better data you could share if I am incorrect in these
perceptions.

I have seen a number of "experimental" strawbale buildings fail, or suffer
damage, and have heard several "black goo" nightmares on the list.  I tend
to be much more conservative about what designs are appropriate for SB these
days, compared to 5 or 6 years ago.  Hip roofs, generous overhangs,
wraparound porches, etc. make sense to me.  I suppose Santa Fe style can be
done well, but it strikes me as more difficult, and not the optimal design
for strawbale walls.   I see Santa Fe style buildings here of conventional
materials that have problems.

I live in an older wood and brick structure that has significant *wood* rot
problems from inadequate (6") overhangs and deteriorated gutters.   Even
some of the brick and much of the mortar is in need of repair in many areas
(about 60 years old). The extent of wood rot problems in older buildings,
and the extent of failure of stuccoed conventional walls in rainy and humid
climates, contribute to my caution with using SB.

Out of time for now :-).
Wishing you and your company all the best-
Bill




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