[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: GSBN: Fire test

Lars, Joergen, and everyone.

Among the discussions that have been taking place off-list in relation to the seemingly widespread disdain for testing a cement-lime plastered bale wall, we have been considering the nature of exactly the question that Joergen raises - "I cannot help to wonder why 2 hours fire resistance is relevant to straw-buildings."

We fully recognize that for most of the builders and designers on this list, the projects they do don't require a fire rating. And so, other than the potential benefit that will likely result in gaining acceptance with insurance companies, and the ability to further reassure clients about the fire safety of bale structures, these two tests will be relatively insignificant for those doing primarily single family houses.

However, more and more of us in the US have been getting involved in larger projects for schools and other commercial or institutional buildings. These buildings almost always do have fire rating requirements and they are also more likely to require highly durable, lower maintenance wall finishes that can be reliably applied with fairly certain performance in terms of durability and cost. Thus the interest and need to have available test results for cement-lime plasters - which meet those particular characteristics with far greater regularity than either lime or earthen plasters in their current state of development and use in the US. This is not a knock on anyone - just an observation of mine that has been reinforced by conversations with numerous others who are struggling to get these systems to a point where they are commercially viable, cost-effective and reliable enough for the people who must take on the liability of doing these types of buildings.

The research carried out by John Straube, showing the remarkable increase in water vapor permeability of cement-lime stucco resulting from the addition of more lime has reduced some of the concerns about moisture management in these types of assemblies, as well. (See the research results on the Ecological Building Network website www.ecobuildnetwork.org). None of this denies or dismisses the issues surrounding the environmental impacts of portland cement including its contribution to global warming. This is just where we are in the current state of evolution of this building system. And it's worth noting that the climate impacts from the production of lime are not insignificant either.

It is worth noting that we've also heard from others who contend that the inclusion of a test of earthen plaster on straw bale has little practical value at this point in time. Their reasoning is that the buildings that could most benefit from this don't require a fire rating in the first place and the buildings that do need it are unlikely to be using earthen plaster for durability and maintenance reasons.

I confess that I was glad to see the widespread support for testing an earthen plastered wall for many of the reasons stated in all those messages to this list. But for me there is an even bigger reason behind testing an earthen plastered wall in addition to a cement-lime plastered wall. Here is part of my contribution to that discussion:

"The other factor that weighs heavily in favor of testing an earthen plaster wall is the same that motivated my initial efforts in trying to develop "appropriate" ASTM standards for earthen architecture, and which also motivates Bruce's current efforts in that realm, which is the degree to which US standards, codes, test results, etc. have weight and credibility elsewhere, especially in developing countries. Knowing how much trouble advocates around the world are having in gaining approval for any earthen building, or alternatives like straw bale, earthen plasters, etc., and how much acceptance in the US makes these things acceptable elsewhere, I think this test is important. It will also, assuming of course that it is successful, open the door for much more use of earthen plasters here in this country, including in some applications that may be fairly "boutique" in the large scheme of things at this point in time. And things are going to change pretty drastically at some not too distant point in time as petrol and climate realities become more and more evident and our options and ability to use whatever resource- and energy-intensive thing that we like become less and less viable. A lot of these things that are niche status today may become much more mainstream sooner than we imagine and it would be very good to have such test results to point to when things start to shift, rather than scrambling to find the resources (not to mention the natural gas to fire these walls) at that point...Anyway, that's my thinking on it."

Bruce chimed in with this: "I believe that IF an earth-plastered wall can pass the test (not by any means certain -- the fire's not the problem, but the hose test scares me), then we will have leapfrogged forward, so to speak. The benefit would accrue not just to the EarthFirst! crowd of baleheads, but in oblique ways bolster the acceptance of earthen construction in general -- something I very much want to do. And, as David said, we ain't gonna have cheap oil in the very near future, so let's take the long view and plan ahead."

So, for big reasons and current realities, we're aiming to satisfy both of these needs in the most careful and thoughtful way we can. We would love to be in the position to conduct many more tests and hopefully we will, but in the meantime, we're going to make sure we do whatever we can to get one and hopefully two successful 2-hour full scale fire tests done. That would lay to rest any questions about fire safety for almost any type of occupancy for which we envision bale walls being used. And this will cap the suite of tests that Ecological Building Network oversaw with funding from the State of California...all of which will be available in the book Bruce is working on as well as on his website.

As for comparisons between testing standards, I would love to see such a comparison, though there are a great many different tests and test methods for construction and construction materials. Perhaps there is already something along the lines of such a comparison as a result of the international standardization efforts. It would be a great thing to know about the similarities and differences between different countries' testing protocols. For instance, I have seen no mention in any of the discussion of other fire tests of the equivalent of a hose stream test. My guess is that the ASTM E-119 with hose stream test is the most demanding fire test protocol and if we can pass that test here it would be acceptable anywhere. Perhaps someone out there is in a position to begin compiling technical descriptions of the testing protocols from around the world... Anyone?

Soon we'll have a better idea of whether we've made wise decisions. The true test will be the tests themselves...
David Eisenberg

-----Original Message-----
From: Lars Keller larskeller@...
To: GSBN@...
Cc: jma@...
Sent: Sun, 7 May 2006 07:20:32 +0930
Subject: GSBN: Fire test

 The following is a request / suggestion which I am passing on on
behalf of Joergen Munch-Andersen, whom some of you might have met at
the ISBBC 04.
Joergen is Senior Researcher at the Danish Building Research Institute
(www.sbi.dk) and has for more than 5 years consistently been
constructively critical and he has made a huge difference towards
making SBC an accepted building method in Denmark.
Furthermore I should say that Joergen has on several occasions shown
that he is ready to put in time.

Best regards

---------- Forwarded message ----------
From: Jørgen Munch-Andersen jma@...
Date: Sat, 29 Apr 2006 17:32:14 +0200
Subject: SV: Brandtest i Californien.
To: larskeller@...

It would be most useful if somebody could compile a comparison between
American and European test methods and requirements. That would help
tremendously when trying to transfer tests and experiences.

In all of Europe the test methods are almost the same so the
CEN-standards can be used as a reference. On the other hand the
Building Regulations are quite different in the different countries.
But the test results can be transfered within Europe. Seen from this
side of the pond the comparison of test methods is the most important.

I cannot help to wonder why 2 hours fire resistance is relevant to
straw-buildings. In Europe that is only relevant for high rise
buildings. But if the test conditions are much different it could be
part of the explanation. One should remember that the time we refer to
is for a standard fire with a specified temperature as function of

A report on a Danish research project on SB - partly written in
English - can be downloaded as pdf from:
<a target="_blank" href="http://www.sbi.dk/byggeteknik/konstruktioner/serlige-konstruktioner/halmh";>http://www.sbi.dk/byggeteknik/konstruktioner/serlige-konstruktioner/halmh</a>

Slides in English from a presentation of the report:
<a  target="_blank" href="http://www.sbi.dk/download/pdf/jma_slides_halmhuse.pdf";>http://www.sbi.dk/download/pdf/jma_slides_halmhuse.pdf</a>

J&#xC3;&#xB8;rgen Munch-Andersen
Senior Researcher, PhD
Danish Building Research Institute (SBi)
Dr Neergaardsvej 15
DK-2970 H&#xC3;&#xB8;rsholm
Tel +45 4574 2388 (dir)
Fax +45 4586 7535
GSBN is an invitation-only forum of key individuals and representatives of regional straw construction organizations. The costs of operating this list are underwritten by The Last Straw Journal in exchange for use of the GSBN as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list, send email to GSBN@...HELP in the SUBJECT line. ----

GSBN is an invitation-only forum of key individuals and representatives of regional straw construction organizations. The costs of operating this list are underwritten by The Last Straw Journal in exchange for use of the GSBN as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list, send email to GSBN@...HELP in the SUBJECT line.