[GSBN] SB Overhangs (was Big News!)
Graeme North
graeme at ecodesign.co.nz
Wed Sep 1 21:53:35 UTC 2010
There are many ways to give a strawbale wall primary weather
protection - the trick is to make sure that it happens, and this is
what a Standard can do. Rain screening of some sort is one wonderful
method.
What I despair of is designers who appear to think that they are
"getting away" with something (what?) by leaving good prudent primary
weather protection off their buildings.
I prefer to sleep on wet windy stormy nights.
Graeme
Graeme North Architects
49 Matthew Road
RD1
Warkworth
tel/fax +64 (0)9 4259305
graeme at ecodesign.co.nz
www.ecodesign.co.nz
On 1/09/2010, at 11:52 PM, Rikki Nitzkin wrote:
> Hi all,
>
> Maybe this code could include various Options since there are many
> ways to solve the problem.
>
> About protecting clay-plastered walls from wind-driven rain or un
> protected gable roof walls, there is always the option of a
> ventilated rain-screen. I have seen many different options made
> with wood in Denmark, and on some of Tom Rijven's buildings in
> france. The rain -screens can be simple, beautiful and permit clay
> plaster.
>
> By the way, are you all aware of the Loadbearing Dome and Vault
> building (with a Green Roof) Gernot Minke is working on in
> Slovakia? It should be quite spectacular, and could make a nice
> article for TLS. I am off to participate in the build next week.
> Check out fotos at: http://minke-strawbaledome.blogspot.com/
>
> baling on...
> Rikki
>
>
>
>
>
> El 26/08/2010, a las 13:03, martin oehlmann escribió:
>
>> Hello all,
>>
>> again compliments to all this great work which in essence should
>> make things easier by systemized solutions. If I read Andys
>> remarks on freedom of desgin we might be able to solve the paradox
>> of securing people from design failures and at the same time
>> stimulate ongoing experiments by a simple preamble for
>> codes: ."this or better".
>>
>> This would be an opening to convince building inspectors for
>> what's not be known yet, but definitly soon will be offered.
>> Without flexibility there is just little innovation. And it is the
>> "cemented aspect" of the building industry which spends a minimum
>> for innovation in comparison to other sectors.
>>
>> Best wishes from a rainy Brittany,
>>
>> Martin Oehlmann
>>
>>
>>
>>
>> ----- Original Message -----
>> From: Andy Horn
>> To: '(private, with public archives) Global Straw Building Network'
>> Sent: Wednesday, August 25, 2010 10:36 PM
>> Subject: Re: [GSBN] SB Overhangs (was Big News!)
>>
>> Hi Martin
>> I certainly don’t envy those trying to create a 1 size fits all
>> international building code that balances freedom of design and
>> place for innovation with the specifics of good building practice.
>> Anyhow to add some further food for thought.
>>
>> In answering questions about what to do with multi storey designs,
>> I always find history to be such a valuable tool when it comes to
>> looking at various design responses.
>> The vernacular architecture of Japan has evolved a very sensible
>> architectural style when it comes to protecting their thin little
>> earth plastered wattle and daub structures. Numerous numbers of
>> these structures still exist with some are many hundreds of years
>> old, with some being even 3 or 4 storeys high of earth plaster!!
>> The roofs are often but not always hipped, affording good
>> overhangs all around and in the case of multi storey buildings
>> each floor has its own min roof around it like skirts.…so shedding
>> the rain at each level. In the case of gabled wall ends, all the
>> openings have min roofs over them. Other times the clay wattle and
>> daub is given a basic plaster and then an external timber siding
>> rather than more plaster is used. Effectively parapet walls are
>> generally avoided so the roof always closes over the top of a
>> wall. Even their boundary walls, which are usually of more solid
>> packed earth and are typically earth plastered, all have mini
>> roofs over the tops of the walls ….usually 1 layer of beautiful
>> crafted fire clay tiles overhanging either side with a ridge cap
>> in the centre. Their plastered walls are also broken into panels
>> with expressed timber framing, so that the plaster surfaces are
>> broken down into manageable sizes that can be plastered to
>> absolute perfection and generally present much fewer problems with
>> cracking.
>>
>> I am not familiar with the extent or wording of the code, so I may
>> be speaking out of context but generally I would be worried about
>> being overly prescriptive about how one solves a
>> problem ....especially where officials can take a narrow
>> interpretation of a code and there may be ways and new products
>> that have not been thought of yet that may offer alternate
>> solutions? While I agree having roof overhangs is best practice
>> and I have not done otherwise, it may be wiser that one set about
>> defining what one is trying to do that a roof overhang is doing…
>> i.e. not letting water get in from the top being the most critical
>> clearly….. or is one trying to give the wall some degree of
>> protection from rain hitting it by using an overhang as well?
>> Because outright protection I don’t believe is practical or even
>> necessary. I think the degree or amount of overhang is more of a
>> regional thing that is even specific to the exact context of the
>> site of the building… the intensity of rain that is potentially
>> hitting a wall and the direction that it comes (rain does not
>> always come from above) are clearly important factors to try and
>> understand and respond to and will vary from place to place.
>>
>> Context will change things and how one designs in relation to the
>> context …..so I would imagine some of what the code needs to
>> address would be how design may respond differently in relation to
>> the amount of rain, wind direction, wind driven rain (if
>> applicable), rain intensity, when it rains in relation to how cold
>> or hot it is, so one understands how quickly or otherwise rain may
>> be able to dry out again. The position of ones overhangs and rain
>> buffers (pergolas, shade devices etc) and use of rain screens may
>> be of more importance depending on where and how big one
>> designing……the rain here in the Cape is typically winter rainfall
>> that is wind driven almost always coming from the North west….and
>> in some cases comes in horizontally especially along the coast. In
>> these cases one has to look at incorporating siding over the bales
>> and rain screens on the exposed sides to help shield the rain….and
>> in certain cases I will avoid using straw in the parts where it is
>> too at risk….so I rarely end up with a building with 100% of its
>> walls being in straw bale.
>>
>> Best
>> Andy Horn
>>
>> ECO DESIGN – Architects & Consulatants
>> 6th floor, 79 on Roeland, 79 Roeland St.
>> 8001, CAPE TOWN, SOUTH AFRICA
>> Tel: 07 21 462 1614, fax 07 21 461 3198
>> website: www.ecodesignarchitects.co.za
>>
>>
>> From: GSBN-bounces at greenbuilder.com [mailto:GSBN-
>> bounces at greenbuilder.com] On Behalf Of martin hammer
>> Sent: 25 August 2010 02:50 PM
>> To: (private, with public archives) Global Straw Building Network
>> Subject: Re: [GSBN] SB Overhangs (was Big News!)
>>
>> Hi Graeme,
>>
>> I’ll send you the SB code off list.
>>
>> Re: the overhangs, what do you do with multi-story or tall walls?
>> Do you have roof at typical first floor ceiling height in addition
>> to the upper roof?
>>
>> I will definitely consider putting such a table into the SB code.
>> I saw Bruce’s vote of agreement, and wonder if anyone else
>> strongly agrees or disagrees that overhangs be code-mandated for
>> strawbale.
>>
>> Overhangs are generally a very good idea for SB, and I consider
>> them “good practice” or “best practice”. I don’t know if they are
>> at the level of “minimum practice”, which is typically the
>> threshold of code language, although all of that is open to
>> considerable debate. Also in your table you account for wind as
>> a factor, but not rainfall. If your table were applied to desert
>> climates, it might be unfairly restrictive (although some desert
>> climates receive concentrated periods of rain).
>>
>> In an earlier iteration of the code I prohibited strawbale
>> parapets, but for a few reasons decided to instead be silent on
>> the issue.
>>
>> Martin
>>
>>
>> On 8/24/10 4:11 PM, "Graeme North" <graeme at ecodesign.co.nz> wrote:
>> HI Martin
>>
>> firstly my congratulations -
>>
>> and yes, I would really appreciate a word document I can make
>> comment on
>>
>> >From my neck of the woods, one of the overriding issues I
>> encounter time and time again is that of good weather protection
>> from wind driven rain in our decidedly pluvian and humid climate -
>> something that gets skittered around in most books and references.
>>
>> I think we need a prescriptive starting point. In the NZ Earth
>> Building Standards NZS 4299 we relate wind zone. eaves height
>> (vertical exposed wall height), and roof overhang width to give
>> MIMIMUM roof overhangs as follows -
>>
>>
>> Wind Zone - Ratio of eave height to width
>> Low (at ULS 32m/s) 4:1 (600mm over a 2400 wall)
>> Medium (37m/s) 8:3
>> High (44 m/s) 3:2
>> Very High (50 m/s) 1:1 (or in other words a full verandah)
>>
>>
>> We developed this table after leaks and some degradation of
>> material in some earthen structures and I can report that there
>> has been no reported problem since we adopted this.
>>
>> It is my contention that straw buildings are at least as moisture
>> sensitive as earthen buildings and I would suggest that this sort
>> of table be regarded a good starting point for calculating minimum
>> roof overhangs for direct-plastered external strawbale walls, a
>> recommendation that could possibly be worked back (or exceeded)
>> after local weather or site assessment, or possibly a service
>> history of locally developed techniques.
>>
>> It may seem a but draconian to some but for my money the biggest
>> problem with strawbale buildings, in humid wet climates at least,
>> seems to be that of providing adequate primary weather protection,
>> in the form of eaves, or rain screening, and lack of good
>> practical prescriptive guidance on this subject.
>>
>>
>> Comments welcome
>>
>>
>>
>>
>>
>> Graeme (in bossy standards writing mode) North
>>
>> Graeme North Architects
>> 49 Matthew Road
>> RD1
>> Warkworth
>> tel/fax +64 (0)9 4259305
>>
>> graeme at ecodesign.co.nz
>> www.ecodesign.co.nz
>>
>>
>>
>> On 23/08/2010, at 5:32 PM, martin hammer wrote:
>> Everyone,
>>
>> Lars Keller asked the below question so I thought I would answer
>> to all in case others are interested. I’ll set a deadline of
>> September 30th for anyone wanting to comment on the strawbale code
>> as in the second draft of the IGCC.
>>
>> Thanks.
>>
>> Martin
>>
>>
>> On 8/22/10 9:36 PM, "Lars Keller" <larskeller at gmail.com> wrote:
>>
>>
>> Dear Martin,
>> What is the deadline for comments to you ?
>> Best regards,
>> Lars Keller
>>
>> On 22 August 2010 03:36, martin hammer <mfhammer at pacbell.net> wrote:
>>
>> Hello friends on the GSBN,
>>
>> My voice has been conspicuously absent on this subject, so I
>> thought I would weigh in.
>>
>> First, thanks for the words of appreciation. I was pleasantly
>> surprised to hear the news from David on Monday. I think this
>> strawbale code document is very good, but there are a number of
>> reasons I didn’t think it would go through to the next step. I
>> thought both the Earthen Materials proposal (referencing the
>> recently revised ASTM standard that Bruce, David in earlier years,
>> and others worked so hard on) and the Straw-Clay proposal I co-
>> authored with Paula Baker-Laporte, had better chances. I might
>> propose them again in the upcoming Code Change Proposal phase
>> (once IGCC committee concerns are addressed).
>>
>> Much blood, sweat, and a few tears have gone into this SB code
>> since 2003, when I began writing it at the request of the State of
>> California (they asked Bruce, Bruce asked me . . .). I’ve had
>> very good input from others along the way, including members of
>> this list (David Eisenberg, Bruce King, Dan Smith, Bob Theis, Tim
>> Kennedy, John Swearingen, Bill Steen, Kelly Lerner) (apology if
>> I’ve missed anyone), and others not on this list, notably civil
>> engineering professor Mark Aschheim.
>>
>> Because it started as a California code, and because there are
>> great SB experts in northern CA where I live, the code might be a
>> bit California-centric (with particular attention to seismic
>> issues). However I’ve always wanted it to be broadly applicable
>> and I welcome broader, global input at this time. I expect to
>> propose adjustments during the next IGCC review phase. If it
>> remains in the IGCC and goes the way codes often do, some version
>> of this might show up at your building official’s door and then
>> your strawbale door in Australia, South Africa, or who knows
>> where. And although I think there’s much to like, I can almost
>> guarantee you can find something you don’t like. So . . .
>>
>> If you want to see and comment on the proposed code you can ask
>> me to e-mail the proposed SB code (by itself) to you as a word
>> document, and then e-mail me your comments or send it back with
>> “track changes”. OR you can go to: http://www.iccsafe.org/CS/
>> IGCC/Pages/Comments0810.aspx , and download all Public Comments
>> under the “Complete Document” subheading (Strawbale Construction
>> is Comment #5-136). You can then e-mail your comments to me (not
>> to ICC). I’m also open to comments on #5-134 Straw-Clay, and
>> #5-135 Earthen Materials. If you want to understand the IGCC
>> process and schedule, you can go to:http://www.iccsafe.org/cs/IGCC/
>> Pages/PublicVersionDevelopment.aspx
>>
>> In addition, I want to clarify that:
>>
>>
>> Strawbale is not yet in the IGCC. That’s because it isn’t
>> finalized (and SB could even be entirely removed).
>> Even if included in the final version, the IGCC applies only to
>> commercial and high-rise residential, AND only in jurisdictions
>> that adopt the IGCC. So it would have limited application.
>>
>>
>> That said, this approval is still a very good thing. And if it
>> does make it to the finish line of the IGCC, it would probably
>> then migrate to the IBC in the next code cycle, and then to a
>> jurisdiction near you. I even see the possibility of
>> jurisdictions adopting it or informally using it for all
>> occupancies, even before reaching the IBC. John Swearingen’s
>> report of it already producing “instant results” for his project
>> in Stanislaus County supports that notion, and is both welcome and
>> frightening.
>>
>> Finally, I want to acknowledge David Eisenberg and Matts Myhrman
>> who together forged the first SB code in Arizona in the early-mid
>> 1990’s, and to David again for speaking so convincingly on behalf
>> of the current proposed code at the recent hearing in Chicago. If
>> you read his description of what he said, you’ll see that he
>> simply told the compelling truth about the most relevant issues.
>> It’s one of many things David does so well. It’s nice when the
>> compelling truth prevails (at least for now).
>>
>> Thanks David, and thanks to all. And thanks to the enduring
>> spirit of strawbale!
>>
>> Martin
>>
>> PS - For a pre-IGCC history of this SB code, see my GSBN post on
>> Dec. 1, 2009. Reviewing that e-mail might also be used as a
>> natural aid to help you fall asleep. However, for me it is a
>> riveting drama (sometimes moving at the pace of a melting
>> glacier . . . actually that’s happening quite quickly these days!)
>>
>>
>>
>>
>> On 8/16/10 10:13 PM, "strawnet at aol.com" <strawnet at aol.com> wrote:
>>
>>
>> Hello all,
>>
>> I want share some great news. Earlier today, here in Chicago,
>> Martin Hammer's "comment"/proposal to include the strawbale code
>> he’s been working on over the past few years in California into
>> the new International Green Construction Code (IgCC) was approved
>> by a committee vote of 8 to 6! The IgCC is the new US code for
>> commercial (and high-rise residential) buildings that will become
>> part of the family of 2012 International Codes (I-codes). It will
>> go through a full code development cycIe with the rest of the 2012
>> I-codes next year and there is work that will need to be done
>> still to make sure it doesn’t get rejected in that process, but
>> getting it into the second public draft of the code now is a very
>> big step forward.
>>
>> I served on the drafting committee for this code from last summer
>> through the spring of this year. For more information about the
>> IgCC and to download the whole IgCC first public draft and the
>> comments – including Martin’s proposals for strawbale and earthen
>> building and the EcoNest comment in support of straw clay go here:
>> http://www.iccsafe.org/cs/IGCC/Pages/default.aspx
>> http://www.iccsafe.org/CS/IGCC/Pages/Comments0810.aspx
>> You’ll find these listed as comments 5-134, 5-135 and 5-136.
>>
>> I was the only proponent speaking in favor of it here, and there
>> were others who spoke in opposition. The initial motion was to
>> disapprove but it failed 5 votes to 9 after considerable and very
>> mixed discussion – which surprised me because of the nature of
>> some of the comments – that it was still not ready and needed some
>> technical fixes.
>>
>> The failure of the motion to disapprove required a new motion and
>> Chris Mathis, an old building science friend from North Carolina,
>> offered a motion for approval. That was followed by more
>> discussion, with more concerns expressed that it wasn't ready.
>> Then, just before the second vote, Chris pressed the committee to
>> push the envelope. He said they should approve it and get it in,
>> and rather than just having the few people who are very
>> knowledgeable about it work on improving the things that still
>> need to be done, “Let thousands of people look at it and help
>> improve it through the next round of the code development
>> process!” He said it was time to start pushing these things
>> through. Then they voted - and it passed 8 to 6! I was amazed and
>> delighted! So it is going into the second public draft!
>>
>> There were two other similar proposals (they’re called
>> “comments”) that were heard right before the strawbale comment.
>> The first, from Paula Baker Laport and Robert Laport proposed
>> including the straw clay guidelines fromNew Mexico. Next was the
>> other submitted by Martin, that one in support of earthen
>> construction based on the new ASTM standard for earthen wall
>> systems that I had initiated almost 10 years ago and Bruce King
>> has spearheaded over the past few years. I spoke in support of
>> both, but they were disapproved, though both received encouraging
>> suggestions to bring them forward again after addressing non-
>> mandatory/permissive language and other issues.
>>
>> Because they were heard one after the other, and I was the only
>> proponent for them, I got to speak first for each one and so I had
>> a total of 6 minutes (2 minutes each) to frame them all in terms
>> of the big issues I’ve been speaking to for all these years,
>> including the coming challenges of ever-more limited and expensive
>> energy, the low-impact, low-tech, climate beneficial, local/
>> regional benefits, the industrial/proprietary bias and difficulty
>> in funding research, testing and development for public domain,
>> non-proprietary materials and systems. I started off by talking
>> about the fact that I had been in buildings in Europe built with
>> materials like straw clay and earth that are twice as old as this
>> country! And to say that these are durable and safe ways of
>> building when done properly. And when talking about the ASTM
>> earthen standard, I said that if they looked at it they might
>> think that it was too low tech to be reasonable compared to the
>> standards that they’re used to for concrete and other industrial
>> materials. But, I said, It was intentionally low tech. That I was
>> involved in initiating that standard almost ten years ago and it
>> was both to enable the use of those materials here and to reverse
>> the outlawing of earthen building in developing countries through
>> the adoption of modern industrial codes. That it was designed to
>> enable people to build safe, durable, healthy, and affordable
>> buildings anywhere in the world—including the in United States. I
>> mentioned that the committee that developed that standard included
>> the leading experts on earthen building and engineering from
>> around the world and was based on reviewing and incorporating the
>> best from international codes and standards for earthen building.
>>
>> After the first two went down, I was quite convinced because of
>> the comments that the sb proposal would share the same fate and,
>> thankfully, I was wrong!
>>
>> So hats off to Martin, Bruce, Matts, and many others who have
>> worked so long and hard to develop these codes and to Chris Mathis
>> for his leadership and visionary action on the committee.
>>
>> Onward!
>>
>> David Eisenberg
>>
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