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RE: GSBN:Compression using polyester strapping.



Hi Rikki,
I did not realize that I couldn't send attachments so thank you for that
new information. What a learning curve this whole internet process is
for me. After working as a conventional builder for over 30 years, I am
comfortable with building, but this email and internet stuff often
stretches me. 

I should clarify that the compression strapping we are using is not
plastic or polypropylene, but polyester. It is a woven strap 19mm (3/4")
wide with a breaking strain of 1,100 kg. It is inexpensive, less than
$200 for our average house of about 20 squares. (4 Bedroom 2 Bathroom 2
living areas) Why we need such big houses is beyond me, but that is what
most people in Australia want. It is very quick to fit and the
manufacturers tell me it has only one enemy, which is high alkaline
exposure. Consequently we ensure the strapping is completely encased in
earthen render prior to application of any lime.

A small car weighs about 1,000kg, so using this strapping is equivalent
to sitting a small car on top of the straw bale wall every 450mm (18")
to squash down the bales. This is why we are easily getting the 7%
compression.

As opposed to some other systems, we compress to a point of pressure
rather than to make the top boxing even. We could easily work to a set
height, as we have a connector buckle on each side of the straw bale
wall, however we do not feel that the final height of the wall is as
important as consistent bale wall compression. Having the consistent
compression virtually eliminates future settling and the likelihood of
cracking. It is easy to pack the top boxing post compression, whether it
be for infill or load bearing. When building a load bearing structure I
would be unhappy to have a 6mm (1/4") variation in the height of the top
boxing, as this would create an uneven roof line. As a conventional
builder, this would be considered unprofessional, and would inevitably
lead to dips in the line at the end of the rafters where the fascia and
guttering would be fitted, making water catchment a challenge.  

I will send the image of the connection of the frame structure to the
straw bale wall to your email address that you have supplied. If anyone
else would also like it please let me know.

Regards

Brian Hodge

Anvil Straw
Building Consultants

-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Rikki
Nitzkin
Sent: Wednesday, 28 February 2007 8:34 PM
To: 'GSBN'
Subject: RE: GSBN:Bale to frame connection and frame height for infill
construction


Hi Brian, 

This list does not allow us to attach images to the emails.

Could you please send me a copy of this drawing as well?  Between
differences in vocabulary and being a visual learner all these verbal
descriptions are hard for me (and I think those on the list who speak
English not so well) somewhat confusing.  An image is worth a thousand
words.

Thanks!

Rikki Nitzkin
Aul?s, Lleida, Espa?a
rikkinitzkin@...
(0034)657 33 51 62 
www.casasdepaja.com (Red de Construcci?n con Balas de Paja)
 

> -----Mensaje original-----
> De: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] En nombre de Brian Hodge

> - Anvill Enviado el: mi?rcoles, 28 de febrero de 2007 7:00
> Para: 'GSBN'
> Asunto: RE: GSBN:Bale to frame connection and frame height for infill
> construction
> 
> Hi Laura,
> 
> Thanks for your email regarding the height of the timber structure and

> frame to bale connection
> 
> With infill we need the ring beam to be higher than the finished 
> height of the straw bale wall so that the top boxing does not get in 
> the way of the connection of the rafters or trusses to the ring beam. 
> We can achieve 7% compression with the polyester strapping with good 
> tight bales, so if you establish the height of your straw bale wall 
> with the bales relaxed and then deduct 5% you will end up with the top

> of the posts and ring beam protruding above the top boxing on the 
> straw bale wall. The connection of the bales to the frame is done by 
> inserting noggings between the rafters over the top of the top boxing.

> These infill blocks would extend from the top boxing to the top of the

> rafter, which is secured to the top boxing with 3" nails. It can 
> either be fixed to the front of the top boxing or skew nailed to the 
> top of the top boxing. I have attached a copy of the drawing from my 
> book, which I trust will help to clarify my explanation.
> 
> Once the infill noggings are fixed in place, the roof sarking would be

> laid over the top of the rafters and a roof batten fixed directly over

> the top of the infill noggings. The sarking should extend beyond the 
> outer edge of the straw bale wall, so that any condensation can drop 
> clearly to the outside of the building. We would normally extend the 
> sarking to the gutter. By fitting the roof batten over the infill 
> block you will prevent vermin entering the roof cavity.
> 
> When rendering, we would cover the top boxing and exposed top of the 
> bale with render. The roof/ceiling insulation can then be positioned 
> so as to bridge the gap between the roof and wall top, so as to avoid 
> a thermal bridge.
> 
> I trust this helps, and look forward to hearing from you again 
> shortly.
> 
> Regards
> Brian
> 
> -----Original Message-----
> From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of Laura 
> Bartels
> Sent: Wednesday, 28 February 2007 6:46 AM
> To: GSBN
> Subject: Re: GSBN:Compression for infill
> 
> 
> I apologize to have begun these questions about compression and while 
> traveling the rest of the week, found I had no email service. You all 
> may have thought I just dropped off the face of the earth, but just 
> found myself in the snow dusted canyons of Utah while I did some work 
> there. Thank you all for responding. I have heard now of a variety of 
> systems, not all of which I have full details on, but it's starting to

> be an interesting collection. I do have a few q's... Brian, how do you

> deal with post height and connection with the compression using the 
> box beam approach? And John, in the method below for your rare infill 
> projects, are you compressing with your all thread approach? What does

> the compression method attach to?  S'ppose any other photos might 
> answer much. Catherine, if you do get Brian's book in for sale, would 
> you post a notice for us? Again, thanks all for your thoughts and any 
> follow up photos. Laura
> 
> John Glassford wrote:
> 
> > G ' day Bill and Rikki
> >
> > The hole at the top or gap is dealt with in two or more ways 
> > depending
> 
> > on the deisgn of the building.  In the case of the South Coat House 
> > the architect designed the walls to fit below double glazed windows 
> > on
> 
> > a rake.  This worked well except for the fact that we had to make 
> > sure
> 
> > we achieved an exact height all round of 2.405 metres.  We had a 
> > tolerance of 5mm.  The rods achieved this and we got a 100mm 
> > compression from a 7 bale high wall. We were also within 5 mm all 
> > round after compression.
> >
> > Nikki I will send you some photos off list which will help explain.
> >
> > The other way is to build the wall to 250mm below the height of the 
> > top plate on the in-fill and then pre-compress 100mm or whatever the

> > test wall showed prior to building, then you have a gap or hole at 
> > the
> 
> > top of 350mm which will take one bale usually forced in for a tight 
> > fit above the straw bale wall.  This method has worked well for us 
> > when we do in-fill which is rare, as we usually build load bearing 
> > homes.
> >
> > Kind regards
> > John Glassford
> > Huff 'n' Puff Constructions
> > <a  target="_blank" href="http://www.glassford.com.au/";>http://www.glassford.com.au/</a>
> > Mount Kilimanjaro Climb 28/8/07 <a  target="_blank" href="http://www.coolamonrotary.com/kili/";>http://www.coolamonrotary.com/kili/</a>
> > 61 2 6927 6027
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> >
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