[Strawbale] Strawbale Digest, Vol 22, Issue 12

[Derek Roff]

--On Friday, April 18, 2008 12:00 PM -0500 
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> Today's Topics:
>
>    1. window construction (Dave Howorth)
>    2. Re: window construction (Robert Tom)
>
>
> -------------------------------------------------------------------
> ---
>
> Message: 1
> Date: Thu, 17 Apr 2008 22:11:58 +0100
> From: Dave Howorth <dave at howorth.org.uk>
> Subject: [Strawbale] window construction
> To: Strawbale REPP list <strawbale at listserv.repp.org>
> Message-ID: <1208466718.5922.320.camel at piglet.howorth.org.uk>
> Content-Type: text/plain
>
> Hello,
>
> I'm new to this list and have a couple of questions about window
> construction in straw bale walls. I'd be grateful for any pointers
> to resources that address these issues.
>
> My first question is about thermal bridges. All the drawings I've
> seen use a timber mount/buck/rough frame to connect the window to
> the wall. Doesn't this cause a thermal bridge? (especially if the
> window frame has been detailed with a thermal break) Are there any
> construction details that avoid this?
>
> My second question is about cutting openings in walls. I've seen a
> few mentions of cutting window openings after the wall has been
> built and plastered, but I haven't seen any detailed descriptions.
> So I'm left wondering such things as: do the openings have to
> follow bale boundaries or can they be made arbitrary sizes? If
> arbitrary, what stops the cut bales disintegrating? What linings,
> flashings, framings, plaster etc detailing is used?
>
> Thanks, Dave
>
>
>
> ------------------------------
>
> Message: 2
> Date: Thu, 17 Apr 2008 20:40:41 -0400
> From: "Robert Tom" <ArchiLogic at yahoo.ca>
> Subject: Re: [Strawbale] window construction
> To: "Dave Howorth" <dave at howorth.org.uk>
> Cc: SB Yahoos <sb-r-us at yahoogroups.com>, SB REPP
> 	<Strawbale at listserv.repp.org>
> Message-ID: <op.t9r6t4wg291bzk at edg-2wjjz8rsqjd>
> Content-Type: text/plain; format=flowed; delsp=yes;
> 	charset=iso-8859-15
>
> On Thu, 17 Apr 2008 17:11:58 -0400, Dave Howorth
> <dave at howorth.org.uk>   wrote:
>
>> My first question is about thermal bridges. All the drawings I've
>> seen use a timber mount/buck/rough frame to connect the window to
>> the wall. Doesn't this cause a thermal bridge? (especially if the
>> window frame has been detailed with a thermal break) Are there any
>> construction details that avoid this?
>>
>> My second question is about cutting openings in walls. I've seen a
>> few mentions of cutting window openings after the wall has been
>> built and plastered, but I haven't seen any detailed descriptions.
>> So I'm left wondering such things as: do the openings have to
>> follow bale boundaries or can they be made arbitrary sizes? If
>> arbitrary, what stops the cut bales disintegrating? What linings,
>> flashings, framings, plaster etc detailing is used?
>
> Dave;
>
> On the first point re: thermal bridges
>
> Yes, you're correct.
> A timber buck/rough frame can represent a thermal bridge but only
> if you   detail it as such.
>
> The means to avoid creating that thermal bridge would be the same
> as with   any other wall system and that is, as you imply, by
> including a thermal   break. The most obvious first step towards
> that end is simply to not   utilise a solid lumber, full wall-width
> buck and insulate.
>
> WRT the second question re: cutting door and window openings after
> first   plastering the bales, IMO that was simply an ill-conceived
> idea from the   get-go and would best be avoided. About the only
> point on the "plus" side   for the idea was that it was more
> expedient for building contractors... ie   get in and get out more
> quickly.
>
> On the negative side, IMO , firstly it demonstrates a disrespect
> for the   materials and the labour that went into making the
> cut-out section,   treating both as "commodities" and disposable at
> that.
>
> Second, it makes for a situation which is extremely difficult to
> flash and   seal in an effective fashion, which ultimately leads to
>
> performance-related problems and failures later on for the
> homeowner and   that, is disrespectful of the homeowner.
>
> Third, using an abrasive blade to cut through oftentimes
> metal-mesh-re-inforced Portland cement plaster creates an
> incredible   amount of gritty, permeates-everything, destructive
> (ie to motor bearings)   and harmful-to-respiratory-systems dust...
> and creates sparks that have   the potential to ignite any loose
> straw, or worse, drive hot molten metal   into the straw where it
> would go unnoticed and could cause smouldering   straw for a long
> time after.
>
> Fourth, pounding on a newly-plastered wall to knock out the cut-out
>  section is an excellent way to introduce cracks into otherwise
> good   plaster.
>
> As that Monty Python character once said in a cockney accent: "Need
> I say   more ?"
>
> --
> === * ===
> Rob Tom
> Kanata, Ontario, Canada
> < A r c h i L o g i c  at chaffY a h o o  dot  c a >
> manually winnow the chaff from my edress in your reply
>
>
>
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> End of Strawbale Digest, Vol 22, Issue 12
> *****************************************



Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek at unm.edu