[Cob] cob greenhouse question

[john fordice]

Hi Malcom,
Yes, the freestanding ends of your walls and midpoint of the long back wall should still be buttressed.  I’d suggest putting the buttresses on the outside surface of the walls & thus leave the rtransparent greenhouse walls fully open to sunlight.  
Small p[eces of urbanite should be ok, just don’t make them any bigger than 2 - 3 “.
john 
> On Sep 23, 2015, at 3:14 PM, Malcolm Schluenderfritz <mschluenderfritz at gmail.com> wrote:
> 
> Hello John,
> 
> I modified the design. Now the tallest cob wall will be 6 feet. Do I still need buttresses? 
> 
> I will leave out the urbanite chunks then. Would small pieces of rubble less then two inches across be OK? I was wondering if they would act like large gravel.
> 
> Thanks for your help.
> 
> Malcolm
> 
> On Sat, Sep 19, 2015 at 10:18 PM, john fordice <otherfish at comcast.net <mailto:otherfish at comcast.net>> wrote:
> Malcome,
> A few suggestions relating to the cob:
> 1. Buttress the open ends of your rear & left end walls.  Make the buttress’s 3 or 4’ long at the stem wall & zero at the wall top.  Add an intermediate buttress at the midpoint of the rear wall.
> 2. Batter your walls to 12” thick at the top & 18” at the stem wall.
> 3. Do not put pieces of urbanite in the cob …… bad practice !
> 
> This is relative to the cob only ……… the framing of the transparent materials support is another story …… sounds like the loads of the wood & plastic roof / walls will be minimal, so as long as you don’t have heavy concentrated loads either embed your rafters in the cob or add a top plate with deadmen in the wall.   Assuming you know how to make competent cob & build correctly ……… if not, get advice of an experienced cobber.
> john
> 
> > On Sep 19, 2015, at 9:51 AM, Malcolm Schluenderfritz <mschluenderfritz at gmail.com <mailto:mschluenderfritz at gmail.com>> wrote:
> >
> > ---------- Forwarded message ----------
> > From: Malcolm Schluenderfritz <mschluenderfritz at gmail.com <mailto:mschluenderfritz at gmail.com>>
> > Date: Fri, Sep 18, 2015 at 8:40 PM
> > Subject: Re: [Cob] cob greenhouse question
> > To: Howard Switzer <howard at earthandstraw.com <mailto:howard at earthandstraw.com>>
> >
> >
> > Hello Howard,
> >
> > Thanks for the advice.
> >
> > I will try to post a plan soon.
> >
> > I am stuck with the 18" base because the foundation is already build. I
> > agree that it seems something is needed at the North East corner.
> >
> > The concrete is to use it up and to speed drying on the wall. (An idea from
> > "The Hand Sculpted House." ) I got huge loads of broken concrete dumped for
> > the foundation and for retaining walls on other parts of the site. These
> > are pieces that are fairly good but not quite square enough for those uses.
> > Spaced widely (so that they do not form problematic joints) in the core of
> > the wall, it seems that they will allow me to use less cob, which not only
> > means faster drying, but also less cob mixing and less purchased sand use.
> >
> > I would think that if cob is strong enough to arch over small niches, it
> > would be strong enough to take a few pieces of concrete inside the wall.
> > But correct me if I am wrong.
> >
> >
> >
> > On Fri, Sep 18, 2015 at 8:29 PM, Howard Switzer <howard at earthandstraw.com <mailto:howard at earthandstraw.com>>
> > wrote:
> >
> >> I know John will take good care of you, (do post your plan if you can) but
> >> basically you got a 16 foot wall braced on one end, right, so sounds like
> >> you need to brace the other end somehow. Now I expect there will be an east
> >> wall so you might consider bracing it in such a way as it could serve to
> >> buttress the end of the wall and you might want to embed some anchors in
> >> the cob for attaching that bracing wall....or you could just do a cob
> >> buttress off the end of the wall in the other direction, which is probably
> >> the better option, just guessing. You might also want to consider battering
> >> the wall a bit, wider (20") at the bottom than the top (16"), right? Might
> >> add some more stability. What are the concrete pieces doing in the middle
> >> of it?  Just trying to get rid of it or something?
> >>
> >>
> >>
> >> On Fri, Sep 18, 2015 at 2:31 PM, Malcolm Schluenderfritz <
> >> mschluenderfritz at gmail.com <mailto:mschluenderfritz at gmail.com>> wrote:
> >>
> >>> I am building a small greenhouse, 16 feet by 8 feet, and 8 feet tall. The
> >>> North and West walls will be cob, and about 18 inches thick. I will be
> >>> inserting some pieces of concrete as we go, in the center of the wall. The
> >>> walls are straight, not curved.
> >>> Do I need to add buttresses to this wall to keep it up, or is it thick
> >>> enough? The North and West walls already form a corner, so they provide at
> >>> least a little Lateral support to each other.
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> >>
> >>
> >>
> >> --
> >> Howard Switzer - Architect
> >> 668 Hurricane Creek Road
> >> Linden, TN 37096
> >> 931 589 6513 <tel:931%20589%206513>
> >> www.earthandstraw.com <http://www.earthandstraw.com/>
> >>
> >> “You never change things by fighting the existing reality.
> >> To change something, build a new model that makes the existing model
> >> obsolete.”
> >> ― Richard Buckminster Fuller
> >> <http://www.goodreads.com/author/show/165737.Richard_Buckminster_Fuller <http://www.goodreads.com/author/show/165737.Richard_Buckminster_Fuller>>
> >>
> >
> >
> >
> >
> >
> >
> >
> > --
> > Malcolm Schluenderfritz
> > Secretary,
> >
> > The Saint Isidore Society,
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> 
> 
> 
> -- 
> Malcolm Schluenderfritz
> Secretary,
> 
> The Saint Isidore Society,
> saintisidoresociety.wordpress.com <http://saintisidoresociety.wordpress.com/>