SB: Re: Re: earth plaster for commercial use

["John Swearingen" <john@skillful-means.com>]

----- Original Message -----
From: "Rob Tom" <ArchiLogic@yahoo.ca>
To: "John Swearingen" <john@skillful-means.com>; "Athena & Bill Steen"
<absteen@dakotacom.net>
Cc: <strawbale@crest.org>
Sent: Monday, September 23, 2002 2:29 PM
Subject: SB: Re: earth plaster for commercial use


>
> Dear John;
>
> Rather than echo the thoughts that BCJohn and Beel have already
> offered and with which I must agree,  I 'd like to raise the point
> that the "conventional" wall surfacing materials which are typically
> used in medical offices and clinics (namely gypsum board sheathing)
> don't stand up all that well to "banging, scratching, kids and
> "mops" either.
>

Quite right.  The current office has bare sheetrock, and, actually, it
doesn't seem to have suffered too much abuse (this is not the ER of San
Franscisco General)


[sneeeeep]

>
 >
>
> That being said, I do wonder what logic behind using PISE
> would be (in any scenario, not  just the Skillful Meany's proposed
> clinical setting) ?
>
> Granted, PISE requires only about 15% of the cement that a Portland
> cement plaster mix requires on a per unit volume basis but the PISE
> typically has to be applied a lot thicker than would a PC plaster so
> there may not be any real reduction in the amount of  cement used, if
> one is vying for Greenie points.

We do have a thermal stragety of increasing the mass of the building.  Since
this is a place where people lie on tables in skimpy little robe things, we
feel that the range of temperatures inside the building should be smaller
than would be tolerable (or perhaps desirable) in a residence.  So, more
plaster is a Good Thing.  If the evil cement allows us to lighten the
structure and provides mass--and also hardens the surface thereby
eliminating the need for other materials--then perhaps it's paid for itself.

>
> Moreover, "dirt" is classified as a contaminant in Portland cement
> mixes and its inclusion is viewed as being detrimental to the
> performance of the finished product (from a concrete or PC stucco
> point of view).
>
> To get the best results from Portland cement.....

[sneep}

We have a pise mix that gets up to 2500 or 3000 psf.
>
>
> The "proper" aggregate to use with Portland cement (from a
> performance perspective) is clean sand, and it's just as natural as
> clayey earth, so why is a PC plaster viewed as being less natural than
> PISE ? If anything, one might argue that PISE is less natural, the
> process requiring fancy gizmos in order to produce it whereas with
> PC plaster, a little sweat and a wheelbarrow for mixing it in is all that
> is required.

I agree.  However, the fancy gizmos (gunnite machine) allow the use of less
cement (less water = higher strength = less cement) than required with a wet
and sloppy stucco.

[sneep]
> And if finishing the earthen plaster with a coat of lime plaster anyway,
> why would the substrate need any Portland cement in it  at all ?
>

For hardness...a veneer is only as strong as its' substrate.

> I gather that the clients want to make a statement of their philosophy
> by using natural materials like SB & earth ?

Our client, as a doctor, sees many many people suffering from environmental
illnesses.  Although I tried to argue that outgassing carpets, vinyl
flooring, etc. would be a good business investment, he stubbornly insists on
setting a good example...

[sneep]

>>>>>perhaps the design
> should try to accommodate the qualities (and weaknesses) of the
> unadulterated earthen material  (easy for me to spout, but not so easy
> to implement  but do-able  nonetheless... I suspect) by configuring it
> and the building elements in such a way that mops/jamfaces/violent
> adults cannot wreak havoc upon the material.

We can do a lot with design, for instance a concrete toe-up as a mop board.
Most hospitals have veneer plaster to harden the drywall, etc.  It seems the
same approach could be used here--apply a hard, smooth-coat plaster (if only
as a wainscott) over the earth or pise, and assume that it might need to be
renewed every few years.  Such work would be relatively easy in a medical
office, which is rather sparsely furnished, than most homes, where the walls
are covered with furniture, beds, couches, cd racks...which all must be
moved in order to "paint".

So....Beeel, UpsideDown John...anyone else.  What would be a smooth, hard
surface to go over pise or earth plaster.....

John (on the Hard Shell) Swearingen






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