[Greenbuilding] adobe/stucco/lime plaster

[Chris Green]

Nitya Akeroyd wrote:
> Hi folks
>
> am catching up on reading email, so here is another comment:
> <snip>
> A while back when I was researching mud and lime plasters, I read somewhere that using cement stucco over adobe or mud brick is not good. The cement wicks water, and the mud wall behind it gets wet and begins to disintegrate.
Another problem which showed up over the years is that cement stucco and 
mortar expands and contracts at a different rate than the adobe, so the 
bond between the two fails. Any liquid which then gets between the two 
quickly erodes the earthen mix.
>  When I read the example above it reminded me of that and seems to bear that out. Apparently it is preferable to use lime plaster over adobe or straw bale etc when you want a more durable finish as it will breathe and will not wick or trap moisture in the same way. In one example I read about, an historic adobe church had been restored using cement stucco as they didn't want the maintenance of having to redo the lime plaster periodically.
The US National Parks Service has guidelines for the maintenance of 
adobe structures as part of their Heritage Preservation  tasks. 
http://www.nps.gov/history/hps/tps/briefs/brief05.htm
There's a photo of the  mission church here as well.
I recall reading somewhere that the community around the church has gone 
back to having organized work bees to repair the earthen plaster.

BTW, if you haven't seen it yet, you might be interested in looking at 
the Poeh Center Museum in New Mexico. 
http://www.eartharchitecture.org/index.php?/categories/60-United-States-New-Mexico
http://www.poehmuseum.com/facilities/fac_over.html

The tower is the tallest adobe structure in New Mexico, and is iconic.

Cheers,

Chris Green.