[Greenbuilding] adobe/stucco/lime plaster

[Nitya Akeroyd]

Hi folks

am catching up on reading email, so here is another comment:

> the first was the traditional, based on the practice of the Pueblo Indians,
in which the adobe walls were plastered by hand with the adobe soil and
straw mix.  Head joints in the bond were left un-mortared to provide a key.
The coating was exposed to rain (avg 10" / yr), and refreshed periodically.

The alternate was to wrap the walls with stucco netting (20 ga 1 1/2" hex,
furred out about 1/4") and plaster it with 3 coats of Portland/lime/sand
mix.  The ferro cement cladding was robust--I can recall seeing abandoned
houses with collapsing roofs, and the adobe bricks melted away--and the thin
stucco shell still supporting what remained of the roof.

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. 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. But then they noticed that the walls were deteriorating and in the end had to remove the stucco and re-do it with lime plaster.

Nitya


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