Re: SB: skins of earth and cement

[SZori@aol.com]

The two factors that I would consider to see if earth plaster on interior and cement / lime stucco will work are:

1.   Design strength of stucco/stucco skins vs stucco/earth plaster. And how does this compare to the required structural strength of the total Sb assembly for your particular building.

2.   Vapor transmission rates. If vapor transmission rate of earth plaster is greater than vapor transmission rate of stucco exterior, then the earth plaster could only be used on interior if it is finished with a clear vapor barrier material. Otherwise, you run the risk of moisture collecting in the SB and causing mold/mildue and SB deterioration.  If vapor transmission rate of earth plaster is equal to or less than that of stucco exterior, then OK, as long as skin structural strength is approved.

Sergio Zori Architect
Energy Efficient / Healthy Buildings
szori@aol.com