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GSBN:Foundations and Living Roofs



<x-charset iso-8859-1>Chris et al,

Regarding your request for reduced concrete use ideas and living roof concerns.

Fly ash, a recycled waste from coal fired furnaces, has been used for several years to reduce cement content in concrete. Most of our concrete
batching plants have prepared formulas for different concrete applications. Depending on structural requirements the fly ash replacement of cement
may vary between 20% and 30%. Since fly ash retards concrete cure time its use in colder conditions may not be advisable.

Stem wall foundations are designed for my houses up here in the Pacific Northwest where the land is usually sloped and earthen floors aren?t an
option. The stem walls support engineered lumber joists and sub floor construction. This is the level on which I begin my load bearing walls.
Plastic strapping is placed under the joists and up over the top plate to tie straw bale walls to the foundation.

To support double bale wide walls for the Saudi Arabian library project I used two 20 cm, reinforced, concrete block stem walls 90 cm on center.
Between the two walls we back filled and compacted the excavated soil. For this project I used two string bales side by side for the double bale
wide walls to give me the 4 meter high bearing walls used on the library?s perimeter.

I first heard of living roofs that used lightweight growth mediums and drought resistant plants, in the early 1990?s. They were developed in
Belgium for use on roofs and to cover concrete paved roadway divider strips. Most of the ones I hear of today are used on large urban buildings as
rainwater retention systems. What is attractive to me about them for natural building is a living roof that weighs about 10 pounds per square foot
thoroughly saturated. Another attraction is as an UV barrier. One can hide an inexpensive asphalt roll roofing, which should last indefinitely,
under this living roof. For links to living roof systems check out http://www.ecobuilding.org/proj/ecoroof

Hope this is the kind of feed back you were looking for.

Chris
Christopher Stafford Architects, Inc.
1044 Water Street, #326
Pt. Townsend, WA 98368
360/379-8541