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GBlist: Re: Housing Costs (greenbuilding-digest V1 #362?)



>On 8/16/97 7:00 AM Barry Goldberg wrote:
>
>Our cohousing group is reaching the point where we have to consider our
>decisions on what construction technologies to use.  I'm trying to put
>together a chart comparing costs and other considerations for the
>options we are looking at.  I know trying to compare square foot costs
>for diferenet technologies is very crude and inaccurate and will vary
>because of where we live--southwest Colorado.  It can help give us a
>picture of what's realistic and affordable though.
>
SNIP
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The latest Solar Energy Society of Canada Conference had an illuminating
presentation by Elizabeth White, comparing stabilized, insulated rammed
earth construction versus 2x6 platform frame wall construction in a BC
Coastal context.

The study compared initial capital cost, space heating energy, maintenance,
environmental impacts, and local economic benefits of the two wall
constructions for a 1500 sq.ft. single storey slab-on-grade house, 
with 160' linear feet of wall.  The location was Saltspring Island, at the
south end of the Georgia Strait, which separates Vancouver Island from the
mainland.

The SRE wall construction examined is somewhat different from the classical
stabilized rammed construction more common south of the border.  From
outside to inside, this SRE wall is constructed of 8" rammed earth with
bamboo reinforcing, 4" isocyanurate rigid insulation, and 10" rammed earth
with bamboo reinforcing.  The wall is placed on a 36" steel reinforced
concrete footing, and has a concrete bond beam at the top.  Thermal
resistance is R25, and compressive strength  tested between 1378 and 2393
psi. Finish was clear acrylic or white glue for anti-dusting.  The rammed
earth had 15% cement content.

The frame wall for comparison was (outside to inside) cedar siding on Tyvek
sheathing paper over 1" R5 foamboard over 2x6 frame (centres not mentioned)
with R20 f/g batt insulation,