LARSON TRUSS SYSTEMS

[dominick...@energy.com]

I am trying to get information on a "Larson Truss" - a type of wall truss
attached to the exterior of sheathing to act as a "double-wall" insulation bay.
The concept seems simple but I've not seen any homes with this technique older
than 3 years. Are there tested methods for construction? Apparently, it is a
design by a John Larson from Edmonton. Any help would be appreciated. Thanks.
-Dom Tammaro

[Peter Hill]

Fine Homebuilding magazine, "Annual Issue on Houses," Spring '94,
no. 87. Taunton Press, Newtown CT, 1-800-888-8286.

The 4-page article also refers back to FHB #20.

Larson trusses were developed "more than a decade ago by John
Larson, a builder in Alberta, Canada. The system is simply a
series of lightweight racks that hold large amounts of
insulation. They can be used in new construction or for
retrofits." The trusses are outside the structural stud walls
and roof framing.

The article describes a house built in Vermont in 1991. It has
12" of continuous insulation in Larson trusses. 2600 gross square
feet (apparently all finished; no garage). $48 per square
foot. The price includes some useful features like low-e glass
and a Van-EE heat exchanger.

I don't like the construction cost comparison they provide; they
detail extra costs of the Larson truss system, partially offset
by savings in comparison with a conventionally-framed house.
They didn't use a conventional heating system, which saved them
$7200. (They heat this house with a wood stove.) I'd add the
conventional heating system, which would make it about 10% more
expensive than conventional construction.

--Peter

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