[Greenbuilding] FW: Thermal envelope

[JOHN SALMEN]

I would agree that its not working. The concept of structure to the interior
is good but practically the exterior needs the rigidity as its subject to
the most movement. The amount of 'blocking'and detailing required to provide
exterior support is a waste of labour, material and potential insulation
area. Foundations have been oversized to provide for wall thickness, etc.
Outside of the solid blocking I've had to detail 1/2 x 3" width material for
the rainscreen - it's the only width that works decently to avoid
compressing the foam.

Working to the interior is a better solution but only if you have elect. And
plumbing contractors willing to work to that - my assembly for that has been
been:

Exterior siding
3/8 to 1/2" rainscreen
Sheathing
2x4 frame w/ blanket infill
3"  eps fastened with either metal tbar horiz btwn 24" eps boards or metal
banding over the foam or routed for 1/2 x 3" ply straps or horiz. 1/2x3
straps over the foam. Note technically for v.b. equivalence you might have
to go to 3.5 or 4" or type 2 eps or deal with it at the drywall level or use
poly.

The goal is to minimize wood usage both in framing and trim. Insul to the
interior allows for the potential of using drywall returns or some paint
grade material for the infill up to the window or door frame material.



JOHN SALMEN ENVIRONMENTAL DESIGN
4465 UPHILL RD,. DUNCAN, B.C.  CANADA, V9L 6M7
PH 250 748 7672 FAX 250 748 7612 CELL 250 246 8541
terrain at shaw.ca

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Alan Abrams
Sent: April 23, 2008 7:24 AM
To: 'GB REPP'
Subject: [Greenbuilding] FW: Thermal envelope


blast it, siding, corner boards, windows, doors, and their associated
flashings were meant to be nailed to good solid sheathing.  next project,
I'm going to do what I've been threatening to do for some time--frame up
with 2x4 studs with ordinary sheathing, shoot it with cellulose or foam, and
nail 1-1/2"x2" horizontal runners to the inside of the studs with 2" xps
between the runners.  everything's nice and modular.  fastening cladding to
foam is like trying to put panty hose on a porcupine.  it just ruins the
stockings and ?!$$#$ off the porcupine.  turn this bloody thermal bridging
thing inside out.

-AA


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