[Greenbuilding] windows - flush vs recessed

[Alan Abrams]

> One design to avoid at all costs is the one which covers the window frame
> with exterior insulation, therbey trapping rain leaks in the wall (but
> reducing building heat loss by as much as 1%).
>
> John
>


what this suggests then is that the drainage plane is outside the exterior
insulation, right?  I'm trying to recall the arrangement in the NIST net
zero test house, which has a conventional frame wall with a membrane
applied to the structural sheathing, and then two layers of foil faced
foam, then furring and siding.  but (having loaned the drawings to someone
who did not return them) I can't recall where the windows occurred in the
section, and if the membrane was the primary drainage plane.

wrt to protecting inner layers of wall when windows are set in from the
exterior plane--note that conventional US clad windows, such as
Weathershield, have a groove to receive metal flashing in the outermost
edge of the projecting part of the extrusion.

conversely, in a passive house under construction in Arlington VA, which I
visited yesterday, the windows had no flanges, but were attached with tabs
that projected toward the inside edge of the wall.  integration with the
rainscreen was not complete yet, but seemed to rely heavily on butyl
tape--whereas the PH detail manual--and other photos I've seen--feature
metal extensions at least at to cover the sill.  (btw, the Arlington
windows were untreated vinyl by Intus, rated at +/- U-0.14)

-a
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