'Bumped out' window wrapping

[ThingOfBeauty]

We're doing a job where the windows will be mounted 3" outside of the wall sheathing. It's an architect-specified detail to make the windows look more authentic in the stone-veneered walls.

There are 2x boxes surrounding each window, they were ripped to width so they project 3" out past the plywood. The windows will mount to the outside edge of these boxes.

I like to think we have a decent idea on how to wrap them but would love to find a written standard or set of instructions somewhere to check our thoughts.

We're planning to wrap 12" wide SAF out on the housewrap a few inches, and all the way to the inside of the 2x box, on all four sides.
We'll probably use FlexWrap to make a sill pan. We also had the bottom piece of the box installed on a 15 degree slope to the outside and will fold up the inside of the sill pan material.

As usual we will also integrate a masonry through-flashing at the bottom before we wrap the rest, so any water that hits the wrap is directed out just below the unit.

Head flashing will either be SAF or metal. SInce there's a flashed steel masonry lintel immediately above the window box we may just go with the tape on the box & window and use metal on the lintel edge.

Anyway, would love suggestions or especially a resource we can bring out for discussion.
Thanks,

[NW Architect]

I'd add a slope to the top of the box - I usually spec a piece of tapered cedar siding. SAF over that should do. Use somebody's preformed corners for the corners of the box-to-wall intersection and "gift wrap" all the outside corners. Vaproshield now has their stuff available with a self-adhesive backing. I'd use that to wrap the box so that the wrab is vapor permeable. Then install a SAF sill pan. Then install the windows. Then seal the flanges to the Vaproshield with a 4" SAF at jambs and 12" SAF or sheet metal at head.

Finally, make sure the stone guys put sealant joints between stone and window. leaving weep slots at the head.

[davenorthup]

Doug - we have done exactly that for REMOTE walls. CCHRC has a detail for it; but you are on the track...

[Bill Robinson]

Wrap it and slope it Doug, yeah, that is it.

Think no horizontal surfaces on the drainage plane.

Detail it so everything is shingle style.

Sounds so basic yet there are many times when in a more complicated detail the sequencing from bottom to top gets turned around.

Fortifiber has some nice pre-formed corners

If there is a good 24" or so overhang this will work fine.

If it is 6" or less you may need to double up.
.

[NW Architect]

Heard this in a seminar and it boils it down nicely, without making any distinction/confusion between materials: "That which is above must lap over that which is below."

[Bill Robinson]

Or....
"what is below must be covered by what is above" :)

[NW Architect]

If I specified the former, but got the latter, I'd pass it!

[Bill Robinson]

Now that is a relief.

For a moment I thought it would need to be reversed.

And that is where the problem began.

[Ted S.]

It's an architect-specified detail.............

No, here's where the problem began...

[Bill Robinson]

I was trying to go easy on our resident architect...
However, if the window fits.......

[Ted S.]

I'm allowed to pick on architects, I am one. NW I am sure is ok with it, bad or no architect's details is his job security!

[ThingOfBeauty]

NW, I've seen that Vaproshield seems to have a lot of the Washington-Oregon market. Perhaps its our mild weather (4500HDD) but we seem to use a lot of vapor-impermeable SAF and regular old housewrap (Tyvek for us) around here. Does permeable tape and Vaproshield housewrap work better for you?
We actually looked into using Vaproshield's self-adhering housewrap on this project but decided the $3500 in material cost would be better spent elsewhere.

[NW Architect]

ToB:
Vaproshield is seldom used on single family homes but IS used quite a bit on multi-family and commercial projects. IMHO the two main reasons for using it are not building science related, but construction related. We build in the rain and in the wind. When installed over rain wetted building materials, the high vapor permeability allows for rapid drying of those materials. And, when properly fastened (cap nails to framing) the stuff doesn't blow off.

As for your bump-out, my reason for suggesting it there was the relatively large area that would otherwise be covered by vapor impermeable SAF. Assuming vapor retarders are required on the warm side of insulation, the box is going to wind up having vapor retarder inside and vapor barrier outside. May or may not create a problem. Vaproshield avoids the possibility