Installing Windows in a Deep Wall

Placetailor's deep wall system is simple: a 16-inch-thick double stud wall framed with 2x4 studs, connected with gussets at mid-stud height.

Because the air control layer of the building is at the exterior skin, including the windows, all of the seams in the window buck and window opening are taped using Siga Wigluv tape. The outboard window faces are taped to the OSB—tape is applied first to the sill.

The Zip System sheathing and joint tape form the weather-resistive barrier. To hold the vertical ship-lap board siding off the wall and create a space for drainage and air-drying, Placetailor uses strapping made from corrugated plastic signboard, bought for a few dollars a sheet at an office supply store and ripped into strips.

... then to side jamb joints

... and the head jamb

Strips of tape are also applied in the window buck at joints and in corners.

Finally, a small patch of tape is applied over the complicated corner intersections of the sill with the jambs and the wall sheathing (7). Everything inboard of the window plane, including the inner part of the window bucks, is left untaped so that the wall can dry to the inside.

Before the windows are set (Placetailor is using European-made, triple-glazed Schuco tilt-and-turns), temporary 2x3 rails are fastened across the window opening to serve as positive stops that hold the window flush with the wall sheathing.

Inside the house, each window is lifted into the opening and positioned tightly against the 2x3 rails ...

... where it is secured with two temporary blocks screwed top and bottom to the window buck side jambs.

The temporary 2x3 rails and blocks hold the window in plane while the crew fine-tunes the window's placement. First, the window is roughly centered at the head jamb with shims, then it's precisely centered at the sill by measuring off the window buck.

The crew fine-tunes the hinge jamb using pry-bars and shims ...

... and makes a final check for plumb.

They repeat the process at the sill, first checking for level ...

... then fine-tuning with shims.

Schuco windows are held in place by self-tapping lag screws supplied with the units and driven through holes predrilled in the frame.

This window gets eight screws: three through each side jamb, and two through the top rail.

Setting the windows flush to the exterior sheathing makes it simple to integrate them into the weather-resistive barrier and drainage plane by taping the exterior face of the window frame to the Zip sheathing with Siga Wigluv tape.

Place­tailor trims the window out with a simple custom trim package.

Where the vertical ship-lap board siding butts against the trim, the joints are left uncaulked to promote drying.

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