COLUMN BUILDING SCIENCES To get the windows to be "outies" with mineral fiber insulation (stone wool), we need to do a couple of things. We need to line the window opening with wood framing that is the thickness of the mineral fiber insulation (stone wool) and this "structural extension" needs to be wide enough on its face to be able to integrate the window flange with the water control layer at the face of the structural sheathing. This is typically 2 × material. With 1.5 in. (38 mm) thick mineral fiber insulation (stone wool), the rough opening is "picture framed" with 2×2s. If you want to go thicker with the continuous mineral fiber insulation (stone wool), use 2×4s or 2×6's-trimmed to the correct thickness-for the "picture framing." Check out the sequence of installation (Figure 8). Note that liquid applied flashing is used to provide continuity with the water control layer on the face of the structural sheathing and the "picture framing" "structural extension." The liquid applied flashing wraps into the frame opening and creates the PHOTO 2 Structural Box. Typically plywood or OSB protruding past the exterior face of the framing, extending the thickness of the continuous insulation. How thick can you go with the continuous insulation with the structural box? Typically 4 to 6 in. FIGURE 6 Window Installation Sequence for "Outies." The water and air control layer is the face of the continuous insulation. Note that the water control of the flanged window lines up with the water control of the face of the continuous insulation. Again, note the sloping sill and that the pan flashing can be liquid applied or a formable membrane. Again, note that sealant is not necessary behind the window flanges. And finally, note there is no wood behind the window flange-you don't need any-the flange is seated directly over the continuous insulation-you attach the window through the flange and continuous insulation to the framing with long screws. A B C D E A) Insulating sheathing installed over frame wall; B) Install beveled wood siding in frame wall opening at sill to create slope; C) Install formable flashing at sill; D) Install window plumb, level and square; E) Install flashing tape at jambs. F G H I J F) Install flashing tape at head; G) Install sheathing tape over flashing tape at head to terminate flashing tape; H) Interior view prior to window installation; I) Interior view after window installation; J) Air seal window around entire perimeter on interior with sealant and sealant backer rod. APRI L 2015 ashrae.org ASHRAE JOURNAL 61