Part 2: Installing a Nail Fin Window Exterior Rigid-Foam Insulation

Use a manufacturer-approved type of sealant to bond the window to the preliminary flashing before setting, squaring, and fastening the window to the framing.
To learn how to install nail-fin windows in 5 common wall types, check out this playlist: www.finehomebu...
When installing a nail-fin window in a wall with exterior rigid-foam insulation, the process starts with shims under the window-in this case, cutoffs of bevel cedar siding. Besides creating a level surface, these shims support the jambs to prevent deflection, and also create a gap under the window, which aids in the drainage process, should that ever become necessary. Care is also taken to center the window in the opening, setting the stage for effective air-sealing work, which will come later in the process.
Depending on the style of nail fin found on your particular window, the process of preparing the unit for installation may vary. On this Pella window, the metal fins are attached at the factory and folded down for shipping. After getting the nailing fins unfolded, the window is test-fit and traced, providing a target area for applying sealant under the fins. If all of the above is done carefully, setting and fastening the window is fast and easy.
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[@friendphil]

I’m curious why to check for square? The whole window assembly is built around the glass panel(s), so if it’s not square (which is very, very unlikely) one would need to replace it or just ‘go with it”, correct?

[@biglos1999]

You make sure its square because the window assembly has give built into it. If it was off you would shim the appropriate side from the inside, remeasure then attach the window as normal.

[@bobe5710]

I think I would've test fitted the window with the bevel and shims before spreading all the goo.

[@MrBrianDuga]

What screws are those? They look great for this.

[@benjaminstrickland995]

Looks like GRK truss head cabinet screws

[@texascraftsman7215]

Why did you come up 1/2 inch looks like the bottom screws missed the framing they all angle up like they missed could you get by with Less to insure you have plenty to screw to?

[@bighammer3464]

@@texascraftsman7215 the entire window is framed in wood. There’s no way to miss