Instructions / Assembly

Here is a basic, step-by-step guide to installing a nail ﬁn type, new construction

window, including recommended ﬂashing details often used in the industry.

NEW CONSTRUCTION

WINDOW INSTALLATION INSTRUCTIONS

Sealing The Window (REQUIRED)

1. Apply a generous (at least 3/8”), continuous bead of exterior-grade sealant

designed for window installation, on the back side of the nail ﬁn, across the top

portion and vertical sides of the window within close proximity of, or directly over,

the nail holes in the nail ﬁn. NOTE: For aluminum or aluminum-clad windows,

sealant must be applied directly over any joints located at the corners. The bottom

nail ﬁn must have a continuous bead of sealant applied. (See Figure A).

2. Leave two 2” skip gaps per unit in the sealant creating a discontinuous bead of

sealant to allow any moisture trapped in the sill pan ﬂashing area to escape to the

exterior of the home. (See Figure B).

STEP 4:

Figure A

Figure B

Setting The Window (REQUIRED)

1. Place the window in the RO, centering it from side to side in the opening

as needed.

2. Close and lock all locks to help square the window up.

3. If the sill of the rough opening is not level and true, place shims as needed to

prevent the sill from bowing or sagging, otherwise you may place the window unit

directly onto the rough opening sill. (If your window is a horizontal sliding window,

make sure each meeting rail is supported.)

STEP 5:

Shims

3. Press the ﬂashing ﬁrmly to the horizontal sill plate. Fit the ﬂashing tightly to

the corners and extend the ﬂashing a minimum of 6” up each side of the RO

side jambs.

4. At this point, if the membrane is a ﬂexible material designed to stretch, fan the

material at the bottom corners of the sill while pressing it at the same time

ensuring that the ﬂashing covers at least 2” past the outside edge of the sill as

seen here. Otherwise, follow the membrane ﬂashing manufacturer’s speciﬁc

instructions for application details.

NOTE: A vertically mulled combination window

unit will require more gaps depending on

the number of units combined to create the

combination, for example, a twin needs four

gaps, a triple needs six gaps, etc.).