How to Replace Full Frame Window
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How to Replace Full Frame Window

October 21, 2019


Refer to the most current installation
instructions on installPella.com for the tools, materials and specific steps
needed to install your Pella product. Always use appropriate personal
protective equipment. Score the paint or varnish between the
trim and wall then carefully remove the interior trim. Score the paint or varnish between the
trim and wall then carefully remove the exterior trim, casing or brick mold. Leave any existing head flashing in
place. Carefully remove the old window. Inspect the existing wall. Clean the
opening, including the surrounding wall, to ensure it is dry and free of any dirt,
oil or debris. Check the opening for plumb and level. Confirm that the window opening is 1/2
to 3/4 of an inch larger than the window in width and height. If there is existing building wrap, fold
up the top flap and temporarily secure it with flashing tape. Cut two pieces of
flashing tape that are 12 inches longer than the opening width. Apply the first
piece of flashing tape so six inches of the tape extends up each side of the
opening. The tape should overlap the building wrap onto the wall surface one
inch. Cut small tabs in each corner and fold the tape down, pressing it onto the
building wrap. Make sure there are no voids in the corners. Apply the second
piece of flashing tape so six inches of the tape extends up each side of the
opening. The tape should overlap the first piece of flashing tape one inch.
Cut two pieces of flashing tape equal to the height of the opening. Apply one
piece to each side of the opening. Making sure each piece extends onto the framing
one-inch. Press the tape down firmly. Place and level shims on the sill a half
inch from each side as well as under any mullions. Refer to the installation
instruction for additional shimming requirements. Attach the shims with
roofing nails or flashing tape. Apply a continuous 3/8 inch tall bead of
sealant at the top and sides of the opening. Place the sealant 1/2 inch from
the edge of the opening. Center the window in the opening on the
sill shims. Make sure the nailing fin makes contact with the wall on all sides.
Drive two fasteners – one near each end of the top nailing fin. Refer to the
installation instructions for fastener requirements. Place shims according to
the installation instructions to make the window plumb and square and to keep
the sash to frame gap, or reveal, consistent. Check the window placement
within the wall by measuring from the interior surface of the window or jamb
extension to the interior surface of the wall. The measurement should be
consistent. Drive two more fasteners – one near each end of the sill nailing fin. Check for smooth operation. Refer to the
installation instructions to make any necessary adjustments. Drive the
remaining fasteners into the nailing fin. Refer to the instructions for fastener
type and spacing. Cut two pieces of flashing tape four
inches taller than the window. Apply each piece one-half inch onto the window
frame over the nailing fin and onto the sheathing or building wrap so it extends
two inches above and below the window. Press the tape down firmly. Cut one piece
of flashing tape long enough to extend one inch past both side flashing tapes.
Apply it at the top one-half inch onto the window frame over the nailing fin
and onto the sheathing so it extends one inch past each side flashing tape. Press
the tape down firmly. Fold down the top flap of building wrap. Cut and apply two
pieces of flashing tape over each diagonal cut. Extend the tape one inch
past the end of the cut onto the building wrap. Use a low pressure polyurethane window
and door insulating foam sealant to create an interior seal. Read the
directions on the can before use. Insert the nozzle or straw 1-inch into the
space between the window and wall. Place a 1 inch deep bead of foam to allow for
expansion. When applying trim or other finished
materials, leave adequate space between the window frame and the new trim for
sealant. After the application of trim, insert backer rod in the space between
the window and the siding or trim. Apply a continuous bead of Pella window and door
installation sealant over the backer rod. Shape, tool and clean any excess sealant.
Apply sealant between the siding and trim at the sides and bottom. At the top, apply sealant under the head
flashing across the front and sides.

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  1. I'm replacing a Pella window that was not installed properly and my problem is. It has two crank out Windows with one stationary window in the center. Well, I have the replacement window but this window had a transom window which is not getting replaced and it's mulled together. I need to be able to remove mull without damaging it or be able to get another one to mull the window back together

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