subject: Learn To Install Replacement Windows In Your Home The Right Way [print this page] . Too often, a poor installation job leads to a window which leaks water and allows air to infiltrate a home, which can negate all of the energy-efficient benefits of new replacement windows.
Weather-Tight Windows Need Proper Window Flashing
Here's how to do it: Beginning with an existing wall opening and a properly sized window, make sure that the home's vapor barrier (a.k.a. house-wrap) wraps around the edges of the window opening. Apply a continuous bead of exterior grade caulking to the backside of the window's nailing fin, which extends around the entire perimeter of the replacement window. From the outside of the house, insert the window into the wall opening. Center the window, making sure that the window is sitting level in the framed opening. Using some 2-inch roofing nails, attach the window to the exterior wall by setting the nails into the pre-drilled nailing holes which are spaced around the window's nailing fin. Do not set any nails through the top horizontal nailing fin, unless specifically instructed to do so by the installation instructions which came with the new window. Apply strips of 6-inch flashing tape to both sides of the window, making sure to completely cover the nailing fin and the seam between the window and the exterior wall of the house. Next, apply a strip of flashing tape to the top of the window, making sure to completely cover the nailing fin and the top edges of the vertical pieces of flashing tape. Install the exterior window trim pieces. Attach a piece of "L" shaped metal flashing to the house, which fits under the siding and over the top of the upper piece of window trim. This will act as a drip cap and should shed any water which gets behind the siding. Apply a continuous bead of exterior grade caulking to all the seams between the window frame and the trim pieces. Then caulk all of the seams between the trim pieces and the siding.
When you install replacement windows, make sure that you have created a shingle effect with all of the window flashing and windows parts. This shingle effect ensures that any water which gets behind the trim and siding will shed properly and not enter into your house.
