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What You Need to Know When Replacing a Window in an Existing Wall

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When it comes to home repair tasks, few choices can make a more dramatic change than replacing your home windows. But while many other improvements can be completed with a little effort and a good plan, replacing a home window needs serious work and a piece of technical smarts.

Because of that, replacing your windows is no easy task. You’ll want to identify what type of window is necessary, the specific plans required for replacing the window based on the size of the opening, and what materials it will take to create the correct fit for your new window. Here are a few thoughts you may wish to review:

What is Your Frame’s Condition?

The condition, or even presence, of the window frame is the first major factor in matching the proper type of window to your replacement job. If you are constructing a new window frame, taking out a damaged frame, or otherwise exposing the wall down to the studs, choose new construction windows, also known as full frame replacement windows. Pocket replacement windows can be installed in projects where the window frame is not being removed, is in good condition and properly leveled.

The size of your window will also play a role in which type of window you should install. Replacing a window with a window that is a similar size will make a pocket replacement window a better choice. However, upgrading your window to a larger size will require uninstalling the previous frame and creating a new frame to fit your larger window as part of a full frame installation. Because of that, a full frame replacement window will be needed for the job.

Removing the Old Frame

Selecting a full frame replacement window, as the name suggests, typically means replacing the existing window frame, sashes and screen. This can typically be taken care of with a utility knife, screwdrivers, pry bar, hammer, putty knife and circular saw, depending on your installed window.

To protect your home exterior trim when removing the frame, lay a block of wood between the wall material and window, and then use a pry bar to clear away the existing window trim.

Full Frame Window Options

Two window styles can meet your needs when undergoing a full frame window installation: Nail fin windows and block frame windows.

Nail fin windows are common in new construction projects, or any remodel where the walls will be exposed to the frame (studs). These windows include a thin piece of metal connected to the window itself that runs around the edges of the window frame. When adding the window to a new frame, this nail fin joins the window directly to the house’s studs and is placed between the interior and exterior of your home.

Adding a nail fin window can be both labor-intensive and may require the building of a new window frame or removal of siding so the installer can apply the nail fin to the studs. Nail fin windows are better to install in new construction (for example, when adding a room to your house), as the window is placed before the rest of the wall is completed around it. Further, if you are looking to place a nail fin window to an existing wall in a section of the house where a stone or brick exterior would also have to be replaced, the job might not be worth the effort needed.

Block frame windows offer an option for projects where nail fin windows would be more cumbersome to place. These windows come without a nail fin and are designed to fit inside existing window flashing (the area of the window that includes material to prevent water from entering into the walls) with minor new construction work. This makes block frame windows a standard replacement for a number of older homes that currently have a window structure built or homes with siding or brick exteriors that would otherwise have to be harmed or removed to install a nail fin window.

Using Your Existing Frame

Replacement pocket windows are somewhat different than full frame replacement windows and are designed to be added inside an existing window frame. While the existing window sashes and exterior stops of the window should be uninstalled for the new window to be placed, pocket replacements allow homeowners to keep the original frame, trim, siding and casing.

Just as with full frame window replacement, the wall exterior around the window opening will impact how the pocket replacement process works, this time with less steps. As opposed to full frame replacement window removal, much of the existing sash, hinges and operating hardware will be connected with screws that must be taken out before pulling out the head, jamb and sill stops with a pry-bar. Like the full frame replacement window, using a piece of wood to shield your wall exterior when uninstalling the old window is a smart way to help defend against any accidental damage.

After taking out the existing sashes and inspecting and readying the opening, the replacement window can be set into the opening and existing frame. Make sure to plumb, level and square the window at each step of the installation to ensure a proper, balanced fit.

Consult with a Professional Installer

The steps required to replace a window in an existing wall demand a clear vision of your design goals and a exact installation of your window. You can review detailed step-by-step installation manuals based on both the type of window, as well as the type of window opening, at

Even with these detailed instructions, many homeowners find that the idea of unintended damage to their home (as well as the time, price and labor demanded) make window installation a project they’d rather not take on. Planning with a professional home window installation expert, like the staff at Pella of Boone, provides the technical knowledge and know-how to do the job safely.

Wherever you are in your home window replacement plans, contact a Pella professional today. Even if you are considering replacing a home window on your own, a professional can help you choose what installation method is right for your home and discuss installation options.

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