Window Installation

Window Installation Techniques For You

Window installation is one of the most important steps in a home renovation project. It’s also one of the most commonly mistreated steps, which can lead to serious problems down the road.

This blog will dive into the different window installation techniques used by professionals, from the replacement industry to custom home builders.


The first step is to clear a walking path inside and outside the window area. This includes removing furniture, area rugs, plants, toys and decorations. It’s also important to have an arrangement for what you’ll do with children and pets during the installation process. You’ll need to keep them away from the construction zone and ensure they don’t get in the way of the workers. You may want to consider arranging for someone to watch them while you’re at work or putting them in a safe place, like a neighbor’s house.

Next, the crew will use a hand-held blow torch to heat up the caulking around the old window frame and the wood sash. This makes it easier to remove the old sash and window frame without damaging them. After that, they’ll inspect the framing and casing to make sure it’s in good condition. If it isn’t, they’ll be able to make necessary repairs before installing the new windows.

Often, the installer will need to install some shims in and around the opening. These will keep the frame straight and level. It’s also a good idea to apply elastomeric caulk in and around the new window to protect it from moisture.

In some cases, the installer will also need to add a drainage membrane system to the existing exterior cladding material. This helps ensure any water that gets behind the house wrap is drained down and out over the flashing tape rather than into the wall cavity. This will help prevent water damage inside the home and prolong the life of the new windows. The contractor will also install flashing tape along the sill to prevent moisture from entering the new opening.


In a new installation, installers set the window in place against the stops, applying beads of caulk around it. They then open, close, and lock the sash to test operation, using shims where necessary. They also install a backer rod, a piece of rigid insulation to prevent thermal bridging and water channeling.

The sash is also tapped in to the frame to make sure it’s secure. The installer then applies flashing tape to the sill to form a complete water-resistant barrier. This step is especially important on older homes and in brick or stucco houses.

During the final inspection, installers should check for square. They do this by measuring diagonally in two places at the top of the window, and then making sure those measurements are the same. They should also measure the height of the sill, and adjust it if needed, to ensure that it’s plumb and level.

The installer should also check the gaps between the reveals (spaces around the frames). They should not be larger than 14 inch, as this can allow moisture to infiltrate the home. If the gaps are too large, they can be closed with shims to create better air and water barriers. Lastly, the installers should inspect and test the operability of the sash and frame, and use shims where necessary to make sure that it’s plumb, level, and square. They should also install a backer rod to prevent thermal bridging and water infiltration, and install the jambs over it. Ideally, the installer will use exterior caulk for the entire job to ensure a long life and avoid premature failure. Some contractors have a punch list crew that is responsible for all caulking and painting, which allows another set of eyes to verify that the work was done correctly.


Installing new windows or replacing old, dated ones is important for any home renovation project. Whether your goal is to update the look of your home or increase its energy efficiency, there are several important considerations for installing a window that will ensure that it is installed properly and performs at its best.

Shims can help to keep the window level and plumb during installation and help to prevent future problems like rot, water leakage or air infiltration. For this reason, it’s a good idea to use shims for all window openings. For new construction, the window frame is built a little thicker than the rough framing on both sides to allow for this. This is especially true if the building is going to be LEED, Passive House or ZNE (Zero Energy Green) rated.

When you install a full-frame replacement window, you will need to shim the head jamb and side jambs as well as the sill. It is also a good idea to shim the bottom of the window, because if the frame is not properly seated it can shift and cause problems with the operation of the sash and could even lead to rot.

If you are using shims, make sure that they are low-expanding foam intended for window and door insulation. Any other type of foam can expand too much and bow the frame of the window, causing it to not open and close properly.


Whether you’re installing full-frame windows or pocket/insert vinyl replacement windows, nailing is a key step. The window’s nail flange should be sealed before it’s set. This will help to prevent water, air, and other contaminants from entering the frame, which can cause rot and mold. A caulking gun can be used to squeeze a bead of sealant over the flange.

If you’re using latex caulk, simply wipe it down with a damp paper towel to remove any excess. After the bead of caulk dries, you can finish up the installation by installing new window stops (the strips that hold the window sashes in place). Then, install or stain the window trim to match the frame.

Before setting the window, use a level and a spirit level to make sure it’s plumb, level, and square. Shim where needed to correct any misalignment. Once the window is positioned, drive a screw through the shim and into the frame. Don’t tighten the screw too much, or it could pull the frame out of alignment.

While the installation process is fairly simple, making mistakes can have serious consequences. Getting your measurements wrong or failing to properly fasten or seal the window can affect how well the window functions and how long it lasts. With a little time and the right tools, however, replacing vinyl windows is an easy DIY project that most homeowners can complete themselves. For most, this is a job that will save them a lot of money compared to hiring professional installers. And, since the new windows will be more energy efficient than the old ones, they’ll also help to lower utility bills. So, if you’re ready to save some cash and improve your home’s energy efficiency, start learning about the best techniques for installing vinyl replacement windows!


Depending on the type of window, it may require special handling, such as removing and replacing sash weights and springs or moving a trim piece to accommodate a new window air conditioner. This is typically done outside the house to minimize disruptions to the cladding system, and it should be completed by an experienced contractor who has access to the correct tools and materials.

When the new window is in place, a contractor will check it with a level to make sure it lines up correctly with the opening and that the sashes are even. They might also add more shims to ensure the frame is square with the window opening.

The contractor will then apply construction adhesive to the bottom of the window ledge and nail it in with a pneumatic brad nailer, making sure that nails are evenly spaced along the ledge. Next, they’ll use a jigsaw to cut off the excess window ledge material.

Before installing the head casing around the new window, a contractor will take precise measurements to determine how high the head casing should be. They’ll also make a pencil mark where the point of the head casing should meet the drywall to create a 1/4-inch reveal on the wall.

To avoid a “funnel effect,” contractors must not flash the sill. Tony Reis, president of MFM Building Products, says that inexperienced installers sometimes put a window in and then cover it with flashing tape, which creates a funnel for moisture to get behind the cladding. To avoid this issue, builders should install the flashing at the bottom of the window opening and then place a water-resistant barrier over it.