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Replacement Window Installation Best Practices: A Step by Step Guide

August 11th, 2021 | 10 min. read

Replacement Window Installation Best Practices: A Step by Step Guide

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Imagine this: You’ve been in your home for quite some time now and just got your windows replaced a few years ago. Even though these are still brand new windows, you start to notice a draft when you get close to your bedroom window. 

How can air be getting through these brand new windows? 

Thinking back, you remember being frustrated with the process of shopping for new windows, leading you to give up and choose one of the least expensive contractors to get the job done. 

While the windows themselves seemed to be high-quality, going with a cheap contractor most likely led to cutting corners in the installation. 

Southwest Exteriors has been a local window replacement contractor since 1989. We specialize in installing high-quality windows from Marvin, Vistamark, and ProVia. We know how frustrating it is to have problems with your new windows because we’ve seen it many times.

The quality of installation and the craftsmanship of our work and service is one of our core values. If your windows are not installed properly, they aren’t going to last. 

With any home improvement project, the installation quality is just as important as product quality. So, how do you know what makes a high-quality window replacement?

This article will go through the steps to a window replacement and outline the practices that make a high-quality window replacement installation. We will also point out some of the low-quality methods so that you can distinguish between the two. 

After reading, you can choose a window replacement contractor that you are confident will deliver a high-quality project. 

Phase 1: Best and worst practices before your window replacement installation 

The preparation before you window installation is just as important as during the installation. You want to know that your contractor is going to take care of you throughout the entire process. 

A technical measurement or appointment before construction is crucial to finalize all details of your project and give you an opportunity to ask questions before construction. 

The importance of a technical measurement

Before any construction begins, certain steps should not be skipped to ensure a high-quality window replacement. 

An appointment should be made shortly following your initial consultation and before the first installation day to take technical measurements of all windows to be replaced. 

During your first consultation with a sales consultant, they will take measurements of your windows to give you an accurate quote. However, every window is shaped differently and shifts in a unique way. 

While taking technical measurements, the contractor should measure the window in multiple spots, typically three different spots, vertically and horizontally. This is crucial to ensure the properly sized window is ordered for your home. 

Each window must be measured at different points vertically and horizontally because, over time, the foundation of your home shifts with the earth. Foundational movement causes the windows to shift as well, and no window opening is perfectly square. 

If the window were only measured for length and width at one spot, that new window would not fit properly in the opening. This would leave larger gaps between the window and frame that would have to be filled with extra caulk. 

Filling large gaps with caulk only leaves room for seal failure in the future. This is not a best practice for a window installation. 

A technical measurement appointment is also a crucial time for your contractor to go over the details of your project with you. This should include the style and custom options you’ve chosen for your window, what to prepare before the installation, and answer any questions you may have.

After your technical measurement appointment, you should feel confident and prepared for your window replacement. 

Phase 2: Best and worst practices during your window replacement installation

Knowing the details that make a high-quality window replacement is essential to choose the right contractor. It doesn’t matter if you buy the best windows out there; if they aren’t installed correctly, they aren’t going to last as long as they should. 

Here we will outline the steps to a window replacement and point out what makes a high-quality versus low-quality installation. 

Preparing for the installation 

As soon as the crew arrives on your first installation day, a high-quality contractor will walk through the scope of your project with you, reconfirm the details, and go over the plan for the day. They should have a crew leader to handle all of this for you. 

This also provides you with another time to ask any last-minute questions. 

A great contractor will also prioritize whichever windows you may want to be replaced first. For example, if you work from home and have a home office or kids who need to nap, the contractor should replace those windows that work best with your daily schedule.

Meeting your installation crew is important for you to feel comfortable and confident in your project. Just think about how you would feel if a crew just comes up to your home, starts unloading tools, and constructing? 

Construction can be nerve-wracking, and meeting your crew and understanding the project plan is key to knowing your project will be successful. 

Preparing the construction area

Before any construction begins, the installation crew must properly prepare the areas around your home to minimize debris and possible damage. 

A high-quality contractor will place tarps around the window area and anywhere the crew will be walking. They should also take the precautions necessary to keep the site as clean as possible. Continuously sweeping, vacuuming, and cleaning during construction is a trait of a high-quality contractor. 

If it is in your contract for the crew to move furniture and wall decorations for you, they should handle them with care and move them to a safe place. 

A high-quality contractor will also be mindful of any pets or children that may accidentally come near the construction. For example, the crew should keep any baby gates or barriers closed if necessary to keep your pets and children safe. 

A crew that does not take any cleanliness or safety precautions does not care about keeping your home tidy and your family safe. This is why it is imperative to know the details of a contractor’s installation process before signing any contract.

Removing the window

Properly removing a window is important to keeping a safe and clean work zone and minimizing damage to the wall. 

Each window must be remeasured before anything is removed to ensure the new window will fit properly. If not, you may end up with an open hole in your home with no window to go in its place. 

Removing trim

First, the trim around a window should be removed by scoring the surrounding caulk with a sharp box cutter or tool to ensure a clean removal. Then, a scraper blade must carefully be wedged between the trim board and wall to loosen the nails to lift the board slowly. 

This is the best practice to remove the trim to minimize damage to the wall and trim boards, especially if they will be reused. 

Removing the window sash and frame

To get the entire window out, first, the sash must carefully be removed. The window sash is the part that holds the glass of the window to the movable part of a sliding window. 

For double-hung windows, the bottom sash should be removed before the top sash. This makes it easier to remove the top sash and therefore minimizes potential damage.

Once the sash or sashes are removed, the jambs around the windows must be removed. Depending on the window, a best practice is to use a hand-held blow torch to heat the sealant around the jamb and window to loosen it up. 

The installer can then maneuver the window to tilt out each panel and remove it carefully without breaking the glass. 

If these proper practices are not taken before removing the actual window, the potential for glass breakage to the old window is heightened. This makes for a messier workspace and unnecessary damages to the existing window and surrounding wall. 

After the window is entirely removed, the window frame should be inspected for rot, termite damage, or any other concerning damages that will need repair. A high-quality contractor should have the tools and skills necessary to repair minimal rot around the window frame. However, a specialist might have to be contacted to fix the wall if there is severe rot in the wall.

If there is significant damage to the frame and wall, a change order will need to be made to the contract. 

Then, the area should be cleaned and debris taken away to prep for the new window to be replaced. 

Installing the new window

Once the window is out, a high-quality contractor will remeasure the opening to ensure the window will fit. 

The replacement window should be ordered about ¼ in. smaller than the opening. This space leaves room to square the window vertically and horizontally properly.

If the new window is to the exact measurements of the opening, it will more than likely be too big in one corner and too small in another. This would not allow for the window to be leveled appropriately and overall not fit in the opening.

Before officially setting the window into place, a pan must be placed at the top and bottom of the window frame to help direct and force any water out. 

If a pan is not used, water can become trapped behind the window frame, and rot can form. 

Then, flashing tape will also be applied around the perimeter and edge of the window frame to provide another form of a weather barrier. 

Now it is time to place the window. Once the window is set in place, shims will be used between the window and frame to fill in that ¼ in. space to properly level the window. 

Shims are long, thin beams with a slight wedge to them. When put in the gap between the window and frame, the small wedge will shift the window one way or another, allowing it to be leveled correctly. 

If shims are not used, and the gap is filled with foam or caulk, it will not be leveled properly and will compromise the operability and lifetime of the window. 

The window frame is then screwed into the wall with 3.5 in. screws to secure it properly. This length ensures the screw will secure the window to the wall. Anything smaller is not recommended. 

Once the window is properly leveled, shims are in place and screwed in, an expanding foam will fill in around the window. This foam expands in between each little crack and crevice until it touches a surface. This ensures everything is sealed and tight.

The best practice is to put the exterior trim on first, then apply the expanding foam around the frame from the interior. This makes for a cleaner application and less cleanup in the end. 

The proper amount of foam must be applied. If not, then the shims will not stay in place and cause the window to fall out of square. 

Then the interior trim can be placed once the foam is dried. 

Installing the trim

When installing the trim, smaller finishing nails should be used to nail the trim to the wall. These nails will then need to be filled and smoothed with spackle to hide them. 

The trim must then be caulked around the edges and painted to finish the project. When choosing a contractor, it is important to clarify whether or not caulk and paint will be included in the window installation. 

Some contractors do not consider caulking and painting as part of the window replacement. This leaves the job either up to you or forces you to find another contractor. 

Other contractors have punch list crews that will come the day after the installation is complete to do all caulking and painting. Having a separate crew responsible for caulking and painting provides another set of eyes to inspect the window and ensure it was installed correctly.

When the caulk is applied, it must be smoothed properly immediately following the application to have a clean and finished look. An exterior caulk with a 50-year lifespan should be used. Anything less is not going to last. 

A result of a low-quality installation is if a contractor uses an interior caulk on the exterior. Interior caulk is not made to withstand weather conditions, and this will cause seal failure.

It’s also important that the proper primer and paint are used for the trim. If wood trim is not primed with the right product, it will not be sealed properly. This will allow water to infiltrate the wood and cause rot. 

After the final caulk and paint, your high-quality window replacement is complete. 

Phase 3: What does a high-quality contractor do after your window installation? 

Immediately following the installation of the last window, the entire work area should be properly cleaned. This means taking the old windows away, vacuuming any debris, and ensuring no broken glass or window parts are left. 

It is an important aspect to know how a contractor handles the cleanup and trash. Some contractors do not take away the old windows and will just leave them for you to throw away, which is a complicated, taxing chore. 

After the final caulking and painting, a high-quality contractor will make sure to go over each window and show you how to operate them properly. 

You should then be walked through your warranty for your windows and feel confident in the contractor’s work to ensure that warranty. Then you will know what to do if something breaks or goes wrong with your new windows. 

If your new windows are installed and the crew leaves with no follow-up, this can confuse you. Is the project finished? Are there any next steps? What if I have a question or problem with my window?

This is why great communication is a necessary trait in a high-quality window contractor. 

Choosing the right contractor for a high-quality window replacement

Now that you know the steps of a window replacement and what makes a high-quality versus low-quality installation, you can choose a contractor that will meet your expectations and needs for your project. 

It is important when scoping out contractors that you ask about their installation processes. Knowing the basic window installation process and asking specific questions is your best defense mechanism against a faulty project and low-quality contractor. 

At Southwest Exteriors, we aim to provide you with the highest quality service and installation for your window replacement. Because we have been in this business for over 30 years, we have perfected our processes to make a window replacement project as easy and stress-free as possible. 

Our installers are all certified in the windows they install, so you have an extra level of assurance they will install your windows correctly. 

Spotting red flags in a contractor is one of the easiest ways to save yourself from a low-quality contractor. This, in turn, will help you find the right contractor that will provide you with a high-quality window replacement. 

Want to read more about how to choose the right contractor for your project? Check out this article that outlines 13 red flags to look out for in a home remodeling contractor.