How To Replace a Basement Window

Replacing an old basement window can improve your home’s energy efficiency and overall comfort. This project is possible for many DIYers, so we’ll walk you through replacing a basement window, from removing the old window to installing and sealing the new one. This Old House general contractor, Tom Silva, demonstrates the steps to replace a basement window, offering insight for homeowners tackling this project.

Understanding Basement Windows

Basement windows affect your home’s functionality and comfort. They provide natural light and ventilation and can, in some cases, serve as emergency exits. However, older windows can have issues, including drafts, leaks, or deterioration, making replacement necessary.

Types of Basement Windows

There are several types of basement windows, each with its own benefits. Egress windows are required by building codes in many areas since they’re larger and provide an emergency exit. Glass block windows are not openable, but they offer privacy and security. Hopper windows open inward from the top and are more compact. Sliding windows suit wider openings as they slide horizontally to open.

Signs It’s Time To Replace Your Basement Window

If you notice condensation between glass panes, drafts, visible damage or rot, water leaks, or any difficulty opening or closing your window, you likely need a window replacement. Recognizing these signs early can prevent more severe damage to your home’s foundation and interior.

Preparing for Basement Window Replacement

Before diving into the replacement process, proper preparation is key for a smooth project.

Tools and Materials Needed

Gather the following tools and materials before starting:

• Caulk gun
• Cold chisel
• Drill/driver
• Exterior-grade caulk
• Exterior-grade primer and paint
• Expandable urethane foam
• Hammer
• New basement window
• Reciprocating saw
• Screws
• Shims
• Tape measure
• Utility knife
• Whisk broom

Measuring for Your New Window

Accurate measurements are necessary for a proper fit. Measure the width and height of the existing window opening at multiple points, as older openings may not be perfectly square. Use the smallest measurements so that your new window will fit. Measure twice to double-check your accuracy. A properly-sized window will prevent drafts and leaks for better insulation and comfort.

Steps To Replace a Basement Window

Follow these steps to replace your basement window successfully:

1. Remove the sash from the existing basement window.
2. Use a reciprocating saw to cut through the old window frame.
3. Pull out the old window frame from the wall opening.
4. If necessary, use a hammer and cold chisel to chip away mortar from the sides of the opening.
5. Slide the new window into the opening.
6. Use shims to center the new window in the opening.
7. Secure the window by screwing up through its frame and into the mudsill.
8. From the outside, apply caulk along the sides and top of the window frame.
9. Spray urethane foam under the sill to seal the bottom of the window.
10. Apply a coat of exterior-grade primer to all bare wood window parts, followed by two paint topcoats.

Removing the Old Window

The first step in the replacement process is removing the old window. This can be tricky, especially in older homes with settled foundations. Use a reciprocating saw to cut through the old frame carefully without damaging the surrounding structure. This step can be labor-intensive, so having someone help you can make the process easier and quicker.

Installing the New Window

Once the old window is removed, it’s time to install the new one. Slide the new window into place, checking that it’s properly aligned. Use shims to level and center the window in the opening for a snug fit to prevent air and water leaks. Careful alignment of the new window provides good insulation and reduces stress on the frame.

Sealing and Finishing

Proper sealing will prevent drafts and water leaks while also improving energy efficiency. Apply a bead of butyl caulk around the perimeter of the window. This caulk helps because of its rubbery texture and ability to remain soft. Use expandable urethane foam to secure the window and provide extra insulation.

Tips for a Successful Basement Window Replacement

So your basement window replacement project can go smoothly, choose a dry day to avoid moisture issues, and consider upgrading to an energy-efficient window for better insulation. Paint or finish the new window promptly to protect it from the elements, and check local building codes for compliance, especially if you’re installing an egress window.

Common Challenges and Solutions

While replacing a basement window is a manageable DIY project, you may encounter challenges, such as uneven openings, water drainage issues, and rot or damage.

Dealing With Uneven Openings

Older homes often settle over time, resulting in uneven window openings. To address this, use shims to level the new window and fill any gaps with expandable foam before caulking to get a tight and secure fit.

Addressing Water Drainage

Proper water drainage helps prevent leaks and rotting. To properly drain water and rainfall, slope the ground away from the foundation wherever you install a new window. This will also manage water runoff, protecting your home’s foundation.

Handling Unexpected Rot or Damage

If you notice rot or damage in the surrounding structure while removing your old window, address these issues before installing the new window. This may involve replacing damaged wood or treating the area to prevent future problems. These fixes will provide you with a more secure and durable window.

Maintenance Tips for New Basement Windows

After replacing your basement window, you need to know how to maintain it properly to extend its lifespan and prevent damage. Proper maintenance involves regular inspections, cleaning, and timely repairs.

Regular Inspections

Regularly inspect your basement window for signs of damage or wear and tear. Check the seals, frame, and glass for any issues. Early detection can prevent minor problems from becoming major repairs.

Cleaning

Keep your basement window clean to allow light to enter and prevent dirt buildup. Use a mild detergent and water to clean the glass, frame, and seals. Avoid using harsh chemicals that could damage the window materials.

Seasonal Maintenance

Perform seasonal maintenance so your window remains in good condition throughout the year. For example, check for drafts in the winter and ensure the seals are intact. In the spring, inspect for any damage caused by winter weather and make necessary repairs. By following these maintenance tips, you can extend the life of your new basement window and keep it in good working condition.