How to Seal Windows and Reduce Energy Bills This Winter

Poorly sealed windows allow heat to enter your home during the summer and cool drafts during the winter. As a result, your HVAC unit works overtime to maintain your desired temperature, leading to high energy bills. Here, we explain how to seal windows with various materials and methods including caulk, weather stripping, plastic shrink-wrap, and draft stoppers.

How to Seal Windows

While replacing your windows with new energy-efficient ones is the most effective way to stop the draft and lower your utility bill, it's not always an option. Luckily, there are several ways to seal your existing windows to help prevent air transfer between the interior and exterior.

Caulk Around the Windows

Caulking around windows is sometimes all it takes to reduce their draftiness. It's also one of the most cost-effective ways to seal a window, as caulk is relatively inexpensive.

Caulk is ideal for filling small cracks around various window components. It can create a watertight and airtight seal that remains flexible for years after application. This flexibility ensures the caulk's seal won't crack due to natural expansion and contraction.

If your window has gaps larger than 1/2 inch, caulk may not work well. If these gaps are deep, expanding foam insulation designed for window and door use may be necessary to fill the cavity. Once the foam is fully expanded, you can trim it flush using a sharp knife and cover it using a wood trim piece or a bead of caulk, whichever is more appropriate for your window.

Install Weather Stripping

Weather stripping is useful for sealing around the moving components of a window, such as beneath a moving sash. Whereas caulk will seal the joint, weather stripping allows you to open and close the window, sealing the gap tightly once the window is closed.

Most foam weather stripping has one sticky side so it can be adhered to the fixed portion of the window without sticking to the moving one. To promote a strong bond between the foam weather stripping and the window sash, remove dust or debris, thoroughly clean the window with a degreaser, and dry the surface.

Seal with Plastic Shrink-Wrap

To create a temporary airtight seal around your window, look for plastic shrink-wrap window insulating kits, which include double-stick tape and sheets of plastic shrink-wrap.

To seal a window using plastic shrink-wrap, follow these steps:

1. Clean the window.
2. Apply strips of double-stick tape on all four sides of the window frame.
3. Cut the plastic sheeting slightly larger than the window pane. Place it on the pane, pressing it against the double-stick tape to secure it.
4. Use a hairdryer or a heat gun on low to shrink the plastic, starting on the perimeter and moving across the shrink-wrap until it's perfectly taut.
5. Clean up the excess plastic using a utility knife.

Insert Draft Stoppers

Store-bought draft stoppers can be great for stopping drafts with minimal effort and without altering the window. There are various styles of draft stoppers tailored for different types of windows and doors.

Many draft stoppers include two tubes that can be cut to the window's width and then slid inside a piece of fabric. The fabric is then slid beneath the window sash. Once the window is closed, the two tubes are tightly held on each side of the window. While this style of draft stopper can be effective for windows, they are often used on doors.

A more effective style of a window draft stopper is designed to stick along the bottom edge of the window sash. Once the sash is closed, the overhanging rubber material compresses against the window frame to prevent airflow.

The most effortless style of draft stopper that can be used to reduce a window draft looks like a long pillow. You simply lay it at the bottom of the window to block the draft.

How to Identify a Drafty Window

If the source of your window draft isn't obvious (such as a visible crack), it can be hard to pinpoint where the issue lies. Here are some useful ways to identify a window draft.

• Turn off any fans and other air movers. You may have difficulty identifying your draft because air is moving from sources like fans, dehumidifiers, HVAC systems, and more.
• Light a candle and place it next to the window. Blow the candle out and watch the smoke. The candle smoke will blow if it's positioned near the draft. This method may take a few tries and it can be helpful to trace the window's border with the candle.
• Some lightweight curtains will move when blown by a window draft.
• Drafty windows are prone to condensation buildup. If you have just one window with condensation on it, there's a good chance it's the source of the draft.

Source: Kamron Sanders, BHG.com