How to choose and install storm windows

5 min read

According to the U.S. Department of Energy, leaky windows can account for 10–25% of your heating bill. If your windows are in good shape—or if you’re on a tight budget—adding storm windows is far more affordable than replacing the windows.

Installing storm windows

Watch this video to learn the basics of installing a storm window. Explore different ways to repair and improve drafty windows.

Types of storm windows

Traditional storm windows go on the exterior of your house, and interior storm windows are installed on the inside of your primary windows. Either type will add extra wind protection and weather insulation to your home. Any storm window (including low-E) can be custom-ordered to fit over your current windows. If your windows are in standard sizes, you may be able to buy stock storms.

Low-E storm windows

Low-E (low emissivity) storm windows have an ultra-thin, nearly invisible coating of metal. The metal reflects heat back to its source, keeping your home warmer and saving you energy and money. Like all other storm windows, low-E storms create an insulating air layer between the storm and the existing window, while also reducing how much outside air can seep in. As an added benefit, the low-E window coating limits damage from ultraviolet rays, reducing color fading on window treatments, floors, and furniture.

Steps to install an exterior storm window
  1. Measure the window
    • Measure the opening width at three locations - top, center, and bottom
    • Measure the opening height on the right, left, and in the center
    • If the measurements differ, use the smallest of the three when ordering a new storm window.
    • Both stock and custom sizes are available at local retailers
  2. Prep the window opening
    • You may need to scrape off some old paint.
  3. Caulk around the sides and top of the opening before you screw the window into place.
    • Exterior storm windows are designed with holes at the bottom to allow water or condensation to drain so do not caulk the bottom.
  4. Check that the window is square and install following the manufacturer’s instructions. Alternatively, follow these step-by-step instructions from the U.S. Department of Energy.
  5. Adjust the expander on the bottom of the window so it’s tight against the windowsill.
Important considerations
  • A good short-term solution are window insulation kits that come with weather-stripping and plastic film that can be installed with a hair dryer to create a tight seal.
  • Window insulation kits, weather stripping, and Low-E storm windows can be found at your local home improvement store.
  • If you have old windows with cracked glass or rotted frames that require a lot of maintenance and are in total disrepair, replacing them with new high performance windows is probably a good idea.
  • There are non-energy benefits to replacing your windows, such as improved property value and ease of use, but the cost of new windows will not likely be offset by energy savings alone.