Both types of storm windows – interior and exterior – help with window insulation and energy efficiency. They add a layer to your window to help regulate temperature, damp noise, and protect your existing window. If you’re still considering replacement windows, read our comparison: Storm Windows vs Replacement Windows.
Interior and exterior windows have a lot of similarities. It’s in understanding their differences, such as inside window insulation, that will help you decide which is best for your home or building.
There are many storm window styles. Which storm window style you choose depends on: your home, existing windows, and what issues you are dealing with.
Exterior: Glass panels surrounded by wood or aluminum frame. These attach to the outside of your window frame using screws, caulk, or hinges. Sometimes the frame is semi-permanent so the pane will be released by swivel pins for cleaning or replacement while the frame stays attached to the house. Most have weep holes so accumulated moisture can evaporate.
Metal & Glass
Wood & Glass
Plastic & Glass
Interior: Interior storm windows are panels made of glass, vinyl, or acrylic surrounded by a frame of wood, metal, plastic, tape, or rubber. They attach to the inside of your window frame through magnets, adhesive, a track system, or compression system.
Silicone & Acrylic
Metal Foam & Acrylic
Plastic & Acrylic
Interior storm window benefits: Invisible from the outside, no weep holes for higher efficiency
Exterior: Exterior storm windows protect your windows and increase energy efficiency. Because of their weep holes, they cannot achieve a near airtight seal. This means they cannot stop all air and noise from getting in (where air goes, noise goes).
Interior: Interior storm windows can create a near airtight seal with very little air leaking through. Many are custom made to fit your window snugly (which means non-standard shapes a no problem), blocking air from entering or exiting. This helps with window soundproofing. The dead air space created between the window and insert adds to insulation and soundproofing.
Interior storm window benefits: Inside window insulation via dead air space, snug fit, custom shapes
Video: Do Storm Windows Help Insulate?
Exterior: Exterior storm windows can interfere with curbside appeal as they are always visible and can obscure shutters, sashes, casing—all meant to provide 3D effect and add character. They can sometimes be painted to match home’s exterior. Exterior storm windows are used to preserve old windows, but detract from the home’s face by covering up details that make it interesting.
Interior: You cannot see most interior storm windows from the outside. Some you can notice from the inside, others disappear once they are in place. Is interior design important to you? Get interior window inserts that insulate your home while maintaining your aesthetic.
Interior storm window benefits: Doesn’t change home’s appearance
Exterior: Exterior storm windows can be medium to difficult to install. There’s no need for carpentry skills (unless you build them yourself), but there is need for a ladder unless your windows are basement or low to the ground. You will also need some hardware and tools. They have permanent to semi-permanent application. To maintain, you’ll need to climb that ladder again and use tools.
Interior: Interior storm windows can be installed without leaving your house. Some require semi-permanent hardware and tools to install. Some just push into place and can be removed and reinstalled easily.
Interior storm window benefits: Can be quickly installed and removed
Cost for both exterior and interior storm windows depends on:
- Construction & materials
- How much maintenance you want to put into it
- If they are historically accurate
- How long they last
- If they are custom made for you windows
The best storm windows will take a larger investment upfront, but will have a higher and quicker return on investment. Also, look at how long each storm window will last. One may cost less upfront, but would need to be replaced every few years.
For an average window, including labor and supplies, each type costs:
Exterior storm windows: $164 – $287
Indow window inserts: $360 – $468
Traditional wood storm windows: $525 – $577
Indow is AERC certified. AERC, the Attachments Energy Rating Council, is an unaffiliated organization that rates window attachment products on energy efficiency by measuring various factors such as Air Leakage (AL) and U-Factor.
On air leakage, Indow scored in the top two out of 33 storm windows tested, 11 of which were interior storm windows. U-Factor is an indicator of heat transfer through a surface. It tells you how well a window product insulates. Indow inserts have a U-Factor of .3, making them a top performer on insulation among all available storm windows. Indow inserts are your solution for comfort, quiet, and energy savings.
Indow inserts provide instant comfort once they reach your windows. Now you can get an instant estimate in 3 easy steps.
Measure At Home
See Your Estimate
We still check your measurements and provide accurate results down to the 1/32″, but this estimate is the first step in finding instant comfort.