What difference is a particular window attachment going to make to the comfort of your home? How effective is a magnetic seal or compression seal when used on a storm window? We’ll answer these questions in this blog and why Indow decided against magnetic window insulation.


Why We Said No to Magnetic Seal


When Indow first designed our window inserts, we considered putting magnets inside our compression tube, but we found that a magnetic window insulation created a lot of design flaws.

“It’s not very attractive, it’s cumbersome to install, and that metal frame remains in your window frame after you remove the insert and that’s ugly. So there were three things we didn’t like about the magnetic system.”

-Sam Pardue, Indow Founder

First, for a magnetic seal to form, magnets have to grab hold of something. That something is permanently attached to your window frame—generally a metal bracket fixed to the entire window frame needing many holes drilled into it. So it’s cumbersome to install.

Second, magnetic window insulation is not attractive either with the window insert installed or removed. If you take the window insert off, you still have a big metal bracket surrounding your window.

diagram of a magnetic window insulation system

Third, the acrylic used in most window inserts expands and contracts with the temperature. While the window insert and attached magnets move, the metal frame does not. So, whatever magnetic seal there was is broken and the whole panel can pop off.

Magnets attract in one direction, but compression tube creates spring force all the way around the window frame. It absorbs expansion and contraction in every direction and creates friction and resistance against air pressure.

So, we removed the magnet and created a window insert that relies on compression seal alone. The compression tube can do everything we need and the simplest solution is often the best solution.

woman installing Indow insert in window to create compression seal

Why Compression Seal is Better Than Magnetic Seal


The compression tube around our acrylic panels is the spring force that holds in insert in place. It absorbs all thermal expansion caused by temperature change. This ability to expand and contract creates a near airtight seal no matter the shape, size, or condition of your window. The compression tube is a seal against drafts and heat, and it keeps conditioned air inside.

close up of Indow window insert creating compression seal

A compression seal is stronger than a magnetic seal because it is better at dealing with out of square windows. If your home is older and has had time to settle, it most likely hasn’t settled perfectly straight – this causes out of square windows.

“The problem is that magnetic systems don’t always deal really easily with the fact that most window frames are really out of square. So sometimes you get a gap up in the corner, if it’s a really out of square window. With our system we’re going to make the insert the exact shape of the window opening, you’re going to get very tight seal all the way around—a nice even compression.”

Sam Pardue, Indow Founder

Magnetic seals can get gaps because they were made for a perfectly square window frame. Compression seal adjusts for the out of square window so you continue to have a tight seal and even compression.

Our compression seal can accommodate expansion and contraction from heat and window frame inconsistencies without altering the window at all. Our compression seal is stronger than magnetic seal, fits any shape of window, and requires no hardware.

For more information read about our compression system.