Door Sticking in Winter or Summer? How to Stop Thermal Bowing

In summer, you may notice your steel entry door sticking when you try to open or close it. In winter, when this happens, it might seem like the door has been frozen shut. This can happen, but in both cases, the likely culprit is a phenomenon called “thermal bowing.”

“Most people who’ve worked on a house before know about thermal expansion,” said Scott Cline, J&B Construction co-owner. “Things expand when they’re hot and shrink when they’re cold, especially metal. When it comes to thermal bowing, thermal expansion is typically the root of the problem.”

Bowing arises specifically in weather where the indoor temperature doesn’t match the outdoor temperature – such as when it’s cold outside and warm inside, or vice versa. The outdoor side of the door will shrink, due to the cold, while the warm indoor side expands. This causes the door to “bow,” or curve, very slightly. “The curvature is rarely visible to the naked eye, but a few fractions of an inch can cause the door to scrape or get stuck against the frame,” Scott said.

A door with a thermal break, as well as dark-colored doors, tend to bow. Thermal bowing also affects sliding doors with metal frames, or steel garage doors. The curving effect increases with the length of the door.

On entry doors, thermal bowing is usually not a structural concern. “It doesn’t mean your door is old or worn-out, or needs a replacement,” said Scott. “This is normal behavior for steel doors exposed to outdoor temperatures.”

If you’re experiencing problems, J&B has ways to resolve the situation.

One solution is to paint the outside of the door a lighter color. “Light colors reflect sunlight rather than absorb it, which will cool the surface and lessen the effects of bowing,” said Scott.
Another way would be to modify the space between the door and the frame, providing the door with more room to swing.
“Installing storm doors lowers the heat differential between the inside and outside, reducing thermal bowing in turn,” Scott said.

J&B Construction can handle your exterior and patio door needs. Visit us online or call 262-437-0537 address your door situation today.

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J & B did an amazing job from start to finish. The initial meeting at my home took place exactly at the time that was agreed upon and Scott was thorough in his explanations and transparent about costs. When the time came to begin the project, the team that showed up was friendly, professional and timely in getting the project done. The cleanup afterward was such that it looked like they hadn't been there at all. The roof looks great, there were no surprises and Scott came by to inspect the work and explain the warranty upon job completion. I would highly recommend them.

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