It has been YEARS since I have dealt with a thermal bow problem, although I think about it whenever I pass close to a metal door painted a dark color and can feel the heat radiating from it on a sunny day. I actually remember the first time I received a call about a door that was binding so much that it could not be opened during the day, but would magically work properly at night. Was I really supposed to tell the GC that the door needed to be painted a different color? This was probably around 1987, and yes – I realize that some of you were not born yet! For what it’s worth, I was only 20. 🙂
What reminded me of thermal bow was a post about this topic on the LaForce blog. In part, the post reads:
Thermal bowing is a temporary condition that can occur on exterior metal doors when the temperature is vastly different on one side, compared to the other. Thermal bowing will normally occur when one side of a door is too hot, but it can occur in reverse, under extremely cold conditions. When there is a large temperature difference, the exposed surface of the door can swell/expand on the heated side, causing the door to bow. When the temperature has reduced and is no longer at an extreme difference, the bowed door will return to its normal form.
According to the Allegion Knowledge Center the typical symptoms of thermal bow are:
- Door will bow toward the sun or exterior of the building
- Hardware latching and unlatching difficulties
- Door clearances may be very tight at the top and bottom of the door
And the ways to alleviate the condition are:
- Painting the surface of door a lighter color
- Selecting a door with a core construction that is less susceptible to thermal bow – honeycomb and steel-stiffened doors are the least susceptible
- Installing an awning to block direct sunlight exposure on the door surface
If the door is binding at all times of the day and night, it’s likely that the problem is related to improper installation of the frame or a problem with the gasketing or the latching hardware. If the problem occurs on sunny days, and disappears at night, it’s probably thermal bow.