thanks in advance for any advice. We bought our 100-year-old house last summer, so this is our first winter in it. The walls are not insulated, so we can tell where the heat ducts run not only because of the placement of vents, but also because we can put our hands on the walls and it will feel warm if the duct is behind it. In the living room, the wall has always looked patchy in front of the duct (like patched plaster), but recently a new crack has appeared--still hairline, but it definitely wasn't there before. It runs vertically, parallel to the duct.

Is this due to the temperature difference between the cold and warm parts of the wall? Why is it just happening now after many years of this heat system being used? Should I be concerned?

  • Hello, and welcome to Home Improvement. It would help if you added a picture of the crack, but either way my guess is it's nothing. – Daniel Griscom Jan 31 at 21:56

Could it also be that the walls were patched prior to selling, and the cracks, which were already there before, resurfaced? Just as @DanielGriscom suggested, a hairline crack on an already patchy, uninsulated wall, in front of the heating pipes, points at "it's nothing".


I am in particularly the same situation. Pictures would be better. However, I'm assuming the walls are plaster, right? If so, the plaster is old. The duct work could have shifted due to straps coming loose. Its possible due to the house settling that the duct work or framing shifted as well. Thus pushing the duct tight to the wall. Possible heat/cold or moisture weakened the plaster. It could also be a patch job becoming visible again. Pictures would definitely help here.

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