I have hot water baseboard pipes running along the inside of the knee wall attic behind my second floor bedrooms. They are covered with old pipe foam sleeves. The knee wall is insulated as a conditioned space; rafters have faced batts.

To add extra insulation is it ok to cover the pipes with extra unfaced batts (r30) that i have from a recent attic insulation project? I just want to ensure that any heat doesn't escape from the pipes...

1 Answer 1


There's no concern unless there's moisture present. Fiberglass presents more of a mold trap than closed-cell foam.

Keep in mind that you'd have to wrap the pipes carefully enough that no airflow can move around the insulation. In other words, just laying batts over the pipe does little if the ends of the run are open to the air.

You might partially split the batt (think hotdog bun), slide it in place, and press the batt back together to create something of a seal.

  • Thanks for the reply... my only concern for doing this is to prevent any hot air from escaping the pipe insulation and warming the area..... possibly the snow pack on the roof. I just put new shingles on the roof and want to keep them as strong as possible.
    – Bob
    Oct 11, 2019 at 15:22
  • Your primary concern should be energy efficiency. If you have ice dam issues, ventilation is the solution.
    – isherwood
    Oct 11, 2019 at 15:26
  • 1
    I agree... we don't have any ice dam issues. The house is a saltbox colonial and there is no ventilation possible is this space behind the bedroom wall. Homes in this area were built without soffit ventilation for the main attic; only gable end vents and a ridge vent. The knee wall space has no vent possible by design. I don't care for this set up and am trying to prevent any problems.
    – Bob
    Oct 11, 2019 at 15:32

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