I need to make a diffuser to an existing 22 x 30 skylight shaft. A flush mount of some kind would be my first choice. My goal is to keep heated air from going into the shaft instead of the bathroom.

  • This is in inches, correct? How tall is the shaft? Jan 12, 2016 at 22:40
  • As an experiment, you could use the standard window heat-shrink insulation, which is attached to the edges by removable double-faced tape. 3M is the big brand, but there are off-brand versions as well. Jan 12, 2016 at 22:44
  • Just thinking about warm wet air in the bathroom and, if sealed cold air above causing condensation on the diffuser. Something to think about with this project.
    – Ed Beal
    Jan 14, 2016 at 23:21

1 Answer 1


A standard recessed ceiling diffuser (for a 48" light) would work if you installed a divider to support the middle section for two.

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