cathedral ceiling insulation

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Cathedral Ceiling Insulation

Sloped, vaulted, and cathedral ceilings are different names for essentially the same ceiling configuration. These ceilings are very popular in newer homes and remodeled homes, and they certainly add dramatic visual interest to a room. But because there is little or no attic space separating inside and outside air, proper insulation is especially important.

Many cathedral ceilings will require that insulation be installed around recessed light fixtures. There are some important safety measures you should be aware of when working with insulation around light fixtures. Be sure to review the Special Considerations for the information you need to complete the installation without creating potential fire hazards.

It's also a good idea to wear a work helmet when you're installing ceiling insulation. This can help you avoid injuring yourself on exposed framing members such as ceiling joists, exposed nails and other hazards.

To make your cathedral ceiling insulation job easier, Johns Manville makes special high-performance R-value insulation designed specifically for cathedral ceilings.


How to Insulate Your Cathedral Ceiling

  1. Caulk where wiring runs through the ceiling joists and around the top of the wall.
  2. Staple prefabricated vent chutes between joists with one end over the wall top plate. Vent chutes ensure there is at least 1" of space between the roof sheathing and insulation, allowing vapor water to flow out and to cool the roof. Depending on your house, vent chutes may be placed only at the soffit areas or run all the way up to the ridge line.
  3. If you're using unfaced insulation, place it between the joists and gently press into position allowing friction to hold it in place. Insulation should be expanded to its full thickness in the cavity to extend over the top of the framing or trusses to insure complete coverage. However, avoid compressing the insulation material, because compression will reduce its R-value.
  4. If you're using faced insulation, press it between the ceiling joists with the vapor retarder face down toward the room, unless building codes specify otherwise. Hold the insulation up with one hand while stapling the flanges to the joists on both sides every 6" - 8" with the other hand. Be sure to keep insulation three inches away from recessed lighting fixtures, unless the fixture is IC rated. Also, make sure the insulation is installed at least 3" away from any metal chimneys, gas water heater flues or other heat-generating sources.

Related Products

ComfortTherm® Batts and Rolls


ComfortTherm® insulation is a lightweight, thermal and acoustical insulation made of long, resilient glass fibers bonded with an acrylic thermosetting Formaldehyde-free™ binder.

Kraft-Faced Batts and Rolls


JM's Kraft-Faced Batts & Rolls are made of naturally white, Formaldehyde-free™ fiber glass, reducing environmental concerns including the risks of poor indoor air quality and the effects of manufacturing on the environment.

Unfaced Batts and Rolls


JM's Unfaced Insulation is a lightweight thermal and acoustical fiber glass insulation made of long, resilient glass fibers bonded with an acrylic thermosetting resin made without formaldehyde.

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