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Community and Q&A

Retrofitting an insulated flat ceiling in a room with an existing cathedral ceiling

GBA Editor | Posted in Green Building Techniques on

We’re looking at 10 yr old tract houses to remodel and live in. But we hate the cathedralized ceilings which show up even in houses of 1700 s.f. — a local builder fad at the time. First, I know cathedrals aren’t good for energy efficiency with 4-6” of glass batts and no air sealing. Second, they may look grand in a big house but in a small living room or 12×12 bedroom they feel like an elevator shaft. We don’t like them … but the houses are cheap enough to think about.

So my wife came up with an idea, and I’m asking if it would be reasonable (improve energy efficiency w/o major expense) to lower the ceiling. Instead of a ceiling that peaks at approx 18 feet, we could attach new ceiling rafters for a 10 ft. ceiling to the structural, pitched rafters, then insulate and seal the new gypsum for the finished ceiling. My thought would be to use blown cellulose to R40+ as we upgrade the sealing and insulation of the rest of the (flat ceilinged) house as well.

The walls are usually 8 ft, so the new ceiling would leave a pitched surface approx. 30” (wall to new ceiling) which could be sealed and finished with interior rigid foam board and gypsum.

Is this reasonable? Am I once again missing a whole raft of “unintended consequences”? Would the cathedralized gypsum and insulation need to be removed for some reason?

Thanks for your opinions in advance.

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  1. GBA Editor
    Martin Holladay | | #1

    Q. "Is this reasonable?"

    A. Sure. Just pay attention to air barrier continuity and thermal barrier continuity, and be sure that the sections of insulated sloped roof have enough insulation -- at least equal to minimum code requirements.

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