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You are here: Home / Archives for Cathedral Ceilings

Cathedral Ceilings

Best Approach to Hot-Climate Cathedral Ceiling

April 3, 2024 by buildingadvisor 1 Comment

Use of vapor diffusion port in hot climate cathedral ceiling.

Q: I have an unfinished space above our garage that we are converting into a flex space.  It has a cathedral ceiling.  We are in Houston, TX  so I am concerned about the heat and humidity in the space.  The west side of the space is sloping roof with soffit and gable vents along the entire length, so creating a baffle out of rigid foam is simple.  We have knee walls with … [Read more...] about Best Approach to Hot-Climate Cathedral Ceiling

Combining Foam & Fiber Insulation in Cathedral Ceiling (Flash & Batt)

August 23, 2022 by buildingadvisor 20 Comments

Flash and batt approach to insulating unvented cathedral ceiling

Q: I am renovating and old home with an uninsulated, non-vented walk up attic built in 1848. The shingle roof is less than 10 years old. The simple gable roof has 2x6 rafters. I’d like to apply 2 in. of closed-cell foam and then install 3 ½ in. of R-15 rockwool and add an Intello “smart” vapor retarder. The finished ceiling will be1/2” nickel gap shiplap. Will this approach … [Read more...] about Combining Foam & Fiber Insulation in Cathedral Ceiling (Flash & Batt)

How to Prevent Condensation in Cathedral Ceiling?

December 30, 2020 by buildingadvisor 30 Comments

Typical detail insulation and ventilation cathedral ceilings

Q: I’m currently dealing with insulating a cathedral ceiling, which has become a major issue. I’ve been researching solutions but feel stuck in figuring out what’s the best way to go about dealing with the problem. I have a shed roof with 2:12 pitch, built with 2x8 roof joists. It’s a mobile home that’s 14x76, so the roof is just one continuous slope. I live in northern … [Read more...] about How to Prevent Condensation in Cathedral Ceiling?

Insulating A Cathedral Ceiling With Foam Board

May 30, 2020 by buildingadvisor 32 Comments

Foil-faced iso-board is effect attic insulation

Q: What is the best way to insulate an unvented cathedral ceiling in a detached workshop? I plan to insulate before installing an AC and heating system (thinking mini-split). Is closed-cell spray foam the best, or only, good option in this case? I don't plan on finishing the space with drywall, although wouldn't rule it out in the future. .And given that it's only a workshop … [Read more...] about Insulating A Cathedral Ceiling With Foam Board

Air-Sealing An Unvented Cathedral Ceiling

June 25, 2018 by buildingadvisor 6 Comments

Q: We live in Kingston, NY and cathedral ceilinged the main living space of our 1925 raised ranch. The rafters are 2×6's. we used R-21 fiberglass batts (5 1/2 " thick) and 1" pine tongue and groove boards. The roof is an unvented shingle roof. Is there an affordable solution to prevent humidity build up? – Kate A: In cold climates, unvented roof cavities can lead to moisture … [Read more...] about Air-Sealing An Unvented Cathedral Ceiling

Spray Foam For Unvented Cathedral Ceilings

August 20, 2015 by buildingadvisor 51 Comments

Polyurethane spray foam seals and insulates an unvented cathedral ceiling, also called a "hot roof".

John asks: Is it better to use Icynene (open-cell) or closed-cell spray foam in an unvented cathedral ceiling? We are building a new home in Atlanta, GA. Steve Bliss, of BuildingAdvisor.com, responds: I don't really like unvented cathedral ceilings, also called "hot roofs", because they are very unforgiving. If the roof sheathing or rafters ever gets wet from a roof leak, or … [Read more...] about Spray Foam For Unvented Cathedral Ceilings

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