Typically difficult to insulate well with traditional insulation, homes with cathedral ceilings do not have the advantage of an attic acting as a buffer between occupied space and the outside. Using spray foam on cathedral ceilings addresses common problems found with other insulation types.
Because of its air sealing properties, spray foam in cathedral ceilings curbs a “stack effect” where heated air escapes through the ceiling and roof and is replaced in lower levels of the home by drawn-in, outdoor air. Homes with cathedral ceilings equipped with foam insulation can minimize the potential of moisture or roof damage from ice damming as well as associated moisture problems. Constructing the cathedral ceiling with a vented air space allows roof sheathing to dry more easily if needed.
Cathedral ceiling code references
Unvented enclosed rafter assemblies
- Local codes based on IRC 2009: Section R806.4
- Local codes based on IRC 2012 and 2015: Section R806.5
Roof ventilation (vented cathedral ceiling)
- Local codes based on IRC 2009, 2012 and 2015: Section R806.1
- Foam plastic (spray foam)
- Local codes based on IRC 2009, 2012 and 2015: Section R316
Energy efficiency of building thermal envelope
- Local codes based on IRC 2009, 2012 and 2015: Section N1102
* R means resistance to heat flow. The higher the R-value, the greater the insulating power. Compare insulation R-values before you buy. There are other factors to consider. The amount of insulation you need depends mainly on the climate you live in. Also, your fuel savings from insulation will depend upon the climate, the type and size of your house, the amount of insulation already in your house, and your fuel use patterns and family size. If you buy too much insulation, it will cost you more than what you'll save on fuel. To get the marked R-value, it is essential that this insulation be installed properly.
^ Savings vary. Find out why in the seller's fact sheet on R-values. Higher R-values mean greater insulating power.