What is the definition of an attic

[gacinaz]

I continue to run into building officials who want to treat vaulted ceiling and attics differently. Specifically with regard to venting. Is there an actual code definition of an attic? Is there a different definition for the space between the ceiling and the roof of a vaulted ceiling?

[Jerry Peck - Codeman]

I continue to run into building officials who want to treat vaulted ceiling and attics differently. Specifically with regard to venting.

Differently in what way regarding venting?

Is there an actual code definition of an attic?

Not knowing what state you are in, here is the 2006 IRC definition of what an attic is:
- ATTIC. The unfinished space between the ceiling joists of the top story and the roof rafters.

Is there a different definition for the space between the ceiling and the roof of a vaulted ceiling?

That is still called "the attic", however, by definition, if the vaulted ceiling framing is nothing more than "rafters", say 2 x 12 rafters, then there are no "ceiling joists" and therefore no "attic" as specified in the definition.

However, regarding ventilation, those two types of construction are addressed as one and the same.

From the 2006 IRC. (underlining and bold are mine)
- SECTION R806
- - ROOF VENTILATION
- - - R806.1 Ventilation required. Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow. Ventilating openings shall be provided with corrosion-resistant wire mesh, with 1/8 inch (3.2 mm) minimum to 1/4 inch (6 mm) maximum openings.

That means that "Enclosed attics" "and" "enclosed spaces formed where ceilings are applied directly to the underside of roof rafters" "shall" be treated the same and ventilated in accordance with the above section and the sections which follow it which address roof ventilation.