Attic Doors

[aaronm]

In a single-family residence is a door leading from a conditioned space into a unconditioned ventilated attic required to be solid core or hollow care and insulated or uninsulated? Assuming required compliance with 2006 IRC and 2006 NEC and in either zone 2 or 3, what are the applicable codes?

[Jerry Peck - Codeman]

Hi Arron,

The wording in the IRC is vague on the requirements for 'attic' insulation in that it specifies 'ceiling' R-value requirements with the implication that it is referring to 'ceiling/attic' insulation, when it is in reality referring to insulation separating the 'attic' from the thermal envelope of the structure.

If we keep in mind that the intent is to insulate (and thus separate) the 'attic' from thermal envelope of the structure, then it also can be presumed that the intent is that this insulation is applicable to all surfaces which adjoin the attic, i.e, attic access hatches, attic access door, attic-ceiling surfaces, and attic-wall surfaces.

If the surface adjoins the attic then the required attic insulation R-value applies to that surface.

Thus, in your example, there is a door in a wall which opens to the attic, and (presumably) the attic floor is the ceiling to a portion of the thermal envelope of the house, thus the attic floor (ceiling to the space below) will require R-30 insulation, likewise the wall (and its opening - the door) to that attic also requires the same R-30 insulation.

Treating the door insulation R-value as being the same as the wall insulation R-value is the same as requiring the an attic access opening cover to have the same insulation R-value as required for the rest of the ceiling with the attic space above it - and that is presumed and done all the time.

[aaronm]

Along the same line of reasoning then I assume that a hollow core door would not suffice.

[Jerry Peck - Codeman]

[aaronm]

It was my understanding, from the IECC, that the attic is the exterior of the building envelope and thus the exterior of the house. Would that not make any door to that area an exterior door?

[Jerry Peck - Codeman]