How Big Should An Attic Access Be

The 2012 international residential code requires an attic access opening for attics with an area greater than 30 square feet and a vertical height in excess of 30 inches.
How big should an attic access be. Mark each joist location with a pencil. The rough opening cannot be less than 22 inches by 30 inches and must be located in a hallway or other readily accessible location. What is the minimum size for attic access opening. The minimum size for an attic s access building codes.
Your joists should be 16 to 24 inches on center. But venting has an equally important. Select a closet ceiling or hallway ceiling with good floor space underneath since you will need to use a ladder to access your attic. If there is no vapor barrier double it to one square foot of nfa for every 150 square feet of attic floor space half for intake half for exhaust.
Move a stud finder across your ceiling to locate the joists. A inch gap around the perimeter of a standard pull down staircase can potentially leak the same amount of. Tuesday january 28 2020. If the opening is located in a wall the 30 inch dimension must be vertical.
The purpose of attic ventilation is obvious in the summer when hot air collects in the attic and makes the entire house uncomfortable. Vent size for an attic. Also to find out where your home might be losing energy consider conducting an energy audit. The attic may be accessed through a scuttle door or attic hatch usually located in a closet or main hallway.
If the access is located in the ceiling the minimum unobstructed headrom above the opening must be 30 inches measured vertically at some point over the access. This generally comes in 7 lengths and you will need three pieces of it for a standard sized attic access hatch. If your attic floor has a vapor barrier you will need one square foot of nfa per every 300 square feet of attic floor area half of that will be intake half for exhaust. A home s attic access such as an attic hatch pull down stairs or knee wall door often goes uninsulated and unsealed creating one of the biggest holes in the thermal and air barrier between the attic and conditioned space.
According to the 2006 international residential code r807 1 attic access homes with combustible.