If I'm reading it right, current code calls for access to the attic, even if the space isn't being used. There certainly needs to be some access for wiring, etc. I plan to put in a set of pull-down stairs somewhere in the house. How do you work this with the massive amount of insulation now called for? Code minimum now would call for 12" of cellulose, for example. I can see creating a dam to secure the insulation, but how do you insulate the hatch itself to anywhere near the same degree? And I expect the hatch will get a layer of wind-shifted cellulose on it, presenting the user with a dust bath when you pull it down. Even if you could control the dust, wouldn't the hatch present a hot/cold spot in an otherwise well-insulated ceiling?

Just moved into our new ICF house in Ottawa, I put the hatch in the garage! John

Google on attic hatchway insulation. There is at least one product that provides a zip-closure bag type of access, with decent R value to it, and which provides air leakage sealing. There are other ways of building your own insulated hatchway with rigid foam, with a loose insulation dam around the opening. Make the hatch cover absolutely tight. Unless you have some sort of air seal system above the hatch door, your typical fold-down stairway doesn't seal well against air leakage. JH's suggestion to put the access out in the garage is good advice, provided you have an attached garage with common attic space. I did that on my house, as I didn't want an access hatch inside the living space. However, access from the garage means you need a fire-rated one. Another option is to provide a door on a gable end of the roof, to be accessed by ladder from outside. This presumes you don't have a hip roof.

You shouldn't really have wind-washing of loose cellulose in the attic, assuming you have insulation dams inside the soffits. Simple plywood dams sufficiently high around the attic hatchway should be sufficient.

Does anyone know what the required access opening size must be? I might have enough to slither through from the garage, but the garage and roof are dropped down from the house, limiting the size of the opening. I could also possibly place an access from the garage roof on the outside of the gable, depending upon how big it has to be. The other gable end is too prominent to have such an opening. It would be great if I could avoid a ceiling penetration altogether.

2006 International Residential Code requires a rough framed opening of 22"x30", with 30" minimum attic headroom above the access opening

The purpose of the opening is for fire fighting purposes and the size is dictated by a fire fighter with an air pack. Slithering is not a good idea nor is it legal. For the pull down stair the best solution I've seen is a fabricated inverted box of rigid foam that sits over the opening. Air sealing the bottom edge is not easy but perhaps a thick foam gasket would do it.....

The standard pull down stairs have a fairly low profile but when you get into the ones with the smaller RO the folded stair becomes quite tall requiring a large box.

a fabricated inverted box of rigid foam that sits over the opening. Air sealing the bottom edge is not easy but perhaps a thick foam gasket would do it..

This is exactly what I have. It also has some particle board on top to weigh it down - XPS foam alone doesn't have enough weight to get a good seal on gaskets. I suppose that a hinge on the side would make it even better.

According to my drawings, if I made a 30" wide opening from the garage to the main attic, it would be 26" tall as a rectangle, and about 32" tall at the peak. So this is larger than the required 22X30 opening, right? To me, 22X30 is 'slithering'. I could then put a pull-down ladder in the garage. There's plenty of height above where I would put the pull-down. There is no mechanical equipment to worry about in either attic. I assume I would then need 5/8" drywall for the garage ceiling, as well as the common wall?

Due to the recent Code changes it may be difficult to select an attic access solution that meets the new Building and Energy Codes:

 

2009 IECC Section 402.2.3 and 2009 IRC Section N1102.2.3 and 2012 IECC Section R402.2.4 reads: "Access hatches and doors. Access doors from conditioned spaces to unconditioned spaces (e.g., attics and crawl spaces) shall be weatherstripped and insulated to a level equivalent to the insulation on the surrounding surfaces."  Energy Star Version 3 requirements conform with the 2009 IECC and 2009 IRC. The 2012 International Green Construction Code conforms to the 2012 IECC.

 

This means the attic access must now be insulated to the same level as the rest of the attic (min R-30). 

 

Her are two attic access solutions that meet these new Codes and provide solutions:

 

1.         E-Z Hatch R-42 Attic Access Door. This is a high-performance energy-efficient attic access scuttle door. It is R-42, triple-gasketed, pre-finished, and provides a 22x30” access opening. It is an energy efficient alternative to energy wasting attic pull down ladders, and exceeds all Code requirements. Deluxe version is provided with a 4-point lock and handles. Standard is $199 + ship, Deluxe is $269 + ship. The cost of this attic access door is less than the cost of a pull down ladder and an insulated cover. A step ladder can be used to provide attic access.

 

2.         Battic Door R-50 Attic Stair Cover. When pull down ladders are preferred add an energy-efficient pull down ladder cover. The kit includes stair cover box and gasket, along with a reflective shield. The installer provides the desired amount of fiberglass insulation (R-50+) into the reflective shield, and the box is placed into the reflective shield covering the insulation. The shield holds the insulation to the box. The stair cover fits between trusses. If there are no clearance issues, you can also add insulation under the shield to the sides of the box. Available in 22x54, 25x54 and 30x54 sizes.  Cost is $59.50 + ship.

www.batticdoor.com