Attic doors, covers, or hatches need to be insulated as well as the attic itself. They should have a weather strip to prevent air leakage and latches to give a positive seal. Any amount of insulation is good, but ideally, the hatch should have the same R-value as the attic insulation.
Why Insulate the Attic Door
A well-insulated attic door provides many benefits. Doing it correctly is worthwhile.
- Increased Comfort. Hot air rises and escapes through uninsulated attic doors. Cool air flows along the floor to replace it creating drafty floors.
- Lower Utility Costs. Insulating the attic can save up to 15% in heating and cooling costs. Insulating the attic door completes the job.
- Indoor Air Quality. If enough moisture gets into the attic, it can promote mold and mildew growth. Warmer moist attics increase heat and can lead to roofing damage.
Five Ways to Insulate an Attic Door
Insulating attic doors is usually a DIY-friendly project. Whether insulating an existing cover, adding a tent, or installing a kit, the time and effort are well worth the results. Hiring a contractor is an option for more complicated applications.
For effective insulating and sealing, attic doors or covers should have a minimum 12” high framed box around them that extends into the attic. If one exists or you are adding a new one, seal all the wood-on-wood connections with acoustic caulking. Boxes should be constructed of ¾” plywood–if possible.
Install a 1 x 3 around the interior of the box flush with the ceiling drywall for the cover to rest on. Use wide casing to finish the door opening. Eye hook latches can be installed to provide a positive seal.
1. Rigid Foam Board Insulation
Install rigid foam board insulation on the attic side of the attic door. Use expanded polystyrene (XPS) like Styrofoam SM. XPS is rigid and easy to cut and fit. It is R-5 per inch. Eight to ten inches thick is ideal. Two or four inch thick material requires fewer pieces.
Cut the pieces ¼” smaller than the attic cover and glue them on in a stack. Leave ⅛ “ of cover exposed on all four sides. Use foamboard adhesive. Unfortunately, the small gap is required to allow the door to open.
2. Fiberglass Batt Insulation
Cut fiberglass batts slightly smaller than the attic door to prevent the fiberglass from pulling off or being curled up when the door is closed. Two layers of R-30 batts are perfect. Glue the first layer to the door. Glue or duct tape–gently– a second layer on top.
Another option is to build a box on the attic cover. At least 12” high and ⅛” smaller than the framing. Fill the box with fiberglass batts, loose-fill fiberglass insulation, or loose-fill cellulose insulation. Spraying the outside of the box and the framing hole with dry silicone lubricant makes removing and replacing it a smoother operation.
3. Thermal Tent Covers
Premade tent-shaped attic door covers are available from home improvement outlets and online. They are a reflective insulation sandwich with a polyester filling. (Some claim an R-value of R-15. That seems to be high.)
Most of these products measure around 25” wide x 54” long and fit standard pull-down attic doors. Most come with detailed installation instructions and are fairly easy to install.
Thermal attic door covers can reflect up to 97% of the heat away from the access. They prevent air and humidity from entering the attic. Many of them are equipped with a zippered door like a tent to allow easy access into the attic without removing them.
4. Attic Door Insulation Kits
These kits are manufactured of extruded polystyrene to fit both pull-down attic doors and standard attic hatches. Available up to a standard R-38 rating and provides upgrades to R-49. They are the most expensive option but provide the best and simplest solution.
They are installed between and on top of trusses. The kits come with all the necessary hardware, adhesive, and handles.
5. Air Sealing
Regardless of the style or size of attic doors, they need to be sealed against air leaks. Warm air rises and escapes into the attic through any gap or crack. The thermal tents and insulation kits are self-sealing but the original door below them should be weatherstripped too.
The best options are compression bulb-type products that are self-adhesive. Install them on the doorstop where the attic door rests. Install four eye hooks on the underside of the door. When the door is closed the eye hooks will create a positive seal against the weatherstrip–eliminating air leaks.