If you have a fold-down stair to your attic, you are wasting lots of heat if you haven’t insulated it. Even if you have a little hatch in a closet someplace, you should insulate that too. It’s pretty easy.
The goal is to seal the air flow between your house and the attic. This will help your living space stay warmer in the winter. Cold attic seeps into your house anyplace it can find a way. Sealing this also helps keep the house cooler in the summer, when the sun bakes your attic air well above 100 degrees.
- Weather stripping. This should be thick enough to fill the gap between the door and the door frame.
- Spray foam insulation. This is sometimes marketed as “Great Stuff,” but there are other brands.
- An insulated cover for the door opening.
Here’s a handy video.
There are variations on this kind of insulation job. You can buy the kind shown in the video (which was selling that cover!) or you can buy a different premade one made of Styrofoam. There are even more variations. The cost is usually between $100-175.
- Build a frame around the door frame.
- Seal it with spray foam.
- Cut a thick piece of rigid foam board that is bigger than the opening and lay it on top. The foam is not all that heavy, so you can toss it to one side when you use the attic opening. If you use thick board — up to 3-4 inches — that will have enough weight to stay where you put it. Or you can mount the foam board onto plywood, if you are concerned about warping.
- Caution: Do not create a plywood door on a hinge at the top of your hatch. The insulation must to be thinner along the hinge to allow the door to open, that defeats the purpose; it doesn’t insulate all that well. The second problem is that door won’t stay open unless you use hooks or weights or rope to secure it. When I go into attics with these doors, it’s awkward at best.
What do I do with the little hatch in the closet? If you have a flat hatch in a closet, you can and should insulate that. Measure the frame above the hatch in the attic. Cut a plywood board big enough to cover that opening. Glue rigid foam to the plywood. Insulate the frame of the hatch the same way people who have stair hatches do it. (video link.) Caution: use plywood, not sheet rock; sheet rock makes a mess because the edges will keep dropping dust.
Thank you, Tim B. for the question.