How to Insulate a Ceiling Trap Door to an Attic

Attics already have that mysterious quality, where items that were at some point important to us (or the home’s previous owners) fill boxes that we forget about, and then eventually rediscover. And the fact that many attics are accessed through a trap door built into the ceiling only adds to the intrigue. (Or maybe you just have old holiday decorations up there, or left it empty, and there’s no mystery at all.)

Regardless of what’s up that ladder and behind the hatch, if the door isn’t insulated, it could be affecting the temperature in the rest of the house. In an article for ThisOld House.com, Charles Bickford walks us through the process of insulating an attic trap door. Here’s what to know.

How to insulate an attic trap door

While there’s a good chance your attic itself is insulated, Bickford says that it’s unlikely that the door is. If that’s the case in your home, he recommends two main methods:

Fibreglass insulation

This is the easiest way to insulate your attic door, according to Bickford. First, he says to cut the batts so that they overhang the backside of the attic door a bit, adding that it may take two pieces to get the job done. Then, with the fibreglass side facing down (against the door), staple it to the door. You only need one layer of fibreglass here, Bickford says, because compressing it makes it less efficient.

Rigid insulation

Making a box from rigid insulation that fits over the door’s framed opening is a more efficient and longer-term solution than fibreglass, Bickford says, but it’s also a bit more complicated.

In addition to one 4×8-foot sheet of rigid insulation, you’ll also need:

• Measuring tape

• Knife or saw to cut the insulation

• Packing or duct tape

• Caulk gun

• Construction adhesive

Because this process is a little tricker, check out Bickford’s article for more detailed instructions.