There’s nothing to stop that expensive climate-controlled air—heated in the winter, cooled in the summer—from escaping through the trap door. It’s like having a slow leak in your bank account.
Read This Before You Insulate Your Attic
The good news is that it’s a relatively easy fix.
Fiberglass Insulation
The easiest hedge against a thermal leak is to cover the backside of the trap door with fiberglass insulation.
Steps:
It’s also a good idea to apply adhesive-backed weatherstripping to the perimeter of the door side that closes on the framed opening. This will help keep conditioned air from leaking into the attic.
Rigid Insulation
Fiberglass will help, but a more effective long-term fix is to make a box from rigid insulation that fits over the door’s framed opening (and the folded stairs, too, if you have them). Rigid insulation is more efficient than fiberglass, and the box will be more air-tight than fiberglass, too. Win-win. You’ll want the insulation with the highest R-value (the capacity of insulation to resist the conductive flow of heat). You’ll only need one sheet to build the box.
There are three types of rigid insulation:
They’re all available in 4x8-foot sheets; if possible, buy the 2-inch-thick stock.
Expanded polystyrene (EPS) that’s rated at R-3.8 per inch of thickness Extruded polystyrene (XPS) rated at R-5 per inch Polyisocyanurate (Polyiso), rated at R-6.5 per inch
To make the box, you’ll need:
Measuring tape Knife or saw to cut the insulation Packing or duct tape Caulk gun Construction adhesive
Steps:
Attic Stair Insulation Alternatives: Foil and Attic Covers
Of course, there are also commercially available alternatives. Check your local hardware store or home center for attic stair insulation alternatives and you’ll find everything from readymade tents of reflective foil to fancy covers made from 2 3/4-inch-thick expanded polystyrene (EPS). You’ll also find pre-cut kits that you can assemble yourself. Most are available in different sizes to fit varying configurations of attic doors. And don’t sweat the money—in the end, you’ll be saving more than you spend.
