For this attic hatch you need:

2" thick foam-board (4×8 sheet) with an R-Value of 10 orgreater (you might need two sheets for larger hatches or to make it thicker)

8 -20' foamweather stripping (the wider the better)

1 can Great Stuff® foam or similar

1 tube Liquid Nail® or other construction adhesive

Misc. hardware & 2 small bungee cords to seal ittight

Getting started – depending on your region & insulationlevels you need to rip the side pieces at 11". For our friends up north thatrequire an R49 in the attic it should be ripped at 15". Make sure you leave thefactory edges for the lid to sit on. Move any insulation in the way gently outof the way & place the side pieces in place.

Attaching the pieces – The end pieces should span the sidepieces unless you are doubling up the foam. Apply Liquid Nail to where thepieces will meet & put them in place. I simply used some 16 penny nailsinserted through the side to help hold everything in place while the glue set. Oncethese panels were in place, I foamed up all the seams any cracks and theadjoining areas. Not only does this stop air leakage but also helps keep everythingin place. On top of this, simply add some self-stick foam insulation to helpensure any imperfections don't allow air-leaks.

The Lid – the lid overlaps the side assembly by about aninch which means you don't have to fidget with it trying to get it justperfect. To help hold it in place, I just used some eye hooks – 2 short ones toattach into the wood & two longer ones for the lid. I also added 2 differentsize washers (a small one that would prevent a larger 1 ½" washer from slippingpast the nut) & some nuts to attach to the lid. Then I simply used a smallbungee cord to help hold the lid down.

A few other quick notes – If you do not wish to create yourown, you might want to check out Battic Door which makes a great product withan R-Value of R50. One other option is foam board with Radiant barrier alreadyintegrated into it – if you go that route it should be facing in towards the interiorof the house for best results. To see the original article with a few more tips& links: http://blog.sls-construction.com/2011/air-se...