Jeff writes from Georgia: "OK, I've now built the pink box (Foamular 150 2-inch) to put over my attic stairs. It fits! Well, at least it covers the opening completely. Except the attic floor is not quite the same level on all four sides of the attic side of the opening. And, the four pink walls of the new box, even where level you can still see gaps. Have I built a pink elephant? Will the weather stripping around the interior attic door be sufficient? What do I need to do?"

Answer: It will be difficult to get a perfect seal in this situation. However, if the attic access has weather-stripping that is in good condition, you should still get good thermal resistance from the box you created.