The second floor has been insulated for over a year now, but there was one major problem which I finally solved this weekend. The access door to the side attic was never finished, so we had a major 2 foot by 4 foot hole in the building envelope. The air handler is located in the side attic and having easy access to it is imperative so the filter can be changed on a regular basis, as well as having access for any necessary repairs or maintenance. I came up with what I think is a pretty decent solution and already there is a noticeable difference in the temperature upstairs.
Easy accessibility
The previous owner had a built-in bookshelf to cover the access to the attic. Somehow he thought that a half inch of styrofoam board glued to the back was enough insulation, but that’s beside the point. The bookshelf idea was fine, but now that we have an air handler located in that space, more convenient access is needed. And, more importantly, I want sufficient insulation so the energy efficiency and comfort are not compromised.
The removable insulated box
After considering a number of options, I came up with this solution:
Insulated box for side attic doorway.
I built a simple frame using 1 x 4 lumber to fit into the opening. I stapled on some 6 mil poly vapour barrier on the room side, and some housewrap on the side that faces the attic. Inside the frame, I used mineral wool insulation with an R-value of 13.5. The rest of the wall is insulated with R-21.5. I could have used 1 x 6 for the frame, and this would have allowed me to maintain that higher R-value, but I felt that it was more important to install weather stripping to block any drafts, an using the smaller width lumber allowed me the extra inch or so that I needed for the weather stripping. Weight was also a consideration. I wanted the box to be lightweight so that it would be easy to remove.
Weatherstripping
The weatherstripping that I used is a flexible foam that provides a superior seal. It was easy to trim with a utility knife and is screwed into place.
Not quite finished yet
The insulated box is only one piece of the puzzle. The doorway still needs to be framed and a hinged door needs to be installed. I think I will keep it relatively simple and use 3/4 inch ply (or MDF) for the door and install it with an overlay hinge, but there is no rush for that yet. My main concern was just to get the large opening plugged up. The heat coming from the side attic was like a furnace and was overwhelming any cool air from the air conditioning. The A/C should be operating at peak efficiency now.
The finished insulated box in the doorway.
The piece of 1 x 2 serves to add lateral strength to the box as well as act as handle for easy removal. It was screwed into place after the vapour barrier and house wrap were installed.
Another added bonus to this type of construction is that the insulation is visible through the poly so it will be easy to see if it should ever need to be changed.
