When it comes to insulating your home, it seems like there are endless ways to make small improvements to the temperature-retention ability of our homes. But there is one item that is often overlooked…. Just what are you supposed to do to insulate over the pull-down attic staircase? It is drafty and cold underneath the opening in the winter, and the heat pours in from the attic in the summer. Loose batts of insulation are hard to get to stay in place while you fold the ladder up, and even with insulation, there is still a draft around the door.
Copied from thermadome.com
There are numerous articles online about how to construct an insulating box to fit over the unit. If you are at all handy, and have the tools required, and don’t mind dealing with the mess (cutting rigid foam is messy!), then you may want to try to make your own. However, I would suggest that you consider a product that I have installed several times, the Therma-Dome. There is some assembly required, but the foam board is all cut to size to fit over the attic staircase, and all of the materials that you need for the project (even foil tape and glue) are included in the box. The only tools required are things that most homeowners have easily available: a hammer, scissors (or a knife), and a caulking gun.
Picture copied from thermadome.com
The Therma-Dome is more than just insulation – it also has a nice foam-core vinyl compression gasket (similar to the gasket that you see on exterior door weatherstripping kits) that blocks any draft between the attic and your living space. The compression tension is maintained on the gasket by using Velcro straps on each of the short ends. They attach to the frame of the ladder using large staples (included with the kit – this is all that you need the hammer for). This technique is more effective than any other type of attic staircase gasket/weatherstripping methods that I have come across in any how-to articles. The Velcro also keeps the dome in place – you may not realize it, but if your home has good air sealing, and all of the windows are closed when you close the front door suddenly – that “burst” of air movement caused by the front door could knock an unstrapped attic stair cover out of place, allowing the drafts through and decreasing its overall effectiveness.
The dome also lifts off of the attic staircase as a unit – many of the designs I have seen (both DIY project ideas and finished solutions available for sale) have a “lid” that removes for attic access, but the four “sides” stay in place. To me, that design seems too susceptible to damage: You’d have to step up and over the side of the box to get in and out of the attic, and passing anything up and down the stairs for storage requires an extra lift instead of just a “slide it over the edge” technique. There is also the safety issue of having to step over the side of the box to get on or off the top of the ladder.
I am able to assemble a dome kit and have it in place in about 15 minutes (as claimed on the manufacturer’s website). However, I am a handyman by trade, so I think that the average homeowner may take just a little bit longer. The assembly instructions are detailed and clear, and the actual assembly didn’t seem to me to be any more complicated than the average bookshelf assembly. (in fact, it seemed a lot easier!)
That 15 minutes of installation is supposing that there is decking in the attic. If there is no attic decking, you will have to allow some time to cut some strips of plywood or OSB to lay around the opening (1×6 or 1×8 board could also be used, although it seems like OSB is easier for me to come by in my “materials pile” left over from other projects). This will give the gasket on the dome an even surface to seal against. While you are installing the dome (whether you have to install any decking or not), you may want to have a can of spray foam handy to close any gaps around the attic ladder door frame, decking, or any construction voids that are under the “dome” that air may penetrate. The tighter the seal, the better the insulation factor will be. The “dead space” between the ladder door and the dome actually serves as additional insulation.
One tip that I learned from experience the first time I built one of these (and yes, it was one of the first things written on the instructions sheet, if I had been paying attention): make sure that you assemble the dome in the attic, unless you are absolutely sure that you have clearance to put it up through the attic access door once assembled! If you have low overhead clearance in the attic (such as in a ranch home), you may find yourself having a tough time getting the finished product through the attic door!
Therma-Domes can be found by searching different internet shopping sites. I just searched and found results on Google, Amazon and Bing, with prices ranging from $120 – $170. Just be careful about shipping charges, those will probably add up real fast; although it is light, it comes in a big box, which requires special handling by the carrier.