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July 22, 2015
While most New Jersey homes don't have the recommended amount of attic insulation according to Energy Star (At least 12 inches, higher in some parts of the state), most have at least some insulation on the attic floor. When renovating their home to increase energy efficiency, most homeowners realize that adding more insulation to their attic flat will help them reduce their heating and cooling costs. However, most NJ homes are lacking insulation in an incredibly important part of the attic-- the attic access.
Not surprisingly, an uninsulated attic hatch is a terrible insulator (shocking right?). But justhow much an uninsulated hatch can counteract other insulation may surprise you.
A 10 square foot hatch in a 100sf attic can halve the effective value of the attic insulation. This means if you've installed R-38 insulation in your entire attic and forgot the hatch, the result is the same as if you insulated the attic and the hatch with just R-17!
Even attic hatches that are "insulated" can still be problem areas in the attic. If you've been around enough homes, you know that most attic hatches don't sit perfectly airtight when closed. Even most hatches that look like they close well have significant leakage around their sides if they've not been properly air sealed. Look at this picture from greenenergyaudits.com:
All those dark blue areas represent cold air leaking through the hatch in the winter time, and hot air rising out in the summer. What that translates to is money leaking out of your pocket and into thin air!
So what should you do? A properly insulated attic hatch should have a strong air seal around the outside and a thick layer of insulation over it to bring it up to close of the level of insulation in the rest of the attic. We recommend polyisocyanate (polyiso) or a similar rigid foam insulation. While slightly more expensive per square foot than fiberglass or cellulose insulation, polyiso provides a much better air seal over the attic access and doesn't allow for cracks or leaks. Air sealing works best when the entire attic plane is sealed-- leaving holes like uncapped recess lights or unsealed attic access points lessen the impact of all of the other work.
It's often a neglected part during construction and renovations, but it is just as important as the rest of your attic. Insulate your attic hatch-- it matters!