One recent renovation project house was built the same year as the U.S. oil crisis, so you would think the attic insulation would be nice and beefy, right?

Guess again.

Turns out, the ceiling insulation only met ‘minimum code’ standard back in 1973 and hadn’t been upgraded since.

In North Carolina, high efficiency residential ceiling insulation should be R-38. Given the settling and moisture content of the loose-fill fiberglass, I estimate this home’s ceiling was only insulated to a factor of about R-17.5.

And that’s not even the worse news….

The really bad news was that neither the attached garage nor porch ceilings had a single bit of insulation!

Now keep in mind this is one continuous attic space. So for 39 years, these unsuspecting homeowners had a thermal hole greater than the size of a car in their roof!

All told, the uninsulated portion consumed over 25% of the total home area. And sadly, this is a very common situation.

How could this happen?

The minimum building code requires insulation for heated and cooled space, not for unconditioned space.  So literally, the conventionally installed insulation was placed only above the conditioned rooms, despite the fact that both conditioned and unconditioned rooms share the same attic.

This of course makes no thermal sense. Unchecked solar heat radiates inside the attic, while precious air conditioning and heat from below, continually streams to the outside.

In green building, this entire attic is treated as a single unit and will be 100% insulated, regardless of the room type below. High performance homes have continuous and tight thermal envelopes.

A well insulated home is one of the most cost-effective ways to save energy and reduce heating and cooling bills. Plus, the thermal resistance and sound dampening is greatly improved in your home.

Turns out the uninsulated portions were a blessing in disguise. The new home owner opted to foam insulate the roof deck, which allows us to totally remove the yucky fiberglass all together!

I wonder – when was the last time you checked your ceiling insulation?  Does it only meet ‘minimum standard’ too?   If so, I strongly urge you to beef it up before the cooling or heating season.

In a conventionally built home, 40 percent of your cooling and heating typically escapes out of your roof.

If you’re curious to know what your r-value per inch of existing insulation is, please see the insulation table in my Sneaky Solar Strategy video.

You can share your insulation findings here.

{ 2 comments… read them below or add one }

Phoenix Windows July 31, 2012 at 5:18 pm

The attic is often an overlooked and forgotten space, yet it can be an energy drain or shield in a home. The other huge contributing factor to maximizing efficiency in a house is to have dual pane windows installed. The initial cost will make up for the savings in the long run.

Home Michael Buble May 4, 2014 at 10:17 am

Having read this I thought it was really informative.
I appreciate you taking the time and energy to put this content
together. I once again find myself personally spending way too much time both reading
and posting comments. But so what, it was still worth it!

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