Frost

When I walked outside this morning, I noticed the roofs of the houses all around mine had heavy layers of frost on them. But not mine. That surprised me, since I just had a vast quantity of insulation installed in my attic. I assumed the insulation would prevent the heat from inside the house from entering the attic...and I assumed the warmth of my attic was responsible for the lack of frost on the roof.

In fact, when the insulation guy came to give me an estimate a few weeks ago, he pointed out the same thing to me. My neighbors' roofs were all coated with frost, but mine wasn't. He explained that was because the warmth of my attic either melted the frost or didn't allow it to form. Once the insulation is installed, he said, my roof would look just as frosty as my neighbors' roofs. He was wrong.

I am sure my attic needed a LOT more insulation. I am not sure, though, why my roof does not have frost on it. Is my assumption about the warm attic right? If so, where is the warmth coming from?

You probably don't know. You probably don't care. That's alright. I'm asking anyway.