What’s the Best Insulation for Attics?
LESLIE: Alright. Now we’ve got Charles on the line. Charles, what’s going on at your money pit?
CHARLES: We’re in North Central Louisiana and we get up in the 90s with the high humidity. But specifically, my house was built in ’91 and I’ve got good insulation in my attic: the roll-type insulation. About 8 inches of it. And we put another 3 inches of blown insulation on it.
What the problem is is I don’t have any kind of airflow to really pull the heat out of my attic. I have a big vent on the north end of the roofline and I have two turbines and that’s it. There are no, I think – what do you call them, soffit vents or something that normally you see under the edge of your roofline? On the – yeah, I don’t have any of those so I’m wondering, would that help my situation some? And if so, how do I figure how many I need and how to space them?
TOM: So, here’s how you add additional ventilation to a roof that’s configured like the one that you’ve described. The best type of insulation is, in fact, soffit venting combined with ridge venting. So soffit venting is at the overhang and ridge venting is at the peak. Now, because you don’t have soffits, there is a type of a vent called a “roof-edge vent” or a “soffit-edge vent” that essentially extends the roofline only about 2 or 3 inches and provides an intake vent for air to get in right under those shingles.
So if you were to add the roof-edge vent and then combine that with a continuous ridge vent, you would have the kind of flow that you really need. So what happens is as the wind hits the roof, it pushes up, it depressurizes that ridge, it’ll pull air out from the ridge vent while pushing air in from these soffit vents that we just talked about. And that will do a lot to cooling that attic space.
Now, those turbines that you described, if you get the ridge and the drip-edge vents installed, I would remove the turbines because they’re just going to get in the way. They’ll interrupt that airflow that we’re trying to establish the pattern for.
CHARLES: Yeah, this ridge vent you’re talking, I’m going to have to have them redo the ridge thing. It’s a shingle-type roof. Going to have to have them redo that?
TOM: Yeah, you’re going to have to do some carpentry work here. The ridge vent is pretty easy because you can cut right through the roof shingles, at the top peak, and attach the ridge vent right on top of that. And it’s a pretty watertight fit. The soffit drip-edge vent, that’s a little bit more complicated. You’d have to take apart the first couple of rows of shingles to get that in.
CHARLES: Alright. Well, I appreciate the information and I’m going to take a look at that stuff and then start looking around for a good contractor that can do that for …
TOM: OK. Good luck with that project.