Which Insulation is More Effective, Rolled On or Blown In?
LESLIE: Greg in Minnesota is on the line, looking for some help with insulation. What can we do for you?
GREG: Well, I’m just wondering what – which is more efficient in an attic, especially up here in west central Minnesota where we get a little cold in the wintertime. Is it more efficient to use rolled-on insulation in my attic or to use blown-in insulation in my attic?
TOM: I think that both will be equally efficient if they’re installed properly. Now, well how old is your house, Greg?
GREG: It was built in ’73 so it’s …
TOM: Alright. So it is a standard, stick-frame construction?
GREG: Yes, sir.
TOM: So, I think you can use regular batt insulation, because it’s a little bit easier to handle than the blown-in and also, after the fact, if you need to get in there to do any wiring or anything like that, it’s a lot easier when you don’t have to kind of plow through all the blown-in stuff. So I prefer batt whenever I can use it.
What I would do is I would put down 8 to 10 inches between the floor joists or the ceiling joists and I would also then put another 8 to 10 perpendicular to that. So you’re going to want, you know, somewhere in the 18-to-20-inch range of insulation when you’re done, in that part of the country.
And then lastly, make sure you have plenty of ventilation, so you need to have ridge vents and soffit vents so that you’re moving a lot of air through it. Because if not, what’ll happen is you’ll get condensation in that attic and that’ll make the insulation damp and ineffective. So good insulation and good ventilation. Put down in a couple of layers on the insulation; I think you’ll be in good shape.
LESLIE: Do you have any insulation up in your attic already?
GREG: Yeah, there’s insulation there now but it’s gotten compacted over the years. It’s blown-in insulation; it was there when we moved into the house about 11 years ago.
LESLIE: So it’s important when you’re going to put the fiberglass batts on top that you go with unfaced, right, Tom?
TOM: Yes. You always want to use unfaced insulation.
GREG: Alright. I appreciate it.
TOM: You’re welcome. Good luck with that project. Thanks so much for calling us at 1-888-MONEY-PIT.