Tips for Adding Floors to Attics for Added Storage

BOB: It’s a very large attic and it’s – I’ve got uncovered floor rafters. And I’ve got 35 years of stuff accumulated in that attic that I want to get rid of, alright? The problem is that the rafters are open and I want to know what to do to cover the rafters.

TOM: OK. So, first of all, if you’re – when you say “rafters,” I think you mean the floor joists. When you go up in the attic and you look down at the floor, is that what you’re talking about?

BOB: That is absolutely right, yes.

TOM: OK. So, those are the ceiling joists that are holding up your ceiling below and the floor joists if you are up in the attic and call it that, as well.

Now, you have insulation in those joists right now, correct?

BOB: That is correct.

TOM: And it’s 35 years old, so it’s – and you’ve had a lot of storage, so it’s probably sagged and compressed and perhaps pressed down. Is that fair to say?

BOB: That is also correct.

LESLIE: He’s like, “Tom, are you in my attic?”

TOM: We’re setting it up here, yeah.

Here’s what I’d do. First of all, get rid of all the storage. You know, go ahead and do that big purge. And it’s a big project. I mean I had to do this because we sprayed Icynene foam insulation in my house. And I’ve got to tell you, my attic – and I live in a family house. That attic, literally, hadn’t been emptied in generations. So, when we got that attic emptied, my first floor looked like an episode of Hoarders. We had stuff everywhere because those attics are big and they held a lot of stuff. But it was a good opportunity to purge it out and get rid of the stuff you don’t want.

But now that you’ve done that, what I would do is if you want to go back with a fiberglass insulation, I would take out the old insulation. If it’s been in there that long, it’s probably compressed and not really doing its job. And I would fill in that floor joist, all the way to the top, with unfaced fiberglass insulation. Now, even if you do that, chances are, depending on the depth of those joists, you’re probably not going to get more than 8 or 10 inches which, honestly, is not enough insulation to really do a good job in a cold area like where you live.

You really need 15 to 20 inches of insulation. So if you do a really good job with getting rid of all that storage that now you need less storage space, what I would tell you to do is to double up the insulation towards the outside walls and sort of carve out an area close to the opening where you could reserve that for insulation and put the flooring, only, there. So just put the flooring and have 8 inches or 10 inches of insulation underneath it. But then in the rest of the attic, you want to double up the insulation, putting insulation perpendicular to the floor joist and inside of the floor joist at the same time. And that would really build it up.

And I’ve got to tell you, if you spend the amount of about one month’s cold-weather heating bill on insulation, you will see a dramatic savings for every month thereafter.

BOB: Well, I think I’ve got it now to sound like an expert. Now let’s see if I can work like an expert.

TOM: Alright. Well, good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.