Old insulation ID

[Zachary Hoyt]

I have this weird old insulation in the attic of the house I bought recently, and am wondering if it's good for anything or if I should just throw it away. It seems to be semi-rigid, but not really hard. I'm planning to put down a floor in the attic and am thinking of adding 2x6s to the top sides of the existing 2x6 joists so I could put in R38 and a floor over it. These rectangular panels are not fitted together tightly so I don't think they're probably doing a lot of good, but I might be able to use them somewhere else, as I need to insulate the whole house. I'll be grateful for any insight into what this stuff is and what its R value might be.

[Mark Bolton]

Looks like mineral wool or rock wool

[Zachary Hoyt]

Thank you very much, that's helpful to know. My only experience with rockwool was in batts and was floppy. This is stiff, though it does yield some if you push on it. These panels are about 3 or 4 inches thick. Would this type of insulation be worth reusing in the walls of the house, or should I just get something new?

[Jim Becker]

With that swirly white cover, it looks like repurposed drop ceiling material that was just thicker than normal!

Beyond that, with the material all broken up like that, it's really not making for a very good insulation "blanket" as you note. If you have the space to raise the floor like you mention, yea, that would be good and you can do a very nice blown in blanket that will provide great coverage and then deck over for your unconditioned storage space. Be sure that there is proper ventilation above the conditioned space as part of the process.

[Mel Fulks]

That might a product that is for sound proofing ,not temperature

[Zachary Hoyt]

Thank you both, those are interesting points. Jim Becker, are you saying there needs to be ventilation between the insulation layer and the ceiling below, or that I need to have ventilation in the attic? If the latter I was planning on that, there is a louvered vent and I want to add a window for extra summer ventilation. If the former I didn't know about it and will have to find out.

Mel Fulks, that would make sense, and maybe I can find someone up there who would like to take it and use it for that.

[Jim Becker]

Ventilation for the attic if it's not conditioned space. That's typically at the soffits and then either at the ridge or at the gables or both, depending on the air flow needs. If you do not have that ventilation, there can be moisture and other issues. The only time space like that is not ventilated is if it's conditioned space and has a closed cell spray foam envelope including on the roof deck.

Your insulation in the ceiling should be right to the ceiling. One of the reasons I mentioned blown-in is that it readily adapts to your proposed solution to raise the color and provide more space for the insulation, including if you choose to put the add-ons perpendicular to the existing ceiling joists.

[Mel Fulks]

Lot of people use it for quieting through the wall toilet flush. It’s a big deal now with new houses.

[Jim Becker]

Lot of people use it for quieting through the wall toilet flush. It’s a big deal now with new houses.

Indeed. There are actually specialty products from the major manufacturers that are designed specifically for noise abatement applications in interior walls. It's actually a nice idea and can be actually noticeable in the sound dynamics of even a modest home.

[Zachary Hoyt]

Thanks, there's lots to think about. The roof is metal applied on furring strips over an old probably asphalt roof, so I think there may be some ventilation between the metal and the shingles, but I don't recall if there are soffit vents. I'll have to look next time I'm there.

I've not heard of the toilet flush use, it's a strange world for sure.

[Andrew Seemann]

I'm not recognizing it as a standard insulation for that purpose; it certainly doesn't suit the purpose well given the loose fit

I'd agree, some kind of product for sound abatement or something else that was intended to have a "shown" side that got repurposed for there. I'd chuck it. That kind of stuff tends to get really gross and sheddy with age. Wear a good mask; the dust that comes off it is horrific to breathe.

When you put in new insulation, you probably should pay attention to moisture control, with maybe a kraft faced insulation and putting the kraft face down or whatever is standard in your climate. We are a cold climate so the vapor barrier goes on the interior side for us. Ideally the attic should be vented to avoid ice dams. But even if it is not, putting proper insulation in will still make things much better.

[Zachary Hoyt]

I'm in a cold climate too, the house is in the northern Adirondacks. Vapor barrier on the heated side is the norm here, and the kraft face will do something, though it won't be definitive since I plan to install it from the top and leave the upstairs ceilings in place since they're in fairly good shape. I'll look into the ventilation question for sure. I wore a respirator a lot while working there this week, and will certainly wear one when I take this stuff out. The good thing is that it won't cost much to dump since it's pretty light.

[Mel Fulks]

I would think about re-using it, a bundle of a few batts is over $50. If you are not sure that it’s the sound stuff ,put a radio in a box and put
a batt on top of it and listen.

[Jim Becker]

Reuse in a pinch is fine, but it's likely best to remove that stuff and replace with a consistent and properly installed insulation layer for best performance over time.

[Zachary Hoyt]

If it's sound insulation then I wouldn't have a use for it at all. If it's thermal insulation I would not be opposed to reusing it if it would provide a reasonable R value, but I don't know how to tell.