Can Rockwool Insulation be compressed or squished to fit through a 4'' hole and then rexpanded?

Question

I just put in recessed lighting and lost a lot of soundproofing in the room. There is some insulation in the ceiling, but since cutting the holes in the drywall, sound is leaking out like crazy (understandably). The lights are LED and rated to be up against insulation, but I know rockwool is really good at sound dampening. I wondered if I could pull down the LED lights, and then stuff rockwool up above to reduce sound leaking through the light holes. I know it's not like fiberglass, so is it possible to stuff in there?

Thanks!

Answer 1

Yes, rockwool will expand after compression. I have often squeezed it into cavities through openings, and found it restores to the original size. Once pushed through it expands and you can reach in to guide it into its place.

Rockwool is quite "brittle", much more so than fibreglass, so cutting and deforming may cause it to fluff apart (if that's what we could call it). Cut it into appropriately sized pieces/strips with a sharp utility knife, to make the piece compressible and to help with placement.

What may help is if you place the compressed rockwool in a plastic bag to reach it through the hole. That will make it easier to slide in. Then remove the bag in the cavity and repeat for the next piece.

Alternatively you could use a short piece of 4in tube: squeeze piece into tube, pass one end of tube through hole, retract tube while at the same time pushing rockwool through the tube.