Does injection foam beat rockwool these days?

[Erikc5]

Hi, I'm new here, wanted to hear from some professional studio designers instead of insulation marketing companies on this. Searching for "injection" on here didn't get me too many hits.

Sites like https://www.allfloridainsulation.com/so ... ening.html claim their injection foam insulation has an STC rating of 53.

Another site https://www.stellrr.com/comparing-sound ... materials/ makes the foam seem equal to rockwool, but cheaper.

If I wanted to convert an existing guest house into a music studio/rehearsal space targeting ~55 STC, would you say it's possible to use injection foam and not have to tear the sheetrock open as much? Or is that just marketing tricks?

What brought me to your site is that I'm planning to buy a property with a guest house soon, but I don't have exact dimensions of the it yet so I can't really make you guys a diagram. But it's a freestanding one story structure, pier and beam foundation, wood floors, wood siding, sheetrock walls, wood studs... typical house construction for the southern USA where I'm at. The structure is probably 20 years old.

So my general plan I'm hoping would suffice to get me to that ~55 STC is taking the existing wall, adding the injection insulation, caulking the whole wall with acoustic caulk, adding a slightly thicker sheet of acoustic sheetrock glued to the existing sheet using green glue (or maybe using the channels instead, but mounted to the existing sheetrock?), and then getting window inserts for the windows or replacing them and the door outright.

All I care about is sound leaving the structure, no internal walls to consider. There will be a five piece rock band but the drum kit will be electric, not acoustic.

What do you think, am I completely overestimating how simple it is to do this without completely gutting the place and starting from the studs? Tell it to me straight, doc.

[gullfo]

the foam in and of itself will not necessarily get you 53db STC, but the construction around it along with the foam could, bearing in mind STC is only a measure of isolation down to 125Hz so bass and drum low end will not likely be as isolated as the fibrous insulation would get you. however, the injection of foam usually has better thermal properties.

you want open cell foam for this and i'd recommend thoroughly checking references since the renovation by injection without removing drywall etc can lead to damage from the expansion as well as longer times for gas-off.