Mini Split HVAC & Soundproofing

[DrummerJoe13]

Hello,
I recently constructed a music room/studio in a detached structure on my property. There are two rooms. One is a gym room, and then there's an interior door to the music room. The music room has resilient channel and two layers of 5/8" drywall with green glue on the 3 exterior walls. The one interior wall is just two layers of 5/8" with the green glue, but NO resilient channel. I have a question about where I should place my mini-split HVAC wall unit.

I was originally going to place the unit on the back wall of the room, which would require a small hole drilled for the lines to the outside condenser unit. They claim to fill in the space with spray in insulation and cover the line on the outside. My question is, would this allow more sound to go out of the room and affect everything I tried to do to keep sound in?

The other option I was thinking about would be to mount the wall unit over the interior door in the room. The small hole would be drilled through from the other room in the building, and then the lines would run about 6-7 feet along the wall before penetrating to the outside. Would this option be better as far as soundproofing is concerned? Obviously, it would still eventually penetrate to the outside, but there would be no holes directly from the studio side to the exterior, and the line would run longer before going to the outside.

I'd prefer it on the back wall, but don't know if that would completely negate the "soundproofing" treatments that were done. I would appreciate an expert opinion on this.

Thank you!
Joe

[gullfo]

you can go with the back wall approach - two things (or maybe three): one ensure your seal on the outside and inside walls are not "hard" seals - lots of compression on soft rubber seals and hard caulk could be problematic. have in the install put a gentle bend on the pipes to ensure it's not a "tight" wall to wall connection - will reduce the potential for short circuiting that a hard connection will make. on the outside, make sure the pipes are all damped to reduce vibrations. thick, soft rubber coverings.

[DrummerJoe13]

Thank you for the reply.

So you're saying to make sure they use thick rubber to wrap the pipes on the exterior? And what exactly should they seal the hole with?

Also, would it be much better to do the other option, or would it not make much of a difference?

Sorry for all of the questions, I just want to make sure I make the best decision and don't mess up my soundproofing.

Thanks
Joe

[gullfo]

the important concept - nothing hard that connects the two mass layers and frames - obviously the floor in most residential construction will defy that, but best effort - and metal pipes, metal wires, etc tend to transfer sound - so insulating, isolating, damping all play a role in how much sound gets in or out. using soft rubber to damp plumbing is good, then making sure the connection between mass layers is as soft as possible - sometimes this is flex pipe, other times just don't screw down clamps for the pipe to both frames, or use isolation clamps (e.g. Mason Industries), and use non-hardening caulk to seal it, remember backing rod or similar soft rubber will help in retaining the caulk/sealant.

[DrummerJoe13]

Awesome. Thanks for the help!