# Room-in-room and acoustics



## atledreier (Mar 2, 2007)

I see alot of HT rooms being built as a 'floating' room for sound proofing. Sounds like a good idea form the point of sound leaking into the rest of the house. My question is this; How will this affect the in-room acoustics? All that bracing and stiff walls and air tight stuff. Will it be better, worse, equal? I suspect at least it may be more predictable, being closer to a simulated 'perfect' airtight room.
I ask this because I will be designing and building a new house in a year or so, and want to do as much research as possible before I start, to get the most out of the room.
I started to think about this when i got my new SVS PB12plus/2 and observed the 5mm excursion of my inner walls. :raped: I am planning on getting another plus/2, so the issue of structural damage come to mind... :hide:


----------



## bpape (Sep 14, 2006)

Room in a room is the most cost effective solution for the best isolation. DriCore flooring with walls built on top is a good flooring solution that doesn't cost you a ton of headroom.

If you decouple the tops of the walls using DC-04 clips, then you can lay new joists between the existing ones sitting on top of the wall and eliminate the need for RSIC-1 clips on the walls and ceiling for a significant cost savings. Double drywall and GreenGlue finish it off with good iso at less cost.

Yes, the extra mass does then require a bit more attention to bass absorbtion but the noise floor in the room is significantly lower for better dynamic range from the same system and power.

The things people forget to plan for is HVAC and electrical/lighting. When you cut holes for these, it pierces the sealed envelope and causes issues. Bringing things into the room in a single place (like an isolated soffit built AFTER the room is drywalled) can minimize this intrusion. Also, having things like columns in the space allows for installation of electrical in those columns (again after drywall of the shell) without cutting holes in the envelope.

HVAC is brought in inside the soffiting and routed to the appropriate places in the room again without more holes. Can lighting can be placed in the soffits with no holes.

There are a lot of other things that can be done to minimize sound transmission. We just have to plan for it accordingly.

Bryan


----------



## thewire (Jun 28, 2007)

bpape said:


> Room in a room is the most cost effective solution for the best isolation. DriCore flooring with walls built on top is a good flooring solution that doesn't cost you a ton of headroom.
> 
> If you decouple the tops of the walls using DC-04 clips, then you can lay new joists between the existing ones sitting on top of the wall and eliminate the need for RSIC-1 clips on the walls and ceiling for a significant cost savings. Double drywall and GreenGlue finish it off with good iso at less cost.
> 
> ...


In most situations you have encountered, was a fan and a larger duct or longer run between the room-in-room and the AC/heater or other rooms beneficial? Is a dedicated HVAC better as a cost effective solution to sound isolation? How do you approach this usually after the drywall?


----------



## bpape (Sep 14, 2006)

You must plan ahead for the HVAC. Normally, we bring it into and out of the room inside a soffit which is built after the room is already drywalled. The soffit is then also drywalled to provide additional isolation.

The trick is to have at least 3-4 90 degree bends in it prior to exiting the room and between there and the opening into the room. If that needs to be done outside, then an MDF boxe can be continued outside to provide the additional isolation.

In some cases, a dedicated unit is preferable and more cost effective - depends on the situation. Sometimes, you can get by with simply exchanging air between that room and another room and not even tie into the HVAC system at all. In those cases, we draw air out of the room with fans at the outer end of the ducting and leave the intake (supply) line unforced and let the pressure difference naturally draw air in. 

Bryan


----------



## thewire (Jun 28, 2007)

bpape said:


> You must plan ahead for the HVAC. Normally, we bring it into and out of the room inside a soffit which is built after the room is already drywalled. The soffit is then also drywalled to provide additional isolation.
> 
> The trick is to have at least 3-4 90 degree bends in it prior to exiting the room and between there and the opening into the room. If that needs to be done outside, then an MDF boxe can be continued outside to provide the additional isolation.
> 
> ...


That answers my question perfectly.ty


----------



## John Simpson (May 10, 2007)

bpape said:


> The trick is to have at least 3-4 90 degree bends in it prior to exiting the room and between there and the opening into the room.


That's very clever Bryan. You've helped me as well! :clap:


----------

