Bonus/"attic" spaces and soundproofing questions - AVS Forum | Home Theater Discussions And Reviews
Baselworld is only a few weeks away. Getting the latest news is easy, Click Here for info on how to join the Watchuseek.com newsletter list. Follow our team for updates featuring event coverage, new product unveilings, watch industry news & more!



Forum Jump: 
 
Thread Tools
post #1 of 6 Old 03-02-2016, 02:12 PM - Thread Starter
AVS Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 4,567
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 145 Post(s)
Liked: 172
Bonus/"attic" spaces and soundproofing questions

Brushing up a little on soundproofing concepts. I haven't had to deal with a space under the roofline before, read all the threads and articles on the subject I could find but had a few questions that weren't completely clear for me.

Most concepts are the same, DD+GG, +/- clips and channels, for walls and ceilings.

What is the preferred framing approach for the sloped part of the wall/ceiling made up by roof rafters? Specifically, should the knee wall be attached to rafters with isolation clips? Flat part of ceiling the same? Or OK to be rigidly attached since this is roof and not adjacent to any other room?

Or should I entertain the idea of a floating double rafter system akin to a double stud wall, where a non-structural set of rafters is nested between the actual structural rafters, and supported by the knee walls? These would probably have to extend to the floor, at least in some locations, even if the flat portion of the ceiling joists serves as collar ties, just to keep structurally stable. I suppose where this happens they might could ride on a footer that sits on a rubber mat to help with isolation. Has anything like that been done?

Or, a short segment of floating rafters that are suspended from the structural rafters by a relatively few isolation points?

I'm honestly not sure what effect this double rafter would have on insulating the space between rafters to satisfy code. I plan to have the structural rafters sized, if possible (I think they can be), to span the required horizontal distance without a structural knee wall or purlins (won't have load bearing wall aligned underneath). So there wouldn't be anything in the way I think of a second set of rafters. This would add load to the structural rafters though, so not sure how that effects sizing to code either.

Floor will largely be ceiling of 2 story high family room and entrance. Much of the span unsupported, I think 16" structural I flooring system will be adequate, but may investigate a few steel beams to reduce bounce. I can probably do hat/clip and DD+GG for the undersurface ceiling, and rubber mat floating floor in the theater room. Not sure I can do any better there.

Just in general, seems these roof rafters are going to short circuit a lot of effort to isolate framing. Best to just accept it, rigidly attach framing, and rely on clips and GG for isolation?

Bigus is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 03-03-2016, 01:42 PM - Thread Starter
AVS Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 4,567
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 145 Post(s)
Liked: 172
Too many words at once? lol.

I know a few have built in rooms with sloped rooflines for part of the ceiling/walls. Was hoping you guys had picked up great tips or learned valuable lessons along the way.

I think my biggest fear isn't intrusion of outside noise into the theater, but flanking noise through the rafter structure into the floor and then into the rooms below. This will be the only room of consequence on the upper (attic) level (small lobby, bathroom, and exercise room will fill out the space), so it's really just sound going down that I need to stop well.

Bigus is offline  
post #3 of 6 Old 03-08-2016, 01:47 PM - Thread Starter
AVS Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 4,567
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 145 Post(s)
Liked: 172
Thought I'd try one more bump.

Bigus is offline  
post #4 of 6 Old 03-08-2016, 02:13 PM
Member
 
jonnyphoto1's Avatar
 
Join Date: Feb 2016
Posts: 21
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked: 1
I'm also interested in this info. I'm having a new home built that will have a dedicated 20'x20' unfinished space above garage and a portion of master BR that I'm looking to eventually turn into a home theater. Not so concerned about noise bleed into garage, but since it also overlaps part of the mast BR, noise cancellation is a must in the subfloor. I'll continue to monitor with you to see if we get any good tips for 2nd floor 'bonus space' builds.


Sent from my iPad using Tapatalk
jonnyphoto1 is offline  
post #5 of 6 Old 03-08-2016, 06:40 PM - Thread Starter
AVS Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 4,567
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 145 Post(s)
Liked: 172
See guys, most important topic in the whole forum!

Hopefully someone has dealt with this. Decoupling clips/channel and DD+GG will still work, and rubber underlay with additional subfloor on top can still work.

But I have the starting room size to sacrifice some for a room within a room... if I could figure out how that framing would work.
Bigus is offline  
post #6 of 6 Old 03-28-2016, 08:06 PM
Member
 
hobsocc7's Avatar
 
Join Date: Apr 2012
Posts: 168
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 59 Post(s)
Liked: 39
I am currently finishing my walk-up attic into a home theatre. Granted I am far from actually knowing how this will work out but this is what I am doing.

Like you said clips+channel and DD with gg is my plan. My floor started with just a normal subfloor (advantac osb subfloor). I added serenity mat then two layers of 5/8 osb subfloor with green glue in-between. I am currently working on the knee walls.

My plan with advice I got was to build the knee walls on the now "decoupled floor". I could then either use clips and channel or ib3 clips to the rafters. I have chosen to do the ib3 clips in interest of saving money from more clips and channel also because I plan on putting in access to behind the knee walls.
Do you already have subflooring down? Do you have a lot of head room? Uboats might work well if you have alot of head room.


Sent from my Nexus 6P using Tapatalk
hobsocc7 is online now  
Sponsored Links
Advertisement
 
Reply Dedicated Theater Design & Construction

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off