First post!!

So, as usual, I'm in the planning stages of my first HT, in my basement. I've read alot and think I have a decent plan for noise isolation, I hope!

BUT, one question is how to isolate perpendicular walls coming off of the HT. My HT won't share any parallel walls with any other room, other than a storage room, but it has 3 wall running perpendicular. Two to form a hall leading to the HT door, and a 3rd to form the storage room that sits parallel with the hall. On the other side of the hall/storage is a rec room.

I am planning on building the walls of the HT with 2x4 framing and 5/8" DD and GG. I've been thinking of leaving a 2" gap from the perp wall framing to the HT framing, then butting the drywall up to form the corners and sealing with acoustical caulk before taping and mudding. Maybe stuff some fiberglass in the 2" gap??

Anyone dealt with this before? What's best??

Thanks!

A diagram would help us understand your needs but maybe staggered studs for that wall. A 2 inch gap seems pretty drastic. I would think a 1/2 inch would be sufficient.

I have a perpendicular wall coming off one of my HT walls, which will enclose a utility room and my eqpt rack/opening. I framed this wall traditionally with the exception of leaving around a .5-1" gap between the last stud of the perp wall and the tie in stud(s) of the HT wall. Fastened the perp wall at upper joist and floor and plan to use one DC-4 RSIC clip to fasten and provide stiffening of perp wall to HT wall about 1/2 way up.

Someone else might have a better idea but this is the best approach I could think of. BTW...my approach was to address concern over the HT wall transmitting flanking to the perp wall via DIRECT contact. Thought it was easier to just decouple the two.

http://www.soundproofingcompany.com/library/articles/room_within_a_room

This may help

Generally the perpendicular wall is attached to the outer wall in a double wall configuration.

http://www.soundproofingcompany.com/library/articles/room_within_a_room

This may help

Generally the perpendicular wall is attached to the outer wall in a double wall configuration.

Ted,
Are you saying that the HT wall should be of double wall construction and then just connect the perp wall to the outer section of the double wall? If so that makes sense, but what if the HT wall is just single wall construction...will the original method I suggested be OK for decoupling?

http://i625.photobucket.com/albums/tt333/feotto/perpwall.jpg

Good info guys. Here is a shot of my plan so far...

http://img10.imageshack.us/img10/5533/htview1.png

I also wonder about the double wall comment. I'm not planning on using a double wall because the theater is only joined to a hall and a storage room. The rest will be open to the rest of the basement.

Fotto, I hadn't thought about a RSIC clip to fasten the perp wall to the HT wall. Maybe I hadn't thought this through, but didn't plan on joining them in any way other than with the drywall joints.

In addition to providing some support along that wall intersection, I'm guessing that not having ANY connection would be something that the building inspector would frown on, but not entirely sure. For the cost of a clip or two, it's buying me some peace of mind.

If you're concerned about sound conducting along the perpendicular intersected wall, I would have assumed typical decoupling of the theater framing would be in place.

If no decoupling, there will be no high isolation, so the method of perpendicular wall attachment wouldn't matter at all.

OP: I have to wonder if going through all the effort is worth it in your case. Your hallway does share a doorway with the HT space, and that will be the weakest point in your isolation by far. Yes attaching the perp walls will create a flanking path, but have you considered the ceiling yet...?

If you're not planning on isolation via de-coupling with your HT ceiling, all of your perp wall efforts may be moot.

If you are going to put the effort forth to decouple your ceiling. IMO you might as well build a double wall for the hallway/storage room. At least at that point, you know you've covered your bases.

fotto: I'm not a building inspector, but I have to wonder if they will care about the use of a clip to structurally attach walls together. I've seen countless division only type walls, that don't attach to another perpendicular wall to form a room. Their only structural connections are at the top sil and the bottom plate.

One follow-up question that may further help OP and myself out....

In my case, I have one 22' side HT wall that's running under a wood beam with single stud 2x6 construction, which I decoupled via DC-04's to the beam. If I were to add staggered stud 2x4's 24" OC to that wall (on HT side of wall) for proper decoupling to adjacent rooms....would you suggest I still keep the DC-04's for additional decoupling from the top plate to the beam?

Like OP, I also have my HT entry door in this particular wall.

Excellent question.

You would still keep the DC-04s. You would have a decoupled wall (both sets of studs move independent of the other = decoupled from one another) and you would have also decoupled the 2x6 frame from that beam. Beams and stairwells are bad for us, being that they are such excellent conductors

If you're not planning on isolation via de-coupling with your HT ceiling, all of your perp wall efforts may be moot.

If you are going to put the effort forth to decouple your ceiling. IMO you might as well build a double wall for the hallway/storage room. At least at that point, you know you've covered your bases.

I'm certainly going to isolate the ceiling, other walls, etc. This question was just related to one part of the theater.

In effect, I'm looking at the storage room as my double wall, with a 7' air space between the two walls. The other side of the storage room is a rec room, so I care about the sound penetrating there, but don't care if it's noisy in the storage room. Maybe this is where my situation differs from the norm. If I cared about the noise in the storage room, then a double wall would be best, then the perp wall would be attached directly onto the outer double wall. But since I don't care about the storage room, not sure of the tactic.

But I don't want flanking noise in the rec room directly through the perp walls, which relates to my original question. Fotto and I seem to have the same problem and similar ideas to fix it. Maybe this means it would work???

If you want to isolate sound, create your sound perimeter at the 4 walls and ceiling of the theater.

Your existing plan (as I understand it) will allow sound to leak everywhere, including that stairwell.

OK, maybe I should describe the rest of my plan. Thought I would focus on this one aspect that I don't really know how to handle, but maybe that doesn't work so well.

The left wall of the HT will be up against a basement concrete wall. I will use a single 2x4 wall with 24" OC that is spaced 2" away from the concrete. Fill with R19. The top of this wall will be isolated from the joists above by a floating ceiling (if I can) or RSIC clips. I'll use 5/8" drywall, GG, 5/8" drywall, screwed directly to studs.

The front and back wall are open to empty basement. Again, the same single 2x4 wall with 5/8", GG, 5/8". This time R13 fiberglass.

The right side wall, in question, will have the same framing, drywall, and GG, R13 fiberglass, but then not sure how to isolate the perp walls.

All drywall will have acoustic sealant between joists and openings, then taped and mudded. Door will be solid core with some kind of decent sealing (haven't detailed this out yet). HVAC ducts will be insulated flex tube with hopefully some bends.

Questions:
- Issues, suggestions? Is this a noise disaster waiting to happen?
- How do I isolate the perpendicular walls? (and especially the wall that forms the back wall and one hall - no double wall could be between)

bob350....Just my 2 cents here but I suspect you will be further advised as follows:

Left wall: Since it's against the block wall and you will decouple top plate to joists you're good to go.

Front/back walls: You have standard 2x4 stud construction but no good decoupling for flanking (similar to me execpt I used DC-04 from top plate to joists). Best choice is to do staggered stud construction or use RSIC/hat channel between studs and drywall. I would personally still use DC-04's at top plate to joists as well in either case.

Right wall with perps: If you do staggered stud, or double wall, or RISC/hat channel, then the perp wall would most likely be "decoupled" even if you directly attach it to HT wall given that the HT wall is correctly decoupled.

I have two walls against my foundation block and two that are exposed to adjoining rooms. After further thought I plan to add staggered stud to those two and will keep DC-04 clips on both from top plate to joists.

I'm saving my 20 min consult call with Ted to address what drywall configuration/GG combo I'll need based on that construction.;)

The left wall of the HT will be up against a basement concrete wall. I will use a single 2x4 wall with 24" OC that is spaced 2" away from the concrete. Fill with R19. The top of this wall will be isolated from the joists above by a floating ceiling (if I can) or RSIC clips. I'll use 5/8" drywall, GG, 5/8" drywall, screwed directly to studs.

Sounds good. The stud wall can be 16" OC. No advantage to 24" OC in a decoupled wall. Also use R13, not R19

The front and back wall are open to empty basement. Again, the same single 2x4 wall with 5/8", GG, 5/8". This time R13 fiberglass. Secure to joist with DC-04 clips.

These walls would need to be decoupled as well. Staggered stud or double stud (better). Secure to joist with DC-04 clips

The right side wall, in question, will have the same framing, drywall, and GG, R13 fiberglass, but then not sure how to isolate the perp walls.

That wall will need to be decoupled as well, just as mentioned for the other walls.




The ceiling would be decoupled from the joists with an array of resilient clips.

This would give you 4 decoupled walls and a decoupled ceiling. You are building an aquarium, and can't have Saran Wrap as one of the sides

bob350....Just my 2 cents here but I suspect you will be further advised as follows:

Left wall: Since it's against the block wall and you will decouple top plate to joists you're good to go.

Front/back walls: You have standard 2x4 stud construction but no good decoupling for flanking (similar to me execpt I used DC-04 from top plate to joists). Best choice is to do staggered stud construction or use RSIC/hat channel between studs and drywall. I would personally still use DC-04's at top plate to joists as well in either case.

Right wall with perps: If you do staggered stud, or double wall, or RISC/hat channel, then the perp wall would most likely be "decoupled" even if you directly attach it to HT wall given that the HT wall is correctly decoupled.

I have two walls against my foundation block and two that are exposed to adjoining rooms. After further thought I plan to add staggered stud to those two and will keep DC-04 clips on both from top plate to joists.

I'm saving my 20 min consult call with Ted to address what drywall configuration/GG combo I'll need based on that construction.;)

:)

Right wall with perps: If you do staggered stud, or double wall, or RISC/hat channel, then the perp wall would most likely be "decoupled" even if you directly attach it to HT wall given that the HT wall is correctly decoupled.

Ted....: You replied to the above with a simley, so hopefully you can clear up my confusing as to what fotto is expecting.

If I understand the definition properly. The only example that fotto gave of a truely decouple wall is the double wall construction. ...and that, only if the top of the interior wall is fastened to a floating ceiling or existing joist with clips. Correct...?

A staggered stud or RISC/hat channel wall will still have a direct flanking path to the prep wall. Sure it will be far better than a single stud wall, but not truly decoupled.

OP: If a floating ceiling is in your future. I think you owe it to yourself to spend the small additional amount and do double wall construction down the right side of the HT. I understand why isolation isn't a concern in regards to the storage room, but including it make everything so much easier.

With that said..., I'd do whatever Ted suggests.

Good Luck with the build.

Smoke,

Fotto has examples of all 4 walls being decoupled.

A staggered wall
A double stud wall
A single stud wall with resilient (drywall) clips

All examples of decoupled framing. All would benefit from themselves being disconnected from the joists overhead.

Let's define "decoupling." A partition is said to be decoupled if the outer leaves can move independently. A staggered stud wall has drywall (1 leaf) on one side and drywall on the other side (the second leaf). The studs that hold each drywall side are different. "Blue studs" hold 1 side of drywall, and "Red studs" hold the other side of drywall.

So if you push on one side of the wall, there is no corresponding movement on the other side. The wall is decoupled.

Then we'd like to reduce the contact of that wall framing from the joists. This act isn't really called "decoupling" though that's what everyone says. You could connect a single stud wall to the joists with these clips and the single stud wall is still a coupled wall.

Lastly, to clarify, there are clips that decouple drywall from the studs or joists. There are typically PAC RSIC-1, WhisperClips, or Isomax clips. There are also the different DC-04 clips that disconnect the stud wall from the joists.

Make sense?

Thanks all for the advice! It might be sinking in...

I've been thinking that if a wall of the HT doesn't directly touch another room, then the open air space to basement would dissipate the noise. But if I understand correctly, this will just transfer the noise to everything else boxing in that open basement area, namely the floor above, room 7' over, other concrete walls, etc. So to prevent that, you need a double wall (at best) or some other technique to prevent the sound from escaping (more than my double drywall, GG, and R13).

Also, I'm planning R19 on the left side (concrete wall) mainly for the insulation aspect. I'm a little worried that R13 on the concrete won't keep the cold out enough in the winter. But it's a below ground wall, so not really sure if this will be a big problem (??). But I do know that I don't want my wife to get cold!!

The stud wall can be 16" OC. No advantage to 24" OC in a decoupled wall.

I thought I saw somewhere that 24" OC was better for sound. Maybe this was pertaining to a non decoupled wall?

I was also thinking that the framing / wiring would be a little quicker, but maybe this is splitting hairs. Is 24" OC worse?

Hey Bob,

Thanks for being so patient. You got it.

If that wall were above ground, the temperature differential would warrant R19. Below grade the differential is much less. R13 will be fine, and we don't worry about compresing the R19 and causing it to conduct vibration.

Please continue with any questions.

I thought I saw somewhere that 24" OC was better for sound. Maybe this was pertaining to a non decoupled wall?

You got it! Not an issue once decoupled.

I was also thinking that the framing / wiring would be a little quicker, but maybe this is splitting hairs. Is 24" OC worse?


24" OC meets code and is just as good. Personal preference.

Thanks Ted.... I think I was stuck on the concept of a truly decoupled wall needing to have no flanking paths.

In my mind, a staggered stud wall would share a top sil and a bottom plate (flanking path), and single stud wall using clips still shares the same studs, sil, and bottom plate, (flanking path).

Thanks for clarifying.

Hey Bob,

Thanks for being so patient. You got it.

If that wall were above ground, the temperature differential would warrant R19. Below grade the differential is much less. R13 will be fine, and we don't worry about compresing the R19 and causing it to conduct vibration.

Please continue with any questions.

Thanks! You've been a great help!

Regarding R13/R19, I was planning on using the 2" gap from the single 2x4 wall to the concrete to allow R19. Do I still need that 2" gap for sound if I use R13?

Regarding R13/R19, I was planning on using the 2" gap from the single 2x4 wall to the concrete to allow R19. Do I still need that 2" gap for sound if I use R13?

In general, a larger air cavity will isolate low frequencies better. So more = better.

Leave the 2" and use the R13

After all of this, I'd take smokinghot's suggestion of "do what Ted suggests".....Ted's the boss, we're just helping to "man the phones":)