Yet another studio in the home...

[stuben]

This site has been an amazing learning tool for studio design. First off, thanks to all of this forum's contributors for their time and great info. I’ve read through most of the content on this site, but I wanted to throw out some questions on yet another small studio being built in someone’s house

I just bought a raised ranch house in Jersey City, NJ. It has an upstairs living area, and a first floor area I’d like to use for music. I have three rooms to use for music downstairs and my goal is to be able to reduce sound so the neighbors won’t call the cops. The studio/rehearsal rooms are for my personal stuff; it’s definitely not planned to be a pro studio. I’ll put up with wacky studio configs (no control room window) as long as I can play with and record my bands.

I’ve attached a layout of the rooms. My first priority is to get good sound isolation in the live room so I can practice and record with acoustic drums. I’ll also have the usual instruments going (electric guitars, bass, acoustic piano, vocals). I think the diagram explains the set-up, but if you have any questions, let me know and I'll go into more detail.

Currently the concrete walls have only wood paneling against them (no drywall). The house is detached, but neighbors' houses are only about 15 feet away on both sides. Behind the house are the trains to NYC, no neighbors there, but there is some train noise that can be heard in the house.

Two concrete walls have two small basement style windows. The addition rooms (control room and foyer) are actually 6" higher than the live room. The doors in the live room shut against that 6” step. Ceilings are 6’11” tall except on the one end where there is a soffit. The floors are concrete and carpeted.

Since I have 3 concrete walls, I was going to use that as my first mass. My idea was to remove the carpet on the floor and the wood panelling against the concrete walls. Then frame three walls off the concrete with 2x4s, fill with insulation (Rockwool against the drywall, and R13 loosely in the rest of the air space), and then apply two layers of 5/8” drywall directly to the studs.

For the partition wall, on one side, I was going to remove the existing ½ drywall, add insulation, RC, and 2 layers of 5/8” drywall. I am going to leave the other side unchanged (although I’m open to suggestions).

For the ceiling, since I have so little headroom, I was going to try the idea posted on this site where you glue wallboard to the subfloor, then fill with insulation, some RC, and then a piece of 5/8” drywall.

The 2 small windows will be replaced with glass block. The 3 doors will be replaced with solid core doors and weatherstrip the seals. I’ll try to go with surface mount outlets. I also have 2 hot water radiators that I’ll need to remove, and replace once the walls are done.

Known issues:
1. Small size. The room is 6’11 high, 10’9” wide, and 18’ long. I read that small live rooms will have a bad distribution of frequencies and low end phasing. My wall work will also shave off around 5 inches all around. I'm used to recording in an apartment, so I figured this would be a step up, but from what I've been reading in F. Alton Everest's books, it's a bad move.
2. Can’t float the floor. With the low ceiling, I don’t have enough room to float the floor.
3. Ventilation/AC. Classic problem that's discussed here a lot.

Some questions I had:
1. Are my plans for the walls the best way to go? With space at a premium, are there some different techniques I could use that would give me the most space, but most sound isolation? When making tradeoffs, I'd rather have less space if it means being able to practice at midnight.

2. If my wall plans are OK, how far off the concrete wall do you frame a new wall? Is 1 inch OK?

3. Not sure if the concrete blocks have air gaps in them. They appear to be cinder blocks, and those have air cavities in them. If they do have air cavities, will that add an extra air mass to my design making a triple leaf system? Something I should be concerned about?

4. Since I don’t have much headroom in the room, I was planning to not build a floating floor. Without the floating floor, I guess I’m open to flanking noise. Is there anything I can do to improve the floor without floating it?

5. For the ceiling, I was going to follow the diagram posted on this page:
http://www.johnlsayers.com/phpBB2/viewt ... c&start=30

Is the Homosote needed? Can I replace that with the mass-loaded vinyl I see for sale at soundproofing sites to save some headroom?

6. Speaking of the mass-loaded vinyl and Homosote, would any of that be helpful for the walls? From reading the forum, Homosote can be useful with drywall to absorb different frequencies, but offers little help for isolation? Haven’t read anything positive about the mass-loaded vinyl soundproofing sites sell Just stick with the the drywall for the mass and then later apply acoustic treatment inside the room?

7. I plan to have a contractor come over and remove the radiators when I do the walls. After I’m done the walls, I’ll have them put the radiators back on. I know that the water radiators should be quiet (no air movement), but I’ll be nervous about the sound isolation since I'll need holes in the wall for the water pipes. I was planning to have a portable AC exhausting out the kitchen window. For that I’ll need to cut a hole in the partition wall. There seems to be no easy answer for the AC/heating questions, and I’m not really into running new ducts. Will my ideas for heating/AC mess up my sound isolation a lot?

Thanks so much for your time. Let me know if I can provide any other details.

Dennis

[knightfly]

Sorry for the delay, 'gators been kinda insistent lately -

your questions, sorta in order;

1 - You're on the right track for walls; if you cut down the air space, you sacrifiece TL at lower frequencies. Design for the lows, the rest pretty much take care of themselves.

2 - This depends on your isolation requirements - more space, better LF blocking. If we momentarily assume your outer wall is solid 6" concrete, placing two layers of 5/8 drywall inside with a total gap of 4" would get you around STC 78-80, with about 41 dB TL at 50 hZ - it's unlikely you'll be able to match that performance with the glass blocks (STC 44, approx.) and other windows (STC 25 if you're lucky, for 3/16" single glass) - Even if you fix your windows and your blocks have been filled with grout (solid) it's unlikely you could maintain as good performance as that wall example when you factor flanking noise into things - concrete is great for mass, but it also transmits sound really well - so any sound that gets your concrete floor moving will travel along the floor, up into the walls, and into the structure above. If the walls are all backfilled with earth, that will help damp this somewhat. My main point is, that wall example should be plenty so as not to be the weak link.

Before you get too much further, I would take a 1/2" masonry drill and drill a hole centered in one of your blocks vertically, and about 4" from a seam - this will tell you if your blocks have been filled, if not you'll hit air about 1" into the block. This can be patched with Concrete FixAll, available in several sizes at your local Homely Despot store. If the blocks are hollow, I'll have to ask a couple of buddies to help out: I'm still trying to figure out just how stiff materials have to be before the 2-leaf thing doesn't matter - if I remember correctly, it still applies even with masonry double walls, but I'm not sure what the webbing between the block faces means to all this.

3 - see above.

4 - You could help it some by using one of the "floated floor" flooring systems, that use a thin elastomer under a pergo-like stuff - takes about 1/2" total headroom and helps a small amount, but nowhere near what a true, high mass floated floor can do.

5 - That was a borrowed pic, which is why I mentioned in the text above it to forget the celotex - same with the MLV, unless your wallet is ALSO mass loaded... simplest and best way to do the bottom part of that ceiling is just use RC and two layers of 5/8, after stuffing the cavities with fiberglass. Follow all recommendations on the "complere section" sticky for offsetting joints, marking positions of everything so you don't miss with any screws, use real acoustic rated caulk, etc - The RC uses about 1/2", and the total with two layers of 5/8 rock comes to a headroom loss of 1-3/4" for that ceiling.

6 - Just stick with double 5/8 rock and build tight - to beat this, you'll need to spend about $2000 on specialty stuff and only gain a dB or two. Definitely NOT worth the effort IMO.

7 - I've not done much of anything with hot water heat, but I'd ask your contractor if they have any kind of isolators available that will cut down sound traveling along the pipes - being hot water or steam, it will need to be specific to that job. I'm thinking along the lines of some type of corrugated expansion joint. This will need to be addressed before you finish your walls, as it might need to go inside the wall. Other than that, caulking thoroughly and NOT mounting pipes rigid to framing... As far as how much you'll lose by heat/AC, it's difficult to guess - I'd say probably not as much as leaving a single door in the partition wall. Your kitchen looks pretty much like a seive for sound, what with the windows, AC unit, etc - so you'd need to stop the sound at the partition wall.

If there's room, I'd consider a full double frame wall (No RC needed) with two doors and good seals. Even if you break the wall with vents, if they're done with enough bends and length, and lined with rigid fiberglass duct board you should still get enough isolation by the time the sound escapes the house.

For HVAC ideas, check the sticky on HVAC started by Mangled - if you break the partition wall but build a couple of baffled silencer boxes(one for in, one for out) you could minimise the loss in performance of that wall.

It's after 3 am here, so gotta give up for now - hope that got some questions out of the way... Steve

[stuben]

Thanks for the advice. This week I'll head to Home Depot and get some concrete patch and then try drilling in the wall to see if the concrete blocks are hollow or not. I'll respond back with my results. Thanks, Dennis

[stuben]

I drilled into the concrete wall as you suggested and it looks solid. I went in about 2 inches and no air gap. So I think I should be OK with building new walls off of the concrete wall and not having to worry about creating a triple leaf wall.

When you refer to the Pergo-like floated floor systems, is that just the laminate flooring systems you can buy at Home Depot or is there a special version for acoustic uses?

Thanks,

Dennis

[tsanchez37]

Okay, so what if the cinder blocks *were* hollow?

What would change? I have a hollow cinder block basement and I am trying to get my head around this problem...does it qualify as a "double leaf" or not? I've read all over this, and other sites, but I cannot find an answer.

Do I need to put another wall on the inside of the cinder block one? If I do, will it gank things up? I would hate to do all that work only to find out I had to tear it all out.

I have a post over in the "design forum" right now (another noob...) if you want/need to get a look at some initial design ideas I'm kicking around.

Thanks for any help!

Tim

[knightfly]

It's 4 AM right now so I'm needing to drag off to bed; here's a (hopefully) helpful link on block walls, may be a while before I get more time -

http://irc.nrc-cnrc.gc.ca/practice/noi1_E.html

Something to study at least... Steve

[tsanchez37]

So from this doc, I gather that if I have no way to tear down the wall and rebuild it, I can achieve decent STC by adding drywall

Improving Single-Leaf Block Walls

Figure 3 shows that using heavier block to get a greater STC rating leads to walls that are impractically heavy except in special circumstances; the maximum STC in the figure is 56 for a block weight of 36 kg (nom. 80 lb). Adding materials, such as sand or grout to the cores of the blocks, makes them perform like solid blocks; the increase in transmission loss due to the increase in weight can be estimated from Figure 3. Adding sound-absorbing materials is usually not very effective because the transmission is primarily through the structure of the block. Two-leaf masonry walls can also be used in critical applications, but require especially careful installation. It will be shown that high STC ratings are more easily obtained by adding layers of drywall mounted on studs or furring.

So it looks like my best bet is to simply add a couple layers of drywall to the basement walls - Unless I'm reading it wrong...

[knightfly]

Think of the wythes in the blocks as wall studs, and the flat parallel masonry as wallboard - voila; mass-air-mass system...

So yes, your best bet would be to add a couple layers of drywall against the inside of the blocks - no air gap, make sure the blocks are sealed and there is no moisture problem to overcome on the wall, get some liquid nailz adhesive and go for it. Follow the "spacers and acoustic caulk" recommendations for typical sound walls in the stickies section - IOW, leave 1/4" gaps around perimeters of the wall(s) and seal with acoustic caulk... Steve

[tsanchez37]

Thanks so much!

I'm sure I'll be back with more questions in the near future.

Tim