My studio walls

C

Chadwick

New member
I was laid off and fortunately handed a nice severance package. I thought I would take advantage of some of the time and convert a small room into a studio (real fast)haha. Things aren't going real smooth. I'll give you one example. The closet accessible from the two adjoining rooms was made of half inch plywood and it takes up the whole wall. No studded wall. Not much STL there. The only way to fix this was to remove the whole closet, build a wall and then a new closet. I could go on and on. But anyway, the walls. My original intent was to go RC- 5/8 sheetrock- 1/2 sound deadening board-5/8 sheet rock. But now I'm considering cutting corners and using R/C and two sheets of drywall without the soundboard. If I do this should I use two sheets of 5/8 sheetrock or should I vary the size like maybe 1 sheet of 5/8 and one sheet of 1/2? I've read that varying the thickness improves the STL. I hate to cut corners but somethings telling me I'd better get this done and start looking for a job.
Thanks for all suggestions.
Chad
 
Chad, considering you're trying to do this fast, cheap and perfect I'd skip the third layer and spend that money finding REAL acoustic caulk. It may not be easy. US Gypsum makes a version of it, as does Owens Corning. You want all your construction to be airtight, and STAY that way - the only way that can be done is by using caulk that won't shrink away from the job.

While on the link that was put up, (Yeah, I'm the same Knightfly) check out the STC charts on John's post of Mar.2 - this will give you an idea of how much difference just a design can make. Note that the double-layer wall of STC 60 uses essentially no more materials than the two separate walls that only reach STC 40, and remember that ALL the construction assumes that you hermetically seal ALL joints. The difference is in the design, as I noted in my post of Mar.17.

Also, take the time and read or download the two US Gypsum links - there is a lot of good info there as well... Steve
 
Knightfly, you seem like the patient kind :). Think you could provide a brotha with a little advice over a pm? I sure would appreciate it. I want to start drawing up a room, but I don't want somebody to hold my hand. Just a little personal experience would come in handy before I start.
 
RichHead, I'd prefer it if we kept non-personal topics here on the board - that way, more people can benefit, comment, ridicule, etc; besides, it gets too time-consuming when I try to go mono-a-mono -

If you post a separate question, you'll probably get extra info that I might not have thought of; still another reason to keep it here. I hope this works for you - I'm not trying to be picky or anything, it's just that I'm trying to moderate two different BBS's and still finish the design for my own complex, which will (hopefully) begin construction sometime next year. Peace... Steve
 
Thanks Knightfly. I'll try to locate some of that caulk. Unfortunately one wall is already completed. I used the 50-year permanently flexible DAP brand from Home Depot. I hope that will last. So do you think I should use 5/8-5/8 or 5/8-1/2 on RC using accoustic caulk?
 
It's kind of a toss-up between two layers of 5/8 and one of each - there wouldn't be much of a mass change with only 10% more mass in that leaf of the wall, so I'd probably go with one layer of each. The difference in resonance might do as much for sound blocking as the slight extra mass, and the cost would be less.

The main thing when installing is not to overlook any details. Even one missed trick will lose you several dB of STC.

On the US Gypsum site (linked to in the previous links to John's site) most of these are mentioned, although some are easy to miss. They include using the proper screws, placing the bottom RC open side down to make fastening easier, keeping the bottom RC within 2" of the floor and the top RC within 6" of the ceiling, staggering screws between layers of wall-board, NOT using any screws thru wallboard over studs, NOT using construction adhesive to glue subsequent layers but instead letting each layer be semi-independent (just the screws) caulking EVERYTHING, taping the outer layer, running one layer horizontal and the other vertical, and probably a dozen other things I've forgotten to mention.

One thing I've not seen mentioned by anyone else, either because it's so obvious or ??? is to use masking tape or another temporary means to mark on adjacent surfaces exactly where the fastening surface of the RC is for each row, and on the other axis, exactly where the studs are - that way, when you get to the second layer, you'll know where NOT to put screws so they don't contact the studs or each other. If you use a 12" pattern per layer of wallboard, put a marker on the floor where you started so the second layer can be screwed 4" or 6" offset - keeping in mind that you still need to miss the studs...

USG also recommends that you run a heavy bead of caulk under both sides of runners (if steel) or plates (if wood), then a bead in top and bottom corners before the first layer, then fasten the second layer with about 1/4" gap from floor with spacers, then remove the spacers after attaching and run a bead of caulk in the gap.

Bottom line - if it won't float, it won't stop sound.

You didn't mention if the wall you're building has a double layer of wallboard on the completed side, but I hope so - insulation, unless you can get 2-3 lbs/cu ft density, won't make a lot of difference - that weight has been found to be the most effective for sound walls. Lighter and more bass gets through, heavier and more highs get through. For that weight, you need to find rockwool. Sometimes called mineral wool too. For that, check with commercial insulation contractors in your area. All places like Home Depot usually handle is the wimpy stuff, and some useless foam stuff.

Home Depot is reported to handle the RC-1, but a quick look last night in their drywall area turned up nada. I've not checked yet with my local Home Depot on the USG or Owens Corning Acoustic caulk - not holding too much hope though, probably a special order.

Can't think of anything else just now, hope some of this helped... Steve
 
Wow! Thats a lot of good stuff right there. I wish I contacted you about a week ago.

The one wall that I completed separates the masterbedroom from the studio. Because of the location of the door in the studio I could only fit RC-5/8-1/4. I dont even know if the 1/4 sheetrock is doing anything but it fits so I installed it. The other side of the wall is two layers of 5/8 sheetrock. The other side will also be the backside of a closet so I would imagine that will help isolate some of the sound as well.

Now heres the part that is bothering me after reading your last post. I used home depot r-13 for insulation. The other three walls have r-13 in the studs too but I havn't intalled the sheet rock over them.
The other thing is that I used 50 year home depot stuff. I can say that the rest of the details I think I covered pretty well such as making sure the wall floats, keeping screws out of the studs, location of RC etc.

Two of the walls are external walls with approx 3/4 stucco on the outside. The other incomplete wall separates my sons room. It has an existing sheet of 1/2" sheetrock and the plan is to add another layer of 5/8.

I like the idea of externally installing the outlets. My question is how would you mount them without shorting out the floating wall and so they are nice and secure since they will be vulnerable to being kicked due to not being flush to the wall?

One thing to keep in mind is that I dont have enough space to use anything more than a single door. I used a 1-3/4 inch solid particle board door and sealed it all the way around. Im not using a throught door doorknob. I'm thinking about adding a layer of something to the back of the door to thicken it up a bit. But because the door is a weak link, Im not sure if replacing all the r-13 with rockwool or externally mounting the outlets would be that beneficial.

Thanks again for all your help. It's greatly appreciated.
Chad
 
Replacing the R-13 with rockwool would help the lows, maybe 5-6 dB - it wouldn't make more than 1-2 dB difference in mids/highs.

They make hardware specifically for surface-mounting electrical - the stuff I've seen is usually either brown or white, and is about 1/2" by 3/4" for the wire mold, and the outlet boxes are shallower (less prone to kicking) than regular framing-mounted boxes. If possible, I'd mount the boxes with screws thru the sheet rock into the RC - other than super-glue, all the other ways I can think of (like molly screws or toggle bolts) would give even more penetration of the sound wall, and that's what you're trying to avoid.

The door is definitely going to be the weak link, I read somewhere last week where an experiment was done - they took a wall that tested at STC 60, installed two exterior solid core doors, one on each side, then CAULKED the doors shut - the wall still only tested at STC 44.

If you could add a layer of sheet rock on one side, maybe in such a way as to baffle the crack between door and jamb, it would help. Some drawings I saw from the BBC stressed double weatherstripping for two independent seals, one at each surface of the door.

Bottom line, unless you've got $2500 for an Overly door, it helps to be inventive... Steve
 
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