John Sayers' Recording Studio Design Forum

I am building a control room for my own, commercial, use. I am not looking for perfection, but I want to do as much as I can afford. I have searched the forum and can't find a couple of answers.

I am in the country in N Central Texas, so it's pretty quiet out here most of the time anyway. I just have the occasional tractor, car with a boom box going by at 70 mph and a train about 3 miles away that I can hear on the quiet nights. The building is about 100' off the road.

This is a box in a box design.

The floor is approx 16'x13' with a sloped ceiling, 8' at one end and 10' at the other. Floors are 2x6 joists on U-boats with glass insul., stringers, 3/4" MDF subfloor and 5/8 plywood in layers. There will later be a hardwood floor. The floating floor is resting on a concrete foundation that's fairly thick, and dense (sinking anchors is rough). They used to run forklifts around in here.

What I am working with now are the walls. It is an industrial steel building with 3 1/2" of glass insul. attached to the outer walls and ceiling. The inner walls are resting on sheetblock, then the floating floor (addtional U-boats around the edges as suggested by Auralex). They are 2x4 studs on 16" centers with glass insul. The CR wall nearest the exterior is 7" from the building's exterior wall due to the steel supports for the walls.

The wiring and insul is almost complete and I'm looking at sheeting the walls. > Thanks you for all of the information posted on that in the READ THIS FIRST post. <

I would like to use wood over the studs as the bottom layer, then add 5/8" gypsum. My thinking is:

1. I want to be able to hang things (acoustic panels, pictures, shelves, etc.) anywhere without being concerned about shorting, that's why I would like to avoid resiliant channel if I can, though I'm not altogether opposed.
2. Moisture is not an issue.
3. OSB seems a little better able to hold screws for mounting said panels, pictures, etc.
4. MDF comes in 49" x 93" sheets, at least here at the local Home Depot/Lowe's. That makes it terribly difficult to haul in my 48" wide truck without putting strain on the edges of the board or having to pry it out once I get home. OSB is standard 48" wide.
5. Since the walls are on 16" centers, I will have to cut each piece of the MDF in order to make it fit the studs.
6. I am on a time limit, so I don't want to waste time any more than money.
7. From what I can gather there is about 10% density difference between MDF and OSB. I am hanging this stuff myself, that could make a difference in handling. Since I'm using 3/4" board, I'm wondering how significant that difference will be.

The bottom line is, how much difference in STC will there be to use 3/4" OSB as opposed to 3/4" MDF? If it's significant, I'll find a way to deal with it.

Also, after reading everything, I am still a little unclear about mounting the gypsum to the wood. I was thinking of using liquid nail (liberally) as well as screwing through the wood to the studs. Should I just forget the LN? Sorry, I can't afford Green Glue.

Thanks for everyone's contribution. It's been an enormous help.

Scott

Scott, I'd use the OSB in your case; you're right about screw holding power, and the slight diff in density won't make more than maybe a dB or two difference at most.

If you can't afford GG, don't use glue at all; this would bond the OSB and gypsum together, creating a single panel with only one coincidence frequency - makes the wall weaker for sound. Just use screws for the drywall, long enough to penetrate your studs by 3/4". Fill the wall with unfaced standard fiberglass, or if you can put strapping across the backs of studs in a double frame wall, and you're good... Steve

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Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...

Thank s a lot. I was a little concerned as I hadn't heard about anyone using OSB.

What about glueing the OSB to the studs? Same thing? Better to just screw it on?

Thanks again!


scott

Rod recently mentioned in my thread: ". . . you want more than 1" of penetration - I would consider 1 3/8" absolute minimum - and 1 1/2 to 1 5/8" preferable" (source). Granted, that was in the context of a ceiling and not walls...

Also, another advantage that OSB has over MDF is that OSB is more moisture tolerant. Prolonged moisture would be bad in either case, but MDF swells and even disintegrates if it even thinks about getting wet.

--Keith

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"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006

I vote for screws. Definitely.

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"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006

Maybe I should clarify the last question. Knightfly said to not use the glue between the wood and the gypsum. I plan to screw the OSB regardless. I was curious about not using glue at all between the OSB and the studs.

Thanks again.
s

Just use screws and don't use construction adhesive.

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"Converting a garage into living space requires a city permit . . . homeowners insurance won't cover a structure that's been changed without a building permit . . ." --Sacramento Bee, May 27, 2006

Screw length; agreed that for ceilings you want more penetration - for walls, 1" won't hurt either but 3/4 will be enough, since the vast majority of holding would be SHEAR, not PULL-OUT.

As to any adhesive, it doesn't hurt to use construction adhesive on first layers IF you don't ever plan on removing/saving the material, and if the surfaces of studs are a bit wavy; it's not likely with proper screw spacing, but irregular stud surfaces could possibly cause rattles with too few screws. However, you do NOT want any adhesive in between layers of the same leaf... Steve

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Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...

Thanks Steve.

I'll probably be using adhesive on the studs then, some of these are pretty questionable as far as being straight. That's one reason I wanted to use it. I've tried to use the straightest lumber I could find, but pickings weren't real good at the time. Some places I put in bracing (fire blocks) to straighten them.

As far as taking this stuff down.... it'll never be me.


I'll build another one before I rip down this one.

Thanks for all the help!
scott