John Sayers' Recording Studio Design Forum Archive

I think it's the 5/8" drywall that made it firecode. It is (or was) throughout the garage, walls and ceilings alike.

• My original west wall had 5/8" drywall over 3.5" of fiberglass insulation with kraft paper. I removed the drywall and the insulation and cleated in some 15/32" OSB. I will beef up this wall between the studs.
• My original south wall had 5/8" drywall over 3/8" OSB over 3.5" of fiberglass insulation. I removed the drywall only. The OSB is now exposed. I will beef up this wall over the OSB after the concrete work is done.
• My original east wall had 5/8" drywall only. There is 3/8" OSB on the outside of the studs for a short distance heading south. I removed the drywall and cleated in some 15/32" OSB. I will beef up this wall between the studs.

sharward wrote:The only thing I did differently this time was to pre-drill the holes in the cleats. I split so many cleats on the other side.

Yikes! I just realized the error of my ways! If I attach my final layer of 5/8 to cleats that are split due to my carelessness, then in theory, the final layer could fall off if the cleats were to break in half!

Perhaps I need to replace the cleats that are split, eh?

Got your PM, and good thing; you are heading for trouble with your screw plans. You need to keep in mind that

ALL screws need to be into STUDS, not just the OSB, and that

With that many layers, it's important to have DEEP penetration, especially for the subsequent layers.

I would NOT use any screw that gives less than 3/4" penetration into the STUDS for the weight of wall you're building. Because you're building separate frames and insulating well, you don't need to worry about the minor flanking that can happen with screws when using single frames and no RC.

Speaking of studs, what's your spacing for the inner 2x6 frame? If not 24", it SHOULD be - see this for a reminder

http://forum.studiotips.com/viewtopic.p ... 280e1d399c

You'll need a few rolls of masking tape and a few "sharpie" markers, but you WILL need to completely map your screw schedule to avoid collisions from layer to layer. No doubt your "seismic consciousness" will want a full schedule for each layer, which means you need to divide the screw spacing by the number of layers and build a "map" for each layer. This will be almost "surgical" for edges, since schedule calls for 8" spacing at edges PER LAYER. The 12" spacing in the panel's field won't put your fasteners quite so close together, but it's still easy to goof.

Simplest way to get this right is to snap chalk lines across each layer in both axes, so you just drive the correct length screws at each intersection.

Another biggie - is your old concrete GONE, and the new floor finished? If not, why are you doing drywall? Murphy's law WILL get you on this - if there is ANY way to destroy your new drywall with ANYTHING HEAVY (like chunks of concrete, jackhammers, pry bars slipping, etc, it WILL HAPPEN.

The less NEW construction you have in close proximity to any DEMO work, the better.

Gotta go weld the muffler back together on my backhoe (pays to watch overhead, especially after dropping a fairly heavy load INSIDE a building and then backing out ) and then build a 10x12 sliding door - after which it's time to move everything out of my cramped garage, move everything OUT of my OLD studio and INTO the garage, DEMO the OLD studio, build some more trusses in place, remove 2 more 6x6 poles, pour the remainder of the shop slab (12x48), re-frame/re-side 72 feet of 12' tall wall, dig 200 feet of ditch, lay conduit, re-route and re-wire electric service for dual 200-amp services (house and shop), etc....

(but today I'll settle for the muffler and a working door) STeve

knightfly wrote:Got your PM, and good thing; you are heading for trouble with your screw plans. You need to keep in mind that

ALL screws need to be into STUDS, not just the OSB, and that

With that many layers, it's important to have DEEP penetration, especially for the subsequent layers.

I would NOT use any screw that gives less than 3/4" penetration into the STUDS for the weight of wall you're building. Because you're building separate frames and insulating well, you don't need to worry about the minor flanking that can happen with screws when using single frames and no RC.

Hold on a minute. You realize we're only talking about outer leaf beef-up strips, right?



I don't want to freak out until I'm sure we're on the same page. And then expect a big-time major freak out!

Speaking of studs, what's your spacing for the inner 2x6 frame? If not 24", it SHOULD be - see this for a reminder

http://forum.studiotips.com/viewtopic.p ... 280e1d399c

Uh, no, I'm planning 16" o.c., as has been on every framing plan I have ever posted on this thread! Including this one that I posted on August 22:

Another biggie - is your old concrete GONE, and the new floor finished? If not, why are you doing drywall? Murphy's law WILL get you on this - if there is ANY way to destroy your new drywall with ANYTHING HEAVY (like chunks of concrete, jackhammers, pry bars slipping, etc, it WILL HAPPEN.

(sigh) No, the concrete is not gone yet. I was planning on doing it after my side east and west outer leaf walls were beefed up so that my concrete would stay cleaner. I may go with a decorative covering -- that's why. Not something that I put a lot of thought into though. I didn't think the order of these particular operations mattered much.

Please clarify what I'm supposed to do about my beef-up, Steve, and soon -- I'm really starting to freak out here!!

Bummer that my 1,000th post has to be so negative and upsetting...

Keith,

I can't believe you have made 1000 posts and have only just started!!

What have you been doing?? - that's some serious planning my freind!!.

I can't see that 16oc or 24oc will make one iota of difference in walls like yours. Those things will stop a missile attack. whats 1-2db between freinds anyway.

I hope you don't take/this that the wrong way but it surely won't matter if the studs are at 16 or 24 really in the big scheme of things if you have planned for 16 just stick to it and get on with it!!

JG

Thanks, John. I hope I'm able to "get on with it" here, but I respect what Steve has to say. I agree that if it's only a 1 or 2 db difference, I will screw it (literally and figuratively ) and move on. However, I am concerned about the safety/stability/legality of my beef-up fasteners and I won't move another muscle until I resolve this latest stumbling block.

As for the 1,000 posts... Just paying it forward, my friend. I figure the more I help others (or help confuse others as is regrettably sometimes the case ), the more I'm able to draw from the help pool when needed.

And right now, needed!

Thanks for the encouragement...

--Keith

Just for the record I think that the effort and time you put into this board is superb. I am sure that once your room is done it will be totally fanastic. There has been many occasions where I have asked something and you have helped out and I wish I had the knowledge to do the same back. I ended up getting so confused at the different info I was getting I paid for John to look over my plans and point me in the right direction. There are several things I am doing in my own room the are judgement calls so I always still ask a few questions.
Keep up the good work.
JohnG

Keith Sharward is definitely rookie of the year. You took it all the way, and you should be proud. DO NOT lock yourself in the room. Im sure knowone will hear you...

Help! I need to know whether I need to call off the delivery of my 1,906 pounds of drywall on Friday morning!

Keith, you're right; musta been a combination of me posting right after last graveyard shift and being under the (weather) gun around here.

Your beef-up layers would work better if they are only fastened around their perimeters - this lets each layer maintain its own coincidence dip. However this would require a way to keep the perimeter edges tight against each other, so either screws thru into the OSB layer or removing the first cleats(holding the OSB) and doing full-width gypsum inserts (all the way to the stud) with one FINAL cleat to hold it ALL against the outer leaf -

Eric Desart has cautioned against full-face gluing of gyp layers repeatedly, because it makes all layers act as ONE and lowers the coincidence frequency - this in turn weakens ISO at a lower frequency, which is ALREADY hard enough to deal with. Keeping the coincidence higher up in frequency makes it easier to stop with m-a-m, since this places the weakness further away from the resonant point.

My recommendation for using gypsum or other inserts would be to cut each insert to approx. 1/8" undersize and use a compressible, SLOWER setting glue around the perimeter(ONLY) - if you can't work fast enough to place ALL the layers you intend to use at the SAME TIME and then cleat the ENTIRE STUD BAY at once, you can instead use screws to TEMPORARILY place cleats until the glue dries - These should be angled toward the outside of the wall so they tend to PULL IN the cleats against the inserts, making a tighter glue line - this will lessen the chance of a gap between layers caused by glue not squeezing out enough.

Once your last layer of insert is done within a stud bay, the cleats can be permanently fastened; again, I'd use screws and angle them so they pull the cleat tight against the last insert.

I know this is a major PITA, but you need to avoid fasteners anywhere but the perimeter of the inserts for best low frequency attentuation - According to my Insul calculator, critical frequency (coincidence) of 1/2" gypsum is 3038 hZ; increasing this to 5/8" lowers coincidence to 2531 hZ, and 3 GLUED layers of 5/8 (same as one single layer of nearly 2") lowers coincidence to 843.8 hZ - 4 GLUED layers and you're down to 632.9 hZ.

The coincidence of INDEPENDENTLY ACTING layers doesn't shift whether using one layer or 10 - it's a function of the thickness of the contiguous layer, not the total.

As stated in one of your(or Dan's) threads at Studiotips, properly filled gaps around edges won't be the end of the world; but placing fasteners anywhere but around the edges WILL negatively affect your attenuation.

I need to go for now, if this is still confusing (or you want some ideas) just say so here; I'll check back tonight and if necessary post a sketch - Steve

I still think I'd do ALL the demo work and pour the new floor BEFORE starting this...

knightfly wrote:Keith, you're right; musta been a combination of me posting right after last graveyard shift and being under the (weather) gun around here.

Whew! You had me really worried there!

Your beef-up layers would work better if they are only fastened around their perimeters - this lets each layer maintain its own coincidence dip. However this would require a way to keep the perimeter edges tight against each other, so either screws thru into the OSB layer or removing the first cleats(holding the OSB) and doing full-width gypsum inserts (all the way to the stud) with one FINAL cleat to hold it ALL against the outer leaf -

I think I'm better off leaving the cleats in place. The reason is that the gaps between edge of OSB and edge of stud varies widely, from 0 to 3/8" and even 1/2" in a few spots, mostly due to stud imperfections (warped, twisted, waned, not plumb, etc.)

Eric Desart has cautioned against full-face gluing of gyp layers repeatedly, because it makes all layers act as ONE and lowers the coincidence frequency - this in turn weakens ISO at a lower frequency, which is ALREADY hard enough to deal with. Keeping the coincidence higher up in frequency makes it easier to stop with m-a-m, since this places the weakness further away from the resonant point.

OK, I'm down with that... Green glue on final two layers notwithstanding...

My recommendation for using gypsum or other inserts would be to cut each insert to approx. 1/8" undersize and use a compressible, SLOWER setting glue around the perimeter(ONLY) - if you can't work fast enough to place ALL the layers you intend to use at the SAME TIME and then cleat the ENTIRE STUD BAY at once, you can instead use screws to TEMPORARILY place cleats until the glue dries - These should be angled toward the outside of the wall so they tend to PULL IN the cleats against the inserts, making a tighter glue line - this will lessen the chance of a gap between layers caused by glue not squeezing out enough.

Once your last layer of insert is done within a stud bay, the cleats can be permanently fastened; again, I'd use screws and angle them so they pull the cleat tight against the last insert.

I'm afraid I'm not clear on this. Maybe if you just described it some more...

I know this is a major PITA, but you need to avoid fasteners anywhere but the perimeter of the inserts for best low frequency attentuation - According to my Insul calculator, critical frequency (coincidence) of 1/2" gypsum is 3038 hZ; increasing this to 5/8" lowers coincidence to 2531 hZ, and 3 GLUED layers of 5/8 (same as one single layer of nearly 2") lowers coincidence to 843.8 hZ - 4 GLUED layers and you're down to 632.9 hZ.

The coincidence of INDEPENDENTLY ACTING layers doesn't shift whether using one layer or 10 - it's a function of the thickness of the contiguous layer, not the total.

OK. Got it. "Don't make one big fat beef-up thingy," and fastening the layers together in the center essentially does that.

I need to go for now, if this is still confusing (or you want some ideas) just say so here; I'll check back tonight and if necessary post a sketch

A sketch would be awesome, Steve, if that's not too much to ask!! But if you're very short on time, maybe you can just "talk it through" some more, and then I can ask for a sketch later if needed -- or I could sketch it and you can comment.

I still think I'd do ALL the demo work and pour the new floor BEFORE starting this...

(sigh) OK. I'll give this some thought. I have scheduled myself a four-day weekend, so I had planned to work on beef. The concrete work will require "my landscaper buddy" and his availability is tight.

Thanks, as always...

--Keith (the is back... Kind of! )

there are two competely different wall structures being talked about here. first i'm going to talk about the beef up on the existing stucco wall.

i think keith is alarmed at whether the plan to screw 4 layers of gypsum into 1/2 inch OSB will work, or whether the gypsum will tear out and fall down due to inadequate screw penetration.

1/2 inch penetration into OSB isn't much but if you do MORE screws than normal (every 3 inches even) wouldn't that make up for it?

in any case, keith's current plan calls for the last layer of gypsum to be screwed into the cleats instead of the OSB. shouldn't that hold everything together?

ideally i'd do it differently however, i'd add another cleat on the outside of the last layer of gypsum. actually i now after thinking of this PLAN to add another set of cleats to the outside of the gypsum.

is it possible that that much gypsum can put too much force on the outside stucco? that was another thought that crossed my mind. the gypsum is vertical and most of the weight is straight down. in an earthquake though this would change unpredictably.

i wonder if screws can be put thru the cleat into the OSB so that the OSB is actually mechanically attached to the studs. this would keep some of the forces off the stucco in the event of an earthquake.

the second wall we are talking about is the new stud wall. this is where i think all screws need to be in studs. the OSB here is unneeded and just makes it easier to mistakenly think you hit the stud when you didn't.

i don't see why fastening only around the perimeter requires removing the cleats, you can still fasten around the perimeter going with your current plan. but i agree with the ONE CLEAT TO RULE THEM ALL idea.

keith, i hate to say it but you probably ARE better off doing the floor first. that makes the most sense to me. i have the same feeling of conflicts arising around which job i WANT to do NOW vs. which one makes the most sense from a practical standpoint.

but be coldblooded about it. you know already about surprises ... who knows what will come up in the concrete phase.

d

Dan Fitzpatrick wrote:. . . i think keith is alarmed at whether the plan to screw 4 layers of gypsum into 1/2 inch OSB will work . . .

Actually, 3 layers screwed/nailed into 1/2 inch OSB, then 1 final layer of 5/8 screwed into the cleats (and possibly through to the studs).

in any case, keith's current plan calls for the last layer of gypsum to be screwed into the cleats instead of the OSB. shouldn't that hold everything together?

That's exactly what I'm asking.

ideally i'd do it differently however, i'd add another cleat on the outside of the last layer of gypsum. actually i now after thinking of this PLAN to add another set of cleats to the outside of the gypsum.

I suppose that wouldn't be a problem, except for the fact that I'll only have about 3/4" worth of stud left. I guessed I'd have to I rotate the 5/8" x 1 1/2" cleats 90 degrees so that they're flat against the final beef... Like this:

is it possible that that much gypsum can put too much force on the outside stucco? that was another thought that crossed my mind. the gypsum is vertical and most of the weight is straight down. in an earthquake though this would change unpredictably.

i wonder if screws can be put thru the cleat into the OSB so that the OSB is actually mechanically attached to the studs. this would keep some of the forces off the stucco in the event of an earthquake.

Remember, the gaps between edge of OSB and stud are up to 3/8" to 1/2" in some spots, so there's not much opportunity to drive a screw through the cleat into the OSB. The screw would, in most cases, miss the OSB altogether, or just barely hit the edge.

the second wall we are talking about is the new stud wall. this is where i think all screws need to be in studs. the OSB here is unneeded and just makes it easier to mistakenly think you hit the stud when you didn't.

Here's where I think there's a lot of confusion on everyone's part. Yes, we are talking about many different types of outer leaf walls:

• The "exterior stucco wall," which I've been calling the "east wall"
• The "back wall" (with the contractor graffiti all over it), which is the "south wall." My office is on the other side of this wall. It will be three-leaf due to the fact that I don't want to remove the structural OSB already in place. I will definitely wait until the concrete work is done before I beef up this wall with (hopefully) multiple (4?) layers of 5/8" drywall.
• The "right side" wall, which I've been referring to as the "west wall." It is 8 feet long and the laundry room is on the opposite side. Instead of stucco/styrofoam/paper, I'm dealing with 1/2" of drywall on the laundry room side.
• There is also going to be a new section of west wall that will extend into the garage. This wall will be entirely new construction and is represented in the framing illustration above as "Right Outer Leaf Wall from Outside."
• Completing the crooked rectangle is the "north wall" which will also be new construction.

Here's another look at the floorplan:

. . . you probably ARE better off doing the floor first.

I hear you, Dan... (And Steve...) Since I'm already figuring on postponing the south wall beef-up effort until the floor is done, I suppose I should postpone the east and (partial) west walls as well. Another advantage would be that the nuances of beefing can be argued here ad nauseum whilst I get jiggy with concrete...

Killing my delivery will take the pressure off.

Damn. I thought I'd be at least somewhat protected from this "flopping around like a fish out of water" syndrome, given the rather insane amount of planning I underwent!

--Keith

P.S.: Mike, lots of love for your sincere "Rookie of the Year" award remarks.

The following image is a repeat of the image above, Klooster-style.

What you're proposing (not the last drawing, it's not necessary to rotate the cleats like that) the number of layers you're planning will be heavy, but as Dan mentioned they will bear DOWNwards. Using a thin bead of glue around the inserts' perimeters AND screws into the OSB will work fine. You can't put screws much closer together though, you want to keep at least a couple inches between screw holes in the OSB for strength - with 4 layers, offsetting screws by 2" each layer you'd be limited to 4 layers. So each layer's schedule should not be closer than 8". The final layer being screwed to cleats should work fine, just be sure this doesn't cause any air gap between the last two layers.

I'm not sure why I didn't catch (or comment) on your 16" centers earlier - possibly exhaustion, seems like a good excuse - thing is, although a "floppier" wall with high mass is slightly better than a stiffer wall with the same mass, your level of "overkill" should negate 99% of any ill effects. IF you were doing just two layers of rock each side, I'd strongly suggest you change your inner frame to 24" centers.

As it is now, I doubt you could get yourself in trouble with neighbors even after breaking a dozen pairs of sticks and splitting a couple of heads... Steve

To keep your new walls "safe" while you demo the concrete floor, couldn't you get the cheapest plywood or even 3/8" drywall and lay it up against the new walls (long edge down) to make kind of a super baseboard that would absorb the damage and then be tossed?

It might cost a little but it would protect your walls from concrete splashes and the errant jack hammer.

PS: If you use a jack hammer to get out the old floor, start in the MIDDLE of the floor until you get the hang of it. Personal experience! Long story, don't ask!

len