FLOOR/CEILING/WALL CONSTRUCTION SEQUENCE

luvshinerbock · Post by **luvshinerbock** » Sun Dec 07, 2003 8:38 pm

Hey-The holes on the RC don't line up either way I run them (across or along the runners). I guess I'm not really trusting the runners for stability, as the construction of the existing ceiling is old and the wood is dry and splits easliy if I screw too close to the edge (hence me placing screws where the 2x4 studs are, even if there are no pre-existing holes that line up with them). If I keep the screws a 1/2" to 3/4" IN from the edge than there is no problem with splitting. This still leaves me with a full 1" to 1 1/4" hanging out from the edge of the runner, so that there is no wood above where the drywall will be screwed in. [On that note, will the drywall screws go through the drywall AND penetrate the hanging RC without problems? It seems the RC section that hangs over is not sturdy enough to keep from bending up when trying to screw in the drywall (haven't yet tried, but...) Does the Drywall pressed up against the RC hold it in place enough that this isn't a consideration?]

In order to keep the leaf from being too stiff due to RC mounted too close, what do you think about mounting RC on two adjacent runners (12" space), then SKIP a runner and then run two more, etc. Could this cause complications when putting up the second layer of drywall? [should the second layer be placed perpendicular to the first?] On second thought, maybe I WANT a stiff spring in the control room, 'cause I'm trying to keep footsteps from upstairs from being heard...I don't know...one thing my physics teacher way back in High School used to say over and over was "The more you know, the more you know you DON'T know!" I'm feeling more and more retarded as the days go on.

Almost forgot--should ALL the pre-existing holes in the RC-1 be screwed? (I'm thinking, "Yes")

I'll put the GAF inBETWEEN the layers of drywall!

Thanks again Steve!
dean

knightfly · Post by **knightfly** » Sun Dec 07, 2003 11:12 pm

Man, you're up early for a Sunday - I'm on my way to the "DDJ" with little time, so I'll have to get this this evening, probably around 10pm your time, maybe a bit later - I'm not following how your RC can miss every stinking hole, can you post a pic of the stuff, laid next to a ruler or yardstick?

Old wood - it's a bitch. I'd get some adjustable depth screw pilot bits and sink some 3=1/2" #12 screws thru the flat runners into the joists - you MUST pre-drill and countersink, or else take the old stuff down and start over

Shoot a pic or two, maybe a rough drawing of exactly what you're trying to put where, you're losing me here... Steve

luvshinerbock · Post by **luvshinerbock** » Mon Dec 08, 2003 5:34 am

Sorry for the confusing post...what I meant to say was this: because the wood is old, I want to screw the RC through the runners and into the 2x4 studs. Placing the RC across or along the runners makes no difference, the holes don't line up with the 2x4s.

I'm outta time right now-get back to you tomorrow.

knightfly · Post by **knightfly** » Mon Dec 08, 2003 11:17 pm

"I'm outta time right now-get back to you tomorrow" -

Right back atcha - still don't understand what type RC you're using that doesnt have holes on 12,16,and 24" centers. If you could shoot a pic that shows about 2 feet of your RC alongside a clearly marked ruler or yardstick? Thanks... Steve

luvshinerbock · Post by **luvshinerbock** » Wed Dec 10, 2003 2:33 am

"...doesnt have holes on 12,16,and 24" centers. If you could shoot a pic that shows about 2 feet of your RC alongside a clearly marked ruler or yardstick?"

I'll try to get the camera again. In the meantime, the RC's holes are spaced 5 3/4" apart.

you MUST pre-drill and countersink, or else take the old stuff down and start over

Good enough. I will pre-drill...Do you still think that a stiff leaf on the ceiling of the control room (due to narrow spacing of the runners) is going to be an issue? I am only trying to knock down the sound of footsteps from upstairs.

knightfly · Post by **knightfly** » Wed Dec 10, 2003 5:26 am

Your RC will ease the stiffness, but not if it's too close together - that's a really odd hole spacing, you're right it wouldn't line up with anything NORMAL. Looks like you may have no choice but to put the screws through wherever your runners are. IF so, then we need to find out the recommended spacing/layer count - Do you have a manufacturer and or part # of your RC? Steve

luvshinerbock · Post by **luvshinerbock** » Wed Dec 10, 2003 9:34 pm

Do you have a manufacturer and or part # of your RC?

I'll get this information from the supplier today (Wed.). When I spoke with one of the salesmen about using it for the ceiling, he said that his "guys" put one layer of drywall up first and then the RC through the 1st layer of drywall and another layer on the RC. I said my application is different...anyway, I'll get back to you on the part#, etc...I wanna take a pic of this stuff so you can see it.

dean

luvshinerbock · Post by **luvshinerbock** » Wed Dec 10, 2003 11:48 pm

Steve,
It's Dietrich RC-1 (formerly Unimast)...I've been told that I don't need to use every hole, AND I don't need to use ANY of the holes as long as I'm driving a screw through the furring strips (what I've been calling runners) into the 2x4 joists. In fact they have recommended (for sound isolation) driving screws ONLY where the RC crosses the joists and no screws in between. You recommended 3-1/2" #12 screws in an earlier post...is this still the case (with a pre-drill)...been using 2-1/2"...I've only mounted three pieces, so I can easily fix those.

dean

knightfly · Post by **knightfly** » Thu Dec 11, 2003 6:03 am

Dietrich doesn't recommend their URC product for ceilings, only the RC Deluxe and the RC-2 (not my choice, less isolation with two legs) - can you pick yours out of these, or is it different yet?

http://www.dietrichindustries.com/bigdp ... sories.htm

On screw length/type, you want wood types for fastening the RC to the runners (furring strips), and to be safe you either need to use pilot holes and screws to fasten the furring strips better, or put screws clear thru the RC, furring strip, and at least 1" into the joist. If it were me, I'd do these operations separately - fasten the furring strips better with long screws, then use normal length (1-1/2" for ceilings) to fasten the RC to the furring strips. This will keep the extra tension of the furring strip screws from pulling through the thin RC metal. In every case, I'd drill a pilot hole that clears the body(minus the threads) of the fastener, or you'll have splitting problems with that old dry wood.

For mounting the wallboard to the RC, you need screws for STEEL - they need to be long enough to pass thru the RC by at least 3/8", in order to make sure they get good thread contact with the RC. Subsequent layers will of course need longer screws. Don't put ANY screws thru the wallboard where the furring strips are - you can use masking tape around the perimeter to mark these locations, then snap a chalk line ELSEWHERE for your fastener locations. Make marks that line up with those chalk lines also, so you can put your second layer's screws ELSEWHERE and avoid collisions.

But first, make sure WHICH RC you really have, and if necessary contact Dietrich directly for advice - each manufacturer has their own set of rules, and usually good reasons for them.

It amazes me just how FEW builders understand sound control though - (don't EVER put RC between wallboard layers unless there's no wallboard at ALL on the other side of the studs) you'd think that the isolation requirements for new construction would spawn at least a FEW education attempts... Steve

luvshinerbock · Post by **luvshinerbock** » Thu Dec 11, 2003 8:33 am

can you pick yours out of these

DIETRICH URC™ Resilient Channel-not recommended for ceiling. I'm going to have to look around to find something better, as most places only carry the above...

you'd think that the isolation requirements for new construction would spawn at least a FEW education attempts...

We're a lazy race, no?

I'm getting an education, though!

Thanks for the clear points on mounting the RC and wallboard! One other question...the second layer of wallboard should be put up...how? Offset by the first layer by a few inches? I've read the posts for WALLS, but is the ceiling a different beast?

knightfly · Post by **knightfly** » Thu Dec 11, 2003 10:50 am

Yeah, its number has been estimated at 666

The EDGES of the ceiling should go as I drew them,

http://www.johnlsayers.com/phpBB2/viewt ... c&start=45

with BOTH wall layers (or ALL of them) going ALMOST to the ceiling joists, but NOT touching them - then, BOTH or ALL ceiling layers stop leaving 1/4" gap to the wall layers, which extend ABOVE all the ceiling layers. (The RC takes care of this) Then, use acoustic caulking and seal all the gaps well.

The individual layers of wallboard, however, should NEVER coincide their mid-field seams in EITHER direction but be offset by at least a foot, preferably by one joist (either 16" or 24", whichever centers are used)

This means that for a second layer (assuming 24" centers and 48" wide sheets) you would start with a HALF-width sheet, placed at 90 degrees from the previous layer and offset lengthwise by one joist - then, subsequent joints will fall in the middle of previous layers' panels instead of being coincident.

This is definitely different than intersecting walls (other than the seam offsets, which should be done same as ceilings), which should alternate layers, being caulked as you go, so that the finish joint has a caulked, Z-shaped pattern for best isolation.

Even the wall/wall intersections should be gapped and caulked so there is no hard contact between intersecting walls though. By "wall intersection", I do NOT mean the continuation of a straight wall, but a place where two walls meet at an angle OTHER than 180 degrees...

The reason for ceilings being done differently is so that the ceiling wallboard can "float" inside the walls without settling and forming a hard contact between wallboard and ceiling panels. The acoustic caulk is flexible enough not to crack with quite a bit of settling, and should maintain seal.

However, if the wall/ceiling joint were "Z'd" same as wall/wall joints, settling could squeeze out enough caulk to form a hard contact and deteriorate the isolation between surfaces. That would reduce the isolation overall, partly because of one surface exciting the other un-necessarily.

Glad you're learning a lot - given enough beating of our heads on walls, this stuff finally starts to make sense (right about the time we need "rubber rooms" for something besides acoustic reasons

)

Hope you can find the RC Deluxe somewhere - besides the extra strength, it gives you a wider "target" to hit with your screw gun... Steve

luvshinerbock · Post by **luvshinerbock** » Sat Dec 13, 2003 5:08 am

I ordered the RC Deluxe and it should be in next week. I spoke directly with a Dietrich Industries regional sales rep. He was quite helpful. He even took the time to look at the pix I had posted on pg. 1 of this thread and gave me some feedback about mounting the RC (ACROSS the runners and along the joists).

Steve, do you snap a chalk line across the wallboard to know where the RC is? I'm going to rent a panel lift to do the ceilings.

First I need to finish the flooring, though. Do you recommend 3/4" on top of 1/2" (or vice-versa?)??? Can I put down 3/4", GAF and then the final flooring? The more I read the posts, the more conflicting info I get (kind of like some manufacturers recommend mounting the RC ALONG the runners on the ceiling and others just the opposite).

I now have the sequence of construction pretty much in my head through all the posts-thanks a boatload, Steve! One more question, though...windows. Should I have the windows in before the wallboard goes up? Or should I get the walls in place with the cutouts for windows and THEN install them? Does it matter?
dean

knightfly · Post by **knightfly** » Sat Dec 13, 2003 6:18 am

Flooring - I'd do the Gaf sandwich thing - are you floating this, or??

Windows - which windows, the one between iso and CR, or outside windows?

What did the Dietrich guy say about spacing of their RC for ceilings vs. # of layers? I've heard different versions and have not had time to conflab with them at all.

chalk lines - yes, definitely. before you put up the first layer, put masking tape strips on the walls, around the ceiling perimeter (or just mark on the wallboard) exactly where every framing member is on the ceiling (at least the furring strips and RC) then you can snap new chalk lines for each layer. If you snap a chalk line where the RC centerline is, then snap lines at right angles to that in increments of 12" (if that's to be your fastener spacing) - mark those on the wall (and label them) so you know where NOT to put screws for the NEXT layer. The second layer fasteners should be offset by 4", being careful NOT to allow fasteners over the furring strips. This requires planning ahead, and in the case of 3-layer ceilings you'd need to vary spacing to something other than even increments of 4" offset per layer, in order to MISS your furring strips completely on either side.

If all that's too confusing, yell and I'll do a basic drawing showing screw spacing layer to layer... Steve

luvshinerbock · Post by **luvshinerbock** » Sat Dec 13, 2003 10:00 am

Flooring - I'd do the Gaf sandwich thing - are you floating this, or??

Yes, I'm floating the iso room for sure-already framed and on top of the neoprene pads! And yes, I was planning on doing the GAF sandwich thing, but between WHAT? Two 3/4" layers? One 3/4" and one 1/2"? Or 3/8"? I've read in several threads of people using one layer of 3/4" others used 1 1/4" OSB or something like that, so I'm undecided.

Windows - which windows, the one between iso and CR, or outside windows?

Yes the window between the iso and control room...and well, the one between the iso and main room, too, for that matter.

What did the Dietrich guy say about spacing of their RC for ceilings vs. # of layers?

Basically he said that using the 16" OC joists for my situation is fine, especially with two layers of 5/8" and one 1/8" GAF--definitely not the 12" spacing I would have used had I placed the RC ALONG the runners. I think he said that 20-24" is for a "normal" application.

If all that's too confusing, yell and I'll do a basic drawing showing screw spacing layer to layer

It only took two readings to get that!
But, if you draw a picture my comprehension will increase tremendously. The various pictures and drawings on this forum (and others) have helped a great deal. Those pix/drawings combined with your text is a really good book waiting to happen! The Layman's Handbook on Studio Construction, by Steve Knightfly. (I'dda bought it!) I've skimmed the other books...too much info for someone like myself who doesn't have the burning desire to know WHY this method/material works, but just wants to know HOW to get er done! I'd rather read the manual for my Distressors and try to get a different effect out of 'em!!

More importantly I've begun reading the manual for my RADAR 24 and can't wait to finish construction so I can unpack that baby!

Steve, as always, I really appreciate all your great help here!

dean

knightfly · Post by **knightfly** » Tue Dec 16, 2003 10:18 pm

On most RC, 24" centers will support two layers of 5/8 sheet rock, so that sounds normal. I'd tighten it up since you're adding the triply, probably to 16" (just in case your ceilings don't cut sound enough to upstairs, you'll have the option of a third layer, preferably 1/2" if you have two 5'8" layers already up)

floor - are your 2x4's laid flat or on edge, and how far apart? That's one of the things more people forget to mention when describing things, is which way things are oriented and how far apart...

Hopefully I'll get a chance to work on a drawing tonite or tomorrow nite, it'll probably end up as a PDF file so if you don't already have Adobe Acrobat reader you should hit their site (adobe.com) and download the free reader (they don't show up on this site otherwise)

Running late for work, so I'll catch you later... Steve