Ceiling joists

[soundrick]

I'm building a live room and have a few questions about the ceiling:

The room is being built on a slab in a warehouse space. For the walls, we had drawn up a staggered stud double wall on 2x6 plates, however I have been convinced of the virtue of going with a true double wall construction.

My question is regarding the ceiling joists. Do they lay across BOTH top plates of the double wall construction? If so, doesn't this couple the walls together?

If the suggestion is to build another lower ceiling with it's own joists under the "top" ceiling joists, that just eats up too much real estate.
I'm thinking if the joists connect the walls anyway, I might as well go with the staggered stud design.

Convince me!

Also, does anyone have any diagrams of ceiling construction like this?? I haven't seen anything that looks like what I picture........

cheers

[BriHar]

The inner walls should in no way be connected to the outer walls or the ceiling joists. The only connection to the outer shell will be the floor.
The new ceiling joists should connect only to the tops of the inner walls. These can run parallel to and inbetween the existing joists so as to not lose any height.
Check out Rod Gervais' book Home Recording Studio Build it Like the Pros.

[jhbrandt]

+1
.......AND you're going to need sway braces.

The devil is in the details.. and this is not all of them.

Cheers,
John

[soundrick]

I have Rods book, couldn't really find an answer or drawing on this specific question. His diagrams are all based on existing structures unless I missed something.

Anyway, I don't think I'm willing to give up ceiling height for this.

I think I'm just going with RC. For the RSIC clips, If I want to use 3 layers of 5/8" drywall and one layer Green Glue, I should be alright with clips 16" OC, yes?

[jhbrandt]

Rick,
Don't take anyone's word for it. Check the manufacturers documentation for spacing AND weight limitations.
Cheers,
John

Sent from my Galaxy Ace using Gearslutz.com

[mlange]

A true double-wall construction is completely free-standing. The slab floor is the only shared surface between all rooms. Don't stagger studs across a common floor plate.

I always think of a shoe box without a top. Turn it upside down and set it on the slab floor. This is what you want to build..... only larger.

(Sounds sorta like the Stonehenge scene in Spinal Tap, now that I've typed it.)

These construction methods really work when used correctly. 2-5/8 plus GG really works for me.

[Rod Gervais]

Originally Posted by soundrick

I have Rods book, couldn't really find an answer or drawing on this specific question. His diagrams are all based on existing structures unless I missed something.

Anyway, I don't think I'm willing to give up ceiling height for this.

I think I'm just going with RC. For the RSIC clips, If I want to use 3 layers of 5/8" drywall and one layer Green Glue, I should be alright with clips 16" OC, yes?

OK - seeing as you're saying you do not want to lose ceiling height to this - that means you plan on having the ceiling close to underside of the existing roof.

In that case your outer most walls should attach to the existing structure, which will also provide the necessary lateral bracing.

Your new ceiling frame should be attached to the new inner room frame - it should never make contact with either the outer assembly or the existing structure in any manner........

Now - what happens next depends on the existing structure...... if the structure above is concrete - then I simple add mass to the underside of the new ceiling assembly - the amount of mass being dependent on the level of isolation I require - considering (of course) the sound levels I need to deal with within the space.

However - if the warehouse is a simple butler type building (meaning steel superstructure with a simple corrugated steel skin, then things get different if you want to achieve any real level of isolation. In these cases I usually allow enough space between the old and new so I can apply some mass to the top of the new ceiling - which (even though it technically creates a 3 leaf system) is pretty much the only way to get any sort of good levels of isolation.

In almost all cases under these conditions I an using structural sheathing on the inside of all surfaces prior to the installation of drywall - this provides the necessary lateral bracing as well as some additional mass.

I also use structural sheathing on the top of the new ceiling frame.

Generally - if you have enough room up there to run the necessary mechanicals (ductwork and the like) along with room for the iso-boxes to maintain isolation levels for the duct penetrations.

As to the 3 leaf system I mentioned - I used this exact construction in Manila for the design of Studio H - a building with a tin roof - and achieved excellent isolation levels...... as I said in the book - we deal with what we have to deal with........

Rod

[soundrick]

Originally Posted by Rod Gervais

OK - seeing as you're saying you do not want to lose ceiling height to this - that means you plan on having the ceiling close to underside of the existing roof.

No, I'm just limited to a maximum outside height of 12' by the landlord, due to the fact that they're building an open storage area in the space above where the live room is being built (not coupled to the studio space).
The structures ceiling is actually probably more like 25ft to the truss. I am literally building a freestanding box inside this much bigger space, but my actual usable space is limited to the dimensions 18' x 18' x 12' sitting on a slab.

I can build anything within those parameters, but budget is pretty tight.

Would you say that staggered stud walls and RC ceiling is a good compromise between budget, space and isolation?