John Sayers' Recording Studio Design Forum Archive

Thanks Andrew and Steve,

Steve - sorry can't get into the roof without smashing a hole in the ceiling but I'll see if I can get a few shots inside and out of the building for you to picture the structure.

I was thinking that if I added a new ceiling with 45mm x 90mm joist, even with only one layer of gyp board at least I could stuff the cavity with rockwool and seal the joins. The weight on the new joists won't be that great and the walls/floor will ge taking it all anyway. Most houses in New Zealand are compleatlly over engineered anway.

In terms of the floor, I,m counting on the majority of the sound going down through the existing floor on piles and being soaked up by the ground about one foot beneath.

That will still give me a room height of just over 7foot and fairly good isolation all sides and up which is probally the best I can do in the situation

I suppose I could do like Andrew suggested and add another one layer of Gyp to the existing ceiling get into the roof and insulate the cavity above my live room but The attic space is really small and there's no man hole.

I don't need 100% isolation but still want to be able to track when required.

Thanks

JohnG

When I suggested another layer on the ceiling I wasn't counting on the ceiling being 2x4's. It's really a good idea (as Knightfly suggested) to check the engineering loads permissable on different size studs. You don't want the ceiling to fall down and kill you. That would really suck.

No Problem, Ill see what I can do:

JohnG

Span limits for US 2x4's, which are really 37mm x 90mm, when putting more than one layer of gypboard on ceiling joists -

Assuming #2 and better grade Douglas Fir, using 24" centers the allowable span for 10 pound dead load is only 7 ft 3 in - for 16" centers, it goes up to 8 ft 11 in. - these spans go up to 9 ft 10 inches for 5 pound dead load with 24" centers, and 11 ft 3 in. for 16" centers - structure weight for this size framing can be estimated at 1 pound PSF, and 15mm gypboard at 2 pounds - so a double layer ceiling is just a bit over 5 pound dead load. If your timber is actually 45mm thick, you should have no problem spanning nearly 12 feet with two layers of 15mm gypboard.

If those 2x4's already there are part of rated truss assemblies, you will be OK adding a second layer to the existing ceiling as well - so if you build inner wall and ceiling frames, it looks like you can get your double envelope thing happening. That only leaves floor, windows, doors...

Also, when you're looking around at your floors, walls, etc, remember the mass-air-mass thing - it applies to ALL the parts of the building, including floors - we tend to discount floors since a lot of our members build in basements, and have this huge earth-backed concrete mass under them. In your case, however, if yours is on pole construction you may need to find a way to get that second mass with an air space between -

Very few of us (me included) can afford to do these things twice, that's why we take the time to ask/answer all these questions... Steve

Thanks Steve,

You are really a great help.

It seems obveious that with my limited ceiling height I cannot afford to float the floor 75mmmm and drop the ceiling 125mm.

Bearing in mind that the room is:

(1) built on 1 foot poles

(2) the existing ceiling is only finished with one plasterboard then attic then iron roofing

(3)I want to record acoustic drums

Do you think I would be better to:

(1) Add another layer of Gyp to the existing ceiling, insulate the attic cavity above the existing gyp and then float the floor.

(2)Leave the floor alone and "float" the new ceiling on the new walls

I suppose what I am asking is if I can't do both the ceiling and the floor because of space constrants what should I, in your opinion, attempt to soundproof/seal first.

My feeling is the ceiling and then if I still have a isolation problems I could atleast do something with the underside of the floor or build a small drum riser or both!!

Your opinion is appreciated.

JohnG

I'm still waiting to find out if your floor is just one leaf, or if there's a second center of mass (with air/insulation between them) - sound proofing is always limited by the "weak link" - if you're gonna leave the door open, why build STC 100 walls...

We need to approach this as a "system" - it's all or nothing unless you just like to spend money and hurt yourself

Do you have a way to do a basic sketch of your entire building showing everything that wasn't put there by mother nature? Until I can get a good grasp of EVERYTHING that's there, I can't say what will or won't work for you... Steve

Thanks Steve,

The floor is just one leaf of particle board flooring on top of concreate piles and timber joists. The building is solid and looks well built.

Heres the floor plan and side veiw of the structure you requested, Johns design for the space and my ceiling/wall plan.

Thanks

JohnG

More questions - will the new ceiling joists be 35 x 90, and will they be supported anywhere other than at their ends? If not, they will barely span 4 meters if placed 12" (300mm) apart, at at that would only support 1 layer of 15mm and 1 layer of 12.5mm gypsum.

Is there room enough under the floor to get under there and work at all? If so, you might be able to get your second leaf without cutting down headroom - otherwise, you could use flat laid 2x lumber floated on EPDM with two layers of plywood over, filled with rockwool to cut resonance - it's likely you'll need 35mm x 140mm ceiling joists rather than the narrower ones; those would span 5 meters used on 400mm centers and be able to support two full 15mm layers of gypsum. Doing that would cut your headroom down by about 250mm total, floor and ceiling changes included.

For your existing walls, that thin gypsum needs to come out if you are to kill drums and bass - you could either add a second layer of weatherboard outside (if that would work, and be sealable) or cut gypsum layers and glue/cleat/screw them against the inside surface of the outer weatherboard, then nothing on the inside of that frame and a double layer of gypsum on your inner wall.

Alternatively, you could do both sides of your outer wall heavily, and NOT seal your inner splayed walls (except between the drum room and CR, of course)

Can you take a picture or draw a sketch of what you call a "pile" ? I'm wondering if we're translating correctly here... Steve

This is a very interesting question about whether to do the floor or the cieling. My gut feeling is the floor because the drums are on the floor and there are other impact sounds on floors like footsteps.

One thing for sure is that your wall/ceiling detail will NOT work as drawn. You are asking the gypbd to cantilever a full joist space...will not happen. Your options, depending on whether you erect the floor or ceiling first, are: