Drywall questions

[Oldmate30beers69]

Hey guys, I'm building a studio that will be used primarily for drumming and rehearsals, a little bit of recording. I don't have any neighbours but I'm still trying to reduce the amount of sound getting out. I've got a double stud wall set up with foam underneath the internal wall to isolate it from the flooring.

Now my question is this. I can do a layer of acoustic drywall (soundchek we call it here in aus) for around 2k, or a layer of the fireproof stuff for a bit cheaper. I could do 3 layers of regular sheets for less again. What would give me the most attenuation do you think?

 

[Slouching Raymond]

You could try cement board. Heavier than plasterboard. Costs more though.
The heavier your board, the more it stops noise.

 

[Papanate]

Hey guys, I'm building a studio that will be used primarily for drumming and rehearsals, a little bit of recording. I don't have any neighbours but I'm still trying to reduce the amount of sound getting out. I've got a double stud wall set up with foam underneath the internal wall to isolate it from the flooring.

Now my question is this. I can do a layer of acoustic drywall (soundchek we call it here in aus) for around 2k, or a layer of the fireproof stuff for a bit cheaper. I could do 3 layers of regular sheets for less again. What would give me the most attenuation do you think?

3 Layers offset by 2 inches - so 9 inches total - would give great isolation - but drywall alone is not enough - especially if your walls are parallel - you should put up deflecting panels as well - the sound can’t travel far with these in place.

 

[ecc83]

To some degree walls are the easy bit! The ceiling and roof can leak a lot of sound and you cannot just go gaily adding mass there without consulting a structural engineer.

"Foam to isolate the floor"? How so? the floor need to be totally decoupled from the walls with proper elastic joist hangers AFAIK. For wood that is. If a concrete floor the wall must be "floated". You can stop a great deal of drum noise from entering the floor however by putting the kit on a platform of about 250mm height made of timber and flooring grade chipboard and filled with GF or RW. This 'plinth' floats on rubber blocks.
You can even utilize the plinth as a "diss board" and fit mains outlets and XLRs/jacks for mics and headphones...there's tidy isn't it!

Dave.

 

[rob aylestone]

One studio I built I put neoprene acoustic decoupler strip under the bottom timber. A few years later it got demolished. That foam had compressed from it's 6mm down to a thin hard (and pointless) hard lump!

Loads of people swear by green glue. I used it once and I vowed never to repeat it. The damn stuff is messy and yukky - and I'm not certain it did much. After all, you can't build a room, test it, then re-build it with the stuff to hear the difference? One studio I did was free-standing with all it's sides exposed. Inside and out were 2 x 9mm plasterboard on the timber studs, but withe an extra layer of 12mm MDF on the inside - because not only is it heavy and dense, it resists flight cases bashing into it, and doesn't damage easily with office type chairs - plus, you can screw into it anywhere - so guitar hangers, shelving, brackets, that sort of thing can be done anywhere.

What I did when it was done was go around the outside walls and the ceiling with a mic connected to headphones and play very loud music inside. The idea was to see how much leaked through the walls and ceiling. The results were very odd, and not what the books on the subject suggested. The leakage through the 2 layers of PB on the outside and the 2 layers of PB and one layer of MDF on the inside was very, very low. Nothing above 200Hz I could detect, and the very bottom - kick drum and 5 string bass B string detectable but not an issue at all. The ceiling which was just 2 layers of PB on the inside and 2 on the outside topped with ½" chipboard - was nearly as good. The snag was at the top edges where ceiling and walls met. Somewhere there there was midrange escaping. I could not localise it on the outside, but making noise on the outside and listening inside worked - It was where the layers of ceiling plasterboard touched the top of the walls. These had been cut to match the angles and the sound escaped through the tiny gaps, and with the ceiling joists on the top of the top timber, in to out were in some places just two layers thick, based on the exit route through gaps.

I cured this in the next studio by not putting the ceiling up the same way. Did the walls, and then put the first ceiling layer on top of the walls, and then the supporting joists on top - so the wall/ceiling joint is the same thickness as the rest. Since then, I now always do this and leakage is minimal.

 

[Oldmate30beers69]

To some degree walls are the easy bit! The ceiling and roof can leak a lot of sound and you cannot just go gaily adding mass there without consulting a structural engineer.

"Foam to isolate the floor"? How so? the floor need to be totally decoupled from the walls with proper elastic joist hangers AFAIK. For wood that is. If a concrete floor the wall must be "floated". You can stop a great deal of drum noise from entering the floor however by putting the kit on a platform of about 250mm height made of timber and flooring grade chipboard and filled with GF or RW. This 'plinth' floats on rubber blocks.
You can even utilize the plinth as a "diss board" and fit mains outlets and XLRs/jacks for mics and headphones...there's tidy isn't it!

Dave.

Thanks for the reply Dave. Drum riser diss board is a fantastic Idea. Was of planning on a riser anyhow so I will use that. The floor is wooden sheets, installed so as not to touch the outside walls and isolated from the floor with neoprene foam. The ceiling will be just 1 layer of fire rated drywall, the furring channel will be mounted on the acoustic hangers, same as the top of the internal wall

 

[Oldmate30beers69]

One studio I built I put neoprene acoustic decoupler strip under the bottom timber. A few years later it got demolished. That foam had compressed from it's 6mm down to a thin hard (and pointless) hard lump!

Loads of people swear by green glue. I used it once and I vowed never to repeat it. The damn stuff is messy and yukky - and I'm not certain it did much. After all, you can't build a room, test it, then re-build it with the stuff to hear the difference? One studio I did was free-standing with all it's sides exposed. Inside and out were 2 x 9mm plasterboard on the timber studs, but withe an extra layer of 12mm MDF on the inside - because not only is it heavy and dense, it resists flight cases bashing into it, and doesn't damage easily with office type chairs - plus, you can screw into it anywhere - so guitar hangers, shelving, brackets, that sort of thing can be done anywhere.

What I did when it was done was go around the outside walls and the ceiling with a mic connected to headphones and play very loud music inside. The idea was to see how much leaked through the walls and ceiling. The results were very odd, and not what the books on the subject suggested. The leakage through the 2 layers of PB on the outside and the 2 layers of PB and one layer of MDF on the inside was very, very low. Nothing above 200Hz I could detect, and the very bottom - kick drum and 5 string bass B string detectable but not an issue at all. The ceiling which was just 2 layers of PB on the inside and 2 on the outside topped with ½" chipboard - was nearly as good. The snag was at the top edges where ceiling and walls met. Somewhere there there was midrange escaping. I could not localise it on the outside, but making noise on the outside and listening inside worked - It was where the layers of ceiling plasterboard touched the top of the walls. These had been cut to match the angles and the sound escaped through the tiny gaps, and with the ceiling joists on the top of the top timber, in to out were in some places just two layers thick, based on the exit route through gaps.

I cured this in the next studio by not putting the ceiling up the same way. Did the walls, and then put the first ceiling layer on top of the walls, and then the supporting joists on top - so the wall/ceiling joint is the same thickness as the rest. Since then, I now always do this and leakage is minimal.

Interesting point about the ceiling, do you have any pics of that? I was considering 2 layers of 10mm plasterboard and a layer of 12mm ply which would cost the same as 1 layer of soundchek plasterboard

 

[Oldmate30beers69]

To some degree walls are the easy bit! The ceiling and roof can leak a lot of sound and you cannot just go gaily adding mass there without consulting a structural engineer.

"Foam to isolate the floor"? How so? the floor need to be totally decoupled from the walls with proper elastic joist hangers AFAIK. For wood that is. If a concrete floor the wall must be "floated". You can stop a great deal of drum noise from entering the floor however by putting the kit on a platform of about 250mm height made of timber and flooring grade chipboard and filled with GF or RW. This 'plinth' floats on rubber blocks.
You can even utilize the plinth as a "diss board" and fit mains outlets and XLRs/jacks for mics and headphones...there's tidy isn't it!

Dave.

Sorry, can you also explain GF or RW? Apologies if these are common terms, I'm a noob around here

 

[rob aylestone]

Glass fibre or rockwool is what Dave means. Pics wise I didnt take any of the actual building, sorry. Plasterboard here in the UK is quite cheap compared with plywood. Its crazily expensive, and sometimes the non-marine types are a bit variable in usefulness for sound. Compare the weights. The actual material used for the layers is sometimes very lightweight and has voids. I have never used the audio type of plasterboard. I looked at the specs and they seem to be aimed at use for reducing speech type frequencies for party walls and offices with some kind of thin extra layer. The specs dont show much benefit for music as the bass is the one that needs control and that comes from density, weight and thickness. Adding extra layers is always effective. Its also important to stagger joints so you never get two together, which is what happened at the corners. I did do one studio that was pretty good but after a year people next door started to complain about leakage. We stuck a smoke machine inside, filled the room and then spotted a leak. Somebody had installed a break glass fire alarm inside, and just drilled through every layer! Luckily we could bung up the holes on the inside and outside with hard setting filler which worked. I did another that used large patio style doors and discovered that the frames were not real solid wood, but plastic with thermal airgaps inside, and these let bass through quite well. That one could not be fixed without replacing the things and there was no money. All the ones i have done have had concrete floors, so i have not had any experience with timber floors so cannot advise there, apart from worrying about the weight of a room within a room standing on timber joists i have not see how they are fixed.

 

[ecc83]

SORRY about my "abrevs"! Yes Glass Fibre (correct spelling!) and Rock Wool. Glad you like my "riser diss board" idea, you can do the same with GOBOs* ? Have mains and audio panels on the inside, anything that minimizes cabling on floors has to be a good thing in my book.

Robs point about sound leakage should be well considered. I recall from a book on acoustics I read years ago that if you drill a 1/2" hole in a 50ft single course wall, AS MUCH sound comes through the hole as from the entire rest of the wall. (I may not remember the exact numbers but I think you get my drift? NO HOLES!)

*In case we have another language problem? "GOBOs" is the name for acoustic panels that can be placed around very noisy buggers like drummers and E gitists to cut a bit of their row. They can be simple ply or MDF panels or a sandwich of hard material and acoustic filling (GF or RW!) Opaque or with a double glazed window. Of course they can be used in the opposite sense? Put around a quiet thing like a classical guitar.

Dave.

 

[ecc83]

https://www.cef.co.uk/catalogue/products/29144-135mm-x-50mm-3-compartment-chamfered-dado-skirting-trunking-white-3m-length

WRT chairs etc bashing walls, if the above dado rail* is installed at chair back height that effects some protection.
I know you can safely run mains cable in the middle compartment and CAT cables in the other two but I would bet balanced lines and headphone feeds could go there as well. You could even try balanced mic lines? If carrying strong signals such as snare or crashes you could HPF and remove any hum but I doubt there would be much?

*What do our brethren across the Pond call it?

Dave.

 

[Oldmate30beers69]

SORRY about my "abrevs"! Yes Glass Fibre (correct spelling!) and Rock Wool. Glad you like my "riser diss board" idea, you can do the same with GOBOs* ? Have mains and audio panels on the inside, anything that minimizes cabling on floors has to be a good thing in my book.

Robs point about sound leakage should be well considered. I recall from a book on acoustics I read years ago that if you drill a 1/2" hole in a 50ft single course wall, AS MUCH sound comes through the hole as from the entire rest of the wall. (I may not remember the exact numbers but I think you get my drift? NO HOLES!)

*In case we have another language problem? "GOBOs" is the name for acoustic panels that can be placed around very noisy buggers like drummers and E gitists to cut a bit of their row. They can be simple ply or MDF panels or a sandwich of hard material and acoustic filling (GF or RW!) Opaque or with a double glazed window. Of course they can be used in the opposite sense? Put around a quiet thing like a classical guitar.

Dave.

I think that is the Rod Gervais book you're referring too? Great read. Thanks for the noob explanation too I had no idea what GOBOs were! I'm the noisy bugger in this sense so no need for them. I'm gonna build acoustic baffles and hang them on the walls just to tune the sound a bit but I guess that's all trial and error

 

[Oldmate30beers69]

Glass fibre or rockwool is what Dave means. Pics wise I didnt take any of the actual building, sorry. Plasterboard here in the UK is quite cheap compared with plywood. Its crazily expensive, and sometimes the non-marine types are a bit variable in usefulness for sound. Compare the weights. The actual material used for the layers is sometimes very lightweight and has voids. I have never used the audio type of plasterboard. I looked at the specs and they seem to be aimed at use for reducing speech type frequencies for party walls and offices with some kind of thin extra layer. The specs dont show much benefit for music as the bass is the one that needs control and that comes from density, weight and thickness. Adding extra layers is always effective. Its also important to stagger joints so you never get two together, which is what happened at the corners. I did do one studio that was pretty good but after a year people next door started to complain about leakage. We stuck a smoke machine inside, filled the room and then spotted a leak. Somebody had installed a break glass fire alarm inside, and just drilled through every layer! Luckily we could bung up the holes on the inside and outside with hard setting filler which worked. I did another that used large patio style doors and discovered that the frames were not real solid wood, but plastic with thermal airgaps inside, and these let bass through quite well. That one could not be fixed without replacing the things and there was no money. All the ones i have done have had concrete floors, so i have not had any experience with timber floors so cannot advise there, apart from worrying about the weight of a room within a room standing on timber joists i have not see how they are fixed.

There's no worries about wall weight in my build. It's a steel frame on steel piers dug 3 feet deep and concreted in. I've also got 2 layers of 19mm tongue and groove floor, rubber tape on the joists and acoustic underlay in between the layers. The only thing i am concerned with in regards to the room in a room construction is I've had to screw it to the existing frame up the top and feel like that will just transfer through. I've used the same rubber on the top plate that i used on the bottom plate so i hope it doesn't carry sound through. Thanks for the advice, I really appreciate it

 

[rob aylestone]

My first rule now is that predicting acoustic treatment is pointless. I finish the room then treat what I find. One thing I always do since studio 1, is never have 90 degree corners, and on longer walls I pull out the middle to help reduce parallel surfaces. Even a few degrees make huge differences. I also cut out MDF panels around 1m x1m and I attach these to the ceilings, to break the ceiling to floor parallel surface. They also cover unsightly vents, and are great places to mount downlighters. I spent quite a bit on the one with the neoprene, but never noticed any differences in the ones without - although I guess it would seal any ups/downs in the concrete floors? One trick I do do is lay the last layer of sheeting horizontally, not vertically. I then cover the join with timber 19mm x 100mm, and then I put an identical trip exactly a UK power socket/light switch height below it. My power and lights are then in the gap which looks nice and also does the chair protection. I found this old pic from the one with problem doors