Can anyone check my numbers before I create my practice room? (Sound proofing question, sorry)

KurtVerbose

Junior Member
Hi Everyone,

I've decided to take up the drums again after a break of more years than I'd like to admit to, and so far have found this website invaluable - so big thanks from me.

I know soundproofing has been done to death on this forum and it is very annoying when someone asks if egg boxes will work, but I'm about to create my practice room and am a little unsure if I have the numbers correct.

Firstly, this is just a practice room, so I'm only at the moment concerned with sound proofing, not sound absorbing.

Secondly, I live alone in a stand alone house, so I don't care if the noise carries throughout the house, but I don't want my neighbours to hear, even if I play in the middle of the night.

Ok, so here's what I have. This is the room I'm thinking of using, it's a small room 2.7 m by 2.5m (9ft * 8ft) that joins my garage to my house and it's made of solid reinforced concrete, like the garage. The walls are 25cm thick (10 inches) and the ceiling is 30cm thick (12 inches).

RoomFromBathroom.jpg


This is the doorway going into the house.

DoorToHouse.jpg


And this is the doorway going to the garage, the doorway on the left.

DoorToGarage.jpg


I think for both these I can put two thick sealed doors made of fermacel (gypsum board) either side of a 25cm (10 inch) gap - the thickness of the walls.

The door to the garage is far back from the entrance of the garage, it's where the red cross is in this picture. The front of the garage is some 11m (36ft) towards the camera.

DoorInGarage.jpg


Panning out you can the proximity to the neighbours to the left.

DistanceToNaziNeighbours.jpg


Drums are probably 120db when they hit the door/wall of my garage. If the doors are STC 60 it's going to be about 58-60db in the garage. Walk the 11m out of the garage and turn 90° and then another 6m (20ft) to my neighbours and it's likely to be only 22db, which I think will be ok. There is a garage door, but it doesn't perform anything much in the way of sound proofing.

My neighbours the other side are much further away. I've put a red cross where the practice room would be.

FrontOfHouse.jpg


The sound would have to go through the 25cm (10 inch) concrete, travel through 3 m (10ft) of air, turn 90° and then travel another 15 metres (50ft) which again would put it at about 23db by my calculations.

The other door in this room is to a very small room with some heating plant in. The heating plant has pipes that go through the wall to the house and there are some holes drilled that don't have pipes in them. I've marked with an arrow where the pipes are. I plan on rigging up the ventilation through here.

HolesInMachineRoom.jpg


These are the pipes from the other side - in the house. Notice the proximity of the window, which is double glazed.

HolesAndBathroomWindow.jpg


I will try and plasterboard over this. This floor is scheduled to be refurbished next year anyway when this will all be panneled in and insulated, for warmth as well as sound.

This is the window from the outside.

BathroomWindowFromOutside.jpg


Panning back you can see the proximity of my neighbours to the rear, about 7m (23ft) from the window, and again the path isn't direct as there's the concrete in the way.

DistanceToRearNeighbour.jpg


The practice room is directly below the red rectangle in this picture. As you can see, one side of the practice room is underground. Please forgive the state of the terrace, it's due to be decked next year.

FromTerrace.jpg


Ok, now my questions. Two layers of gypsum board have an STC of 55-57, so that would seem to be the weakest point of my room. That STC is at normal frequencies but the low frequencies of bass drums I've heard I might only get an 18db reduction, and even the concrete will reduce by only a little over 30. This would throw all my calculations out.

Also, what is the STC of concrete? I can find it for 8 inches, but not 10 or 12.

If anyone has any experience, knowledge I'd be grateful for you feedback. I don't want to do the doors and then find the room is really unsuitable.

Thanks,

Kurt
 
Crikey, you live in a bunker :)

Hang some heavy fabric drapery on all those walls and across the doors and not much will get out.

at the moment concerned with sound proofing, not sound absorbing.

If you absorb the sound, it can't go anywhere......right?
 
Doing the calcs might be fun and somewhat useful but I think the reality is that you do have a bunker there. Any way to test it as it is now? Maybe with a loud power tool (chainsaw, leaf blower) in the room and the current doors closed? Cant imagine you would need any more than another door to the garage myself. Maybe bring a snare and kick in there and listen outside while someone plays?

I would be more concerned about the acoustics of playing in that space with all the hard concrete surfaces.

Looks like a cool place with lots of toys (car boat drums). Great post with tons of pics too..
 
Any way to test it as it is now? Maybe with a loud power tool (chainsaw, leaf blower) in the room and the current doors closed? Cant imagine you would need any more than another door to the garage myself. Maybe bring a snare and kick in there and listen outside while someone plays?

It's a good idea. I'd certainly be able to test if the concrete kills enough of the sound. I'll try to borrow a bass drum, and failing that move my hifi there. I have power tools, but they're nothing like as noisy as a drum kit.

I would be more concerned about the acoustics of playing in that space with all the hard concrete surfaces.

Yes, they're likely to be horrible. What'll do is start playing and then add some sound absorbing stuff as necessary. I think the point at the moment is to start playing though. I haven't played so long I'm likely to sound awful anyway!

Looks like a cool place with lots of toys (car boat drums motorcycles girlz). Great post with tons of pics too..

Thanks for the feedback. Appreciated.
 
It seems to me that one you install your double doors, the only real issue would be the ventilation and whether that needs to be dealt with somehow [if it vents directly outside].

I'm kind of in the same predicament as you are [your house and the construction even looks similar to what I'm finding], as I'm currently looking at homes and coming across a lot of the same thing [minus the attached garage]. Finding great basements, ready for conversion, all concrete, and thick. I currently practice in an actual WWII bunker, and while it's great, it's also brutally cold in the winter. Ridiculously thick walls....so thick you can't hear anything while standing directly in front of it.
I think the advantage you have is that the house is stand-alone, so you won't be sending too many low-frequency vibrations through the frame to another. I wouldn't even think you'd have too much leak inside the house, since your practice room roof is on the outside of the structure, and not part of the interior of the house.
22db is really really low, and shouldn't be a problem for most neighbors, I would think. And 120db of live volume, even in that room, to me, sounds a bit high. But that's the one you want to be high, because if you play lower, it'll only affect your calculations in a good way.

Here's a question: how hard is it to get through that concrete? I'm going to eventually want to put 8 channels of line through the wall [hopefully]. Or am I looking at external conduits and boxes?
 
I would think not a whole lot is getting past 10 inches of concrete. I'll bet if you put in a solid door and plugged up any vents while playing you would not hear a whole lot if anything outside of the house and maybe not much inside the rest of your house.
 
Here's a question: how hard is it to get through that concrete? I'm going to eventually want to put 8 channels of line through the wall [hopefully]. Or am I looking at external conduits and boxes?

A guy came along with the correct tool and it took him just a few minutes to drill several 8cm holes.

Something like this: -

rems-picus-s1-aktion-1_702e2e8b-e8ed-4edb-a2b0-b912de49388d-250x250.jpg


Of course, if you need a bigger hole, you may need a bigger machine: -

drilling_n2.jpg


I'd be interested to find out how thick your concrete bunker is? I guess pretty thick. :)
 
A guy came along with the correct tool and it took him just a few minutes to drill several 8cm holes.

Something like this: -

rems-picus-s1-aktion-1_702e2e8b-e8ed-4edb-a2b0-b912de49388d-250x250.jpg


Of course, if you need a bigger hole, you may need a bigger machine: -

drilling_n2.jpg


I'd be interested to find out how thick your concrete bunker is? I guess pretty thick. :)

Cool...thanks for the info. I've seen those around. I'll have to get ahold of one and make some holes.

I'll also take pics of the bunker when I'm down the this weekend. It's pretty cool. I'll measure the walls, too.
 
A normal hammer drill will go through concrete as long as the bit is long enough Mikey- otherwise rent an industrial (Hilti is the brand that I have) rotary hammer drill and bit- they come in sizes 1/4" through about 3" so you should be able to drill a hole for wiring easily.
 
A normal hammer drill will certainly easily go through concrete, but if it's reinforced it will stop as soon as you hit the steel. There are drill bits that will go through this though.
 
Back
Top