Converting garage into rehearsal studio, Dublin, Ireland

[KickingTelevision]

Hi all,

I'm a first time poster, here, so I'll do my very best to supply as much information as I can and try and make it easy for all of us! However, if I leave out details, I apologise in advance. Similarly, I'm afraid that I don't posses the exceptional level of knowledge and intelligence on display, here, from all members of the forum when it comes to the science of sound and why a certain room produces the sound that it does; I know little, if anything at all, about "golden ratios" and the like, though I am sincerely trying to get my head around it all.

My project:

Basically, I am hoping to build a band rehearsal space to rehearse in with my band and record band rehearsals and demos for records. I don't believe that I would have the space needed for a studio: I think a live space and a control room would be a squeeze. The music that I play and the bands that I play in are 4 - 5 piece pop / rock bands.

Really, what I want to put in the rehearsal space is band equipment- guitars, amps, drums, cables, pedals, etc., etc.- ; PA's, monitors, live mixer; a desk and chair for a desktop / laptop and speakers; recessed, LED dimmer lights; a modest, LED light rig for rehearsing light shows; a couch; a wall- mounted whiteboard.

I live in a mid- terrace house in Dublin, Ireland. At the rear of my home, at the end of the garden, I have a small garage that, originally constructed in the 40's / 50's, I am going to demolish and re- build from scratch: the lean- to, asbestos roof is in tatters and the solid brick has seen better days. The cost of demolishing and re- building the garage isn't extraordinary and, for the extra cost, I think it will be worth it.

The garage has two entrances and one window: a large, garage door; a single door at the corner of the garage for entrance from the home; a window facing the garden. My plan is to replace the large, garage door with an Insulated Roller Garage Door. I think the roller door would be useful for loading and un- loading before / after gigs. I also plan to replace the single door with a hall door with strong soundproofing qualities (help needed on this) and to brick- up the window and have no windows, at all, in the rehearsal studio to avoid leakage, and instead put vents in the walls. The only other option with the window is to replace it with a triple or quadruple glazed unit, though I am not sure of the cancellation qualities of triple / quadruple glazed windows.

Living as I do in a terraced home in a residential area, my chief concern is sound cancellation so as to not annoy my neighbours! My friend, a trained and qualified builder, will be constructing the build and he aims to use gypsum board all over the walls and ceiling. Not that I'm an expert, but I believe the gypsum board that he intends to use has sound cancellation qualities of between 50 - 60 db. The bands that I play in usually range anywhere between 80 - 100 db; my aim, then is to cancel the sound down to 30 - 40 db.

Dimensions

The current size of the space is 11ft. x 15ft. with a ceiling height of 8ft. However, I expanding the 11ft width by 2 ft. and the 15ft. length is being expanded by 4ft.; 2ft. towards towards the garden / home and 2ft. on the alleyway / mews entrance as I am expanding the current, recessed entrance so that it is flush and in- line with other entrances on the alleyway / mews. According to Dublin City Council, the maximum height of an outhouse or garage, without having to go through the red- tape of applying for planning permission, is 13ft. I am planning to raise the the ceiling height by 3ft.

My intended dimensions for the rehearsal space, then, are 13ft. x 19ft. with a ceiling height of 11ft..

I also intend to put in a wooden floor and, perhaps, a floating floor at that.

Any and all thoughts, advice and recommendations would be greatly appreciated. Again, please excuse my basic, elementary knowledge on all of this; it's why I'm here!

Thanks in advance.

[JCBigler]

13' by 19' is pretty small for a full rock band rehearsal room. And 120dB is pretty damn loud. Is that an actual measured reading? with a reliable dB meter? And is that A weighted or C weighted? At any rate, I hope you guys are wearing ear protection at those levels.

I would suggest that both you and your builder get and read Home Recording Studio: Build it Like the Pros by Rod Gervais. It will explain all of the basics of studio design, constructions and acoustics. There's lots more to learn, but that's kind of the starting place.

Stick around here long enough and you'll learn that you don't want to do a floating floor, unless you have lots and lots of money to throw at it. A standard conrete slab with hard wood or laminate wood floor will provide a fine floor for your space.

How close are your neighbors? How loud is your band currently outside of your space? You will need multiple layers of gypsum board with Green Glue between them, and two leaf double wall construction in order to isolate 120dB.

[KickingTelevision]

Hi Justice,

Thanks for your swift reply and book recommendation: I just ordered Gervais' book.

My apologies: 120 db was a probably a wild estimate on my part! I just spoke to a couple of the guys in my band; they say it's nowhere near 120 db and more 90 db - 100 db. We had a meter reading a while ago and it came in at 95 db. We're rehearsing in our current, rented space, tonight, so we're bringing along a friend who has a meter to check our level. And yes, we all wear ear protection; I'm pretty strict about ear protection.

Neighbours are close enough, which is why isolation is such priority.

[Soundman2020]

Hi there "KickingTelevision", and welcome to the forum!

I'd add one more book to what JC said: I'd suggest two books: "Master Handbook of Acoustics" by F. Alton Everest (that's sort of the Bible for acoustics). Rod's book will give you all you need to know about how to build the studio, and Everest's book will help you understand why you do all those things, as it gives you the basics of acoustics.

Your first estimate of sound levels may have been a bit high, but your second estimate is low for sure. Here's why:

The music that I play and the bands that I play in are 4 - 5 piece pop / rock bands. Really, what I want to put in the rehearsal space is band equipment- guitars, amps, drums, cables, pedals, etc., etc.- ; PA's, monitors,

I've never met a rock drummer who can play quieter than about 105 dB, and most play around 110 to 115. So just the drums alone are going to be giving you well over 100 dB. Let's say 110 db, conservatively. Add in bass, electric, and keyboards, and you are easily pushing 113-115. 120 is possible, but unlikely. That would be insanely loud for a rock band, but then again I have heard plenty of "insanely loud" bands in my time! But it's at the upper limit of what you'd expect, and JC is dead right there.

As JC also said: there's an issue with how you measured your levels. You can't measure sound levels using your ears! That sounds silly, since sound is what ears measure, but there's a problem: human hearing is adaptive. It adjusts to the average level over a period of several minutes or so, then considers that that level is "normal". So there is no absolute reference point: it changes according to the ambient level. So you can't just estimate the level by mentally comparing it to other levels that you remember from other locations, since the brain and ear are incapable of doing that with even a vague level of accuracy. The only way to measure the level, is with a proper sound level meter. And "proper" does not include "an app I downloaded for free on my iPhone"! The mic and circuitry used in phones is totally inappropriate for measuring sound levels. You need a real sound level meter.

Then you need to set it correctly: It has to be set for "C" weighting, and "slow" response, because you are measuring loud levels. If your meter is set to "A" weighting, you are not measuring the level correctly, since "A" weighting is for low levels, not high levels.

So I'd encourage you to get a meter (decent ones go for about US$ 100 on e-bay and Amazon) and measure the actual levels in your room in a typical session, and also measure that same sessions from outside the room, with all the doors and windows closed. That will give you an idea of how loud you are and how much isolation you already have. Based on that you can figure out what type of construction you need to get the level of isolation that you need. Guessing at the materials and methods of construction is a really bad idea!

asbestos roof

Not sure about the laws in Ireland, but in most places that asbestos considered a hazardous material, and requires a qualified, specialized team to remove and dispose of. It's not something you can knock down yourself and throw in the trash, so you should budget plenty for that.

My plan is to replace the large, garage door with an Insulated Roller Garage Door.

If you are going to rebuild this place specifically as a studio, then why would you put a terrible acoustic isolator in as the main door? That would be shooting yourself in the foot before you even start. Forget about large doors, and limit all access to doors that can give you the high levels of isolation that you need.

I think the roller door would be useful for loading and un- loading before / after gigs

It would be useful for that, for sure, but the rest of the time it would be absolutely useless to keep the cops from handing you noise violation fines, and the neighbors from throwing rotten eggs at you each time you walk down the street...

In other words, forget the idea of roller doors. Not use at all for isolation. Instead, go with good isolation doors. They can still be plenty big enough to get your gear and instruments in and out.

I also plan to replace the single door with a hall door with strong soundproofing qualities

A single door is pretty useless here too, unless you want to drop a few thousand dollars / pounds / euros on a really massive purpose-built isolation door. The only other way of doing it, at a reasonable price, is to have two doors, back to back, with an air gap between them. That's the way studios are built, and there's a reason for it: it's the best and least expensive way of getting good isolation.

and to brick- up the window and have no windows

You can have windows if you want, provided they are done correctly. Glass is actually a very good acoustic isolator, since it is very massive. So as long as you build the windows the same as the doors (in pairs, back to back) and make the glass thick enough, then you can have windows. They cannot open, of course, but you can still have them for natural light, if you want.

and instead put vents in the walls

So you do not need any isolation at all then?

Any hole you put in your wall, even a very tiny one, totally destroys your isolation. Your room must be built as a totally air-tight, hermetically sealed place. Not even a tiny gap under the door. Everything must be sealed, for a very simple reason: if air can get out, then so can sound. Sound travels through air (that's the very definition of "sound" anyway"!) so even a tiny crack is enough for lots of sound to get through. If you don't believe me, then go sit inside your car in a noisy place, such as heavy traffic, with all the windows tightly closed. Now open your window just a tiny bit, so there is only a 1 mm gap at the top.... Case closed.

The only other option with the window is to replace it with a triple or quadruple glazed unit,

No, that's not an option. Three-leaf and four-leaf construction is WORSE at isolating low frequency sounds than two leaf construction. Not intuitive at all, but very true. 3- and 4-leaf glazing is great at stopping heat from getting in and out, but lousy at stopping low frequency sounds, such as drums, bass, keyboards, and such like. Once again, there's a reason why professional studios are built with 2-leaf walls: because it is the lowest cost method of getting high levels of isolation.

my chief concern is sound cancellation so as to not annoy my neighbours!

I think you mean "isolation" not "cancellation". Phase cancellation is an aspect of acoustics that can, under some circumstance, be used to reduce sound levels, but not for isolating entire rooms.

My friend, a trained and qualified builder, will be constructing the build

Great! You have free labour, and someone who understands construction materials and tools. Now all he has to learn is that building a studio is nothing at all like building a house, office, shop, or school: Many techniques normally used on building those are absolutely NOT applicable to building a studio, and cannot be used. Same materials, yes, and same tools, but the methods and techniques are very different. He'll first need to un-learn those, then learn the new techniques that studios need. If not, then you'll be wasting money, as your studio will not isolate well.

he aims to use gypsum board all over the walls and ceiling.

That's good, provided that it is done properly, and NOT in the way that houses etc. are normally built. The key to isolation is in these three things: 1) Mass. 2) Decoupling. 3) Air-tight seals. Normal construction methods do not use nearly enough mass, never decouple, and don't bother with air tight seals. That's why your friend will have to learn to do these things different ways, because the ways he knows already are not applicable to studios.

but I believe the gypsum board that he intends to use has sound cancellation qualities of between 50 - 60 db.

So does paper, if used correctly! In fact, even empty air can get your 60 dB of isoaltion, if you use it correctly... But you'd need hundreds of meters of it...

Gypsum board (a.k.a. "drywall", "plasterboard", "sheetrock", "wallboard", and others) by itself is not so good at isolating: A single sheet of drywall will get you exactly 27.3 dB of isolation, which is over one thousand times less isolation than 60 dB: Yes, literally a thousand times worse, because the decibel scale is logarithmic, not linear. Adding another layer of drywall to that will increase your isolation to about 31 dB, because a basic law of physics says that each time you double the mass of an acoustic barrier, you get an increase of 6 dB in isolation. That's for theoretical perfect mass: real life materials give you about 4 to 5 dB increase for each mass doubling.

So if you want more than 31 dB (what a typical house wall gives you), then you can take those two sheets of drywall and add another two, which doubles the mass, and you now get about 36 dB of isolation. Double again (total 8 sheets) gets you 41 dB. Double again (16 sheets) gets you 46 dB. Double again (32 sheets) gets you 46 dB... I think you can see where this is going. As long as your friend can figure out how to make your walls and ceiling out of 128 sheets thick of drywall, then yes, you'll be able to get 50 to 60 dB of isolation.

That's from using single-leaf wall construction, and also similar for fully-coupled 2-leaf, which is what your friend knows how to build for normal houses. But when he learns how to do to fully decoupled 2-leaf MSM construction, you actually can get 60 dB of isolation with much, much less drywall. In fact, if he does it right, then you can do it with only four sheets of drywall. But you have to know how to do it!

my aim, then is to cancel the sound down to 30 - 40 db.

that's roughly what a normal house wall gets, and you already know that it's nowhere near enough. In fact, the brick walls you already have are getting you about that level. So clearly, that's not the level of isiolation you need.

Assuming your band plays quietly, at around 110 dB, if you have 30 dB of isolation then you'll be getting about 80 dB outside your walls. 80 dB is about the level of a freight train running past 15 meters away, or a diesel truck driving past at 60 km/h 15 m away, or a leaf blower, or a food blender in the kitchen, or plan flying overhead at 300 m... probably not what your neighbors would consider "quiet" at 3 Am, when you guys are having a good time...

So it looks like you need substantially more than 30 dB of isolation. Your estimates are just a little off! 80 dB is also the level of a police whistle blown a few feet away form your ear, which seems somewhat appropriate....

I also intend to put in a wooden floor and, perhaps, a floating floor at that.

As JC already mentioned that would be a bad idea. Here's why: http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

Your very best possible floor is a plain old concrete slab on the ground. For good isolation at low cost, there is no better way.

so we're bringing along a friend who has a meter to check our level.

Excellent! Make sure it is set to "C" and "Slow". Measure both inside and outside while you are playing. Measure in many places in and around the property, especially the places closest to the neighbors. Make careful notes on a sketched diagram of the property, showing the level at each point. Then shut down the band, send them all home, wait for the quietest time of night, and go back to each of those points and measure the ambient levels. That's your goal. You have to get your level down to no louder than the ambient level. The difference between that ambient level and the loudest level you produced inside the room, is how much isolation you need. Based on that, you can find the type of construction and the materials that will get you that amount of isolation, then you can come up with your budget for the build, based on the cost of those building materials where you live.

Acoustics is a science. Lots of research has been done, and there are equations, methods, materials and systems for designing and building studios. But they are all based on numbers, not guesses. so we need to know what your numbers are (in terms of "how loud" and "how quiet") in order to be able to help you design your studio so that it really will achieve what you want.

So please post those numbers, after taking careful readings with your friend's sound level meter.



- Stuart -