Converting Metal Garage into Studio

[Sammy in Aus]

I am looking at turning a metal garage into a recording/rehearsal studio. It is to be for personal use so I can rehearse with my band without the neighbours complaining and also to be able to record good quality demos.

My major issue is that I am starting with a garage which is made from metal (walls and pitched roof) on concrete slab and I need to minimise noise getting to my neighbours but I am on a tight budget. My band can be loud (drums/bass/electric guitar and PA for Vocals)

I have been reading up on sound absorption and noise reduction but am still not sure what the best option is. My ideas are listed below:

1. (a) Line the Walls and roof with 3 -4 layers of carpet
(b) Build a room within this using isolated wood stud frame and line this with either 12mm MDF (fibre board) or Plasterboard (gypsum)
but i am not sure - which is better at reducing sound transmission MDF or Plasterboard?
(c) Fill gap between walls with some sort of insulation
(d) Roof to be built in same way as walls
(e) control room to be separated from live room using double wall construction

2. (a) Same as 1 accept line existing frame with 12mm MDF (Fibreboard) instead of using the layers of carpet. (this will be more expensive so I would prefer option 1.


I have started filling all gaps in between the wall metal sheets and the roof metal sheets with expanding foam. There is quite substantial gaps here as the roof sheeting is Corrugated (wave pattern) but the foam seems to work quite well.

So my questions are:

1. Is option 1 a valid solution or will I not get adequate reduction using carpet. ( i have read carpet is only good at higher frequency noise transmission reduction)
2. Will option 2 give me the result I need?
3. Is MDF (Fibreboard) and better to use than Plasterboard (Gypsum)?
4. Is the insulation between the 2 walls worth the cost?

Appreciate anyone’s help on this who has been through a similar experience or who can give me some advice. I have wanted a studio for so long – I want to make sure I get the best result I can.

Thanks,

[sharward]

Welcome to the forum, Sammy.

. . . Line the Walls and roof with 3 -4 layers of carpet . . .

Carpet = bad. 3-4 layers of carpet is bad to the power of 3-4.

Con't confuse isolation (soundproofing) and treatment (absorbtion to reduce echo and improve sound quality inside the room).

Please set aside a few hours to review the Reference Area thread, and be sure to follow all the guidelines in the "Before You Post" announcement.

[Sammy in Aus]

Hi sharward,

Thanks for the advice - will definately stay away from the carpet.

Does anyone else have any advise - i really need to make this thing work... we despretley need somewhere to rehearse and record.

I will update with some images in the next couple of days.

thanks,

sammy

[knightfly]

Sammy, the advice Paul gave you over on RO is very valid; there isn't a cheap way to get much isolation.

When you post pix, maybe something will come to mind that could help; but don't get your hopes too high, the physics are what they are and they require MASS and DESIGN to work... Steve

[Sammy in Aus]

Hi Steve and everyone,

Remember me - has been a while but i hope to get things moving again.... what i seemed to have established is that i have to do a Mass air Mass system where I add material directly to the existing metal shell giving me a heavier outer leaf and then build inner wall for second leaf.

I am OK with this but am still not sure on whether it will be enough to stop the nieghbors complaining? What do you think?

I would like to use 18mm MDF sheeting for my outer and inner leafs - is this as good as using 2 x 9mm Plasterboard/Gypsum?

Should ther inner and outer layers have a differernt thickness? (i have read contradicting info on this)

I have taken pics of my shed/garage and will post later this week to show everyone what i am starting with.

Thanks all for your help... really appreciate it.

Regards,

Sammy

[sharward]

. . . i have to do a Mass air Mass system where I add material directly to the existing metal shell giving me a heavier outer leaf and then build inner wall for second leaf.

'xactly.

I am OK with this but am still not sure on whether it will be enough to stop the nieghbors complaining? What do you think?

That all depends on what "it" is. More mass on each leaf will yield better results.

I would like to use 18mm MDF sheeting for my outer and inner leafs - is this as good as using 2 x 9mm Plasterboard/Gypsum?

I'm not the calculation guy here, but I think gypsum wallboard is (in the US anyway) the cheapest way to achieve mass.

Should ther inner and outer layers have a differernt thickness? (i have read contradicting info on this)

I too have seen the contradictions. I believe the mindset against having the same thicknesses on both leaves is that you end up with the same resonant frequency on both leaves, which could be detrimental. However, I think that if you aim for achieving enough mass to attack the devious "low end" frequencies and shoot for resonant frequencies below human hearing, that will be the governing factor. Let's see if the "real" experts here concur with that!

If there's anything I have learned here in the past six months, it's been that you cannot simply guess at the correct materials formula. You have to determine what sound levels you expect to generate, then determine what sound levels to aim to achieve after your project is complete. The difference between those two numbers (there are actually many pairs of numbers to get differences of, with the "low end" frequency number being the most critical) becomes your target. Then, you have to develop your plan to achieve that target number (and, practically speaking, probably a few db above that number, to account for construction mistakes and material imperfections) based on legitimate test results. Doing anything less than this is either a wild guess or an educated guess, but a guess nonetheless, and guesses in this business rarely deliver.

Fortunately, this forum is great for a lot of things, including getting help with those necessary calculations when needed.

You're now officially on the path to Soundproofing Enlightenment!

[knightfly]

Rough calculations - two identical walls, both with 2x4 stud double frames, 1" apart frame to frame, effective air(insulation) gap of 8" -

First wall - two layers 5/8 gypsum, 1 layer 1/2 gypsum each side - STC 75, TL @ 50 hZ 40 dB, coincidence dip @ 2500 hZ, 70 dB Slightly rounder dip than using all 5/8 - (surrounding TL values around 83 dB (in the 2 kHz range)

Second wall - 3 layers 5/8 gypsum each side, otherwise identical - STC 75, TL @ 50 hZ 41 dB, coincidence dip @ 2500 hZ (slightly more peaky than before, otherwise no change you would ever HEAR) , 70 dB TL @ coincidence, (surrounding TL values around 83 dB

Bottom line - stick with all 5/8, you get a bit better LF TL and a lot less hassle trying to remember which thickness goes where... Steve

[sharward]

. . . stick with all 5/8 . . . a lot less hassle trying to remember which thickness goes where...

I couldn't agree more. Think about it: you're going to have a lot of wallboard (hopefully) delivered to your place. If it's all the same stuff, you can work from a single pile of the crap.

That will be very important for me if I'm going to make good on my pledge to allow room for Woman* park in the garage during the construction process (I won't be so lucky!).

*A tribute to our Peterborough bunker builder friend

[Sammy in Aus]

Hi Guys,

Thanks heaps for the info - i think i am finally understanding things more clearly now.

Some more questions though:

1. As i can get MDF (Fiberboard) cheaper then gypsum - i would like to use 18mm (around 5/7 i think). Will this be as good as 2 x sheets of the gypsum?

2. Do you think that this solution if done properly will get me enough TL to keep the nieghbors happy?

3. I will send pictures today or tomorrow to show more detail.

Thanks again guys,

sammy

[Sammy in Aus]

OK - here are some images:

I will add plans/drawings soon also.

[Sammy in Aus]

COUPLE MORE...
[/img]

[Dan Fitzpatrick]

Rough calculations - two identical walls, both with 2x4 stud double frames, 1" apart frame to frame, effective air(insulation) gap of 8" -

First wall - two layers 5/8 gypsum, 1 layer 1/2 gypsum each side - STC 75, TL @ 50 hZ 40 dB, coincidence dip @ 2500 hZ, 70 dB Slightly rounder dip than using all 5/8 - (surrounding TL values around 83 dB (in the 2 kHz range)

Second wall - 3 layers 5/8 gypsum each side, otherwise identical - STC 75, TL @ 50 hZ 41 dB, coincidence dip @ 2500 hZ (slightly more peaky than before, otherwise no change you would ever HEAR) , 70 dB TL @ coincidence, (surrounding TL values around 83 dB

Bottom line - stick with all 5/8, you get a bit better LF TL and a lot less hassle trying to remember which thickness goes where... Steve

hey steve, it seems to me those TL numbers might be a tad optimistic ... i know you said they are ROUGH

IR 761 (pdf link) shows a wall i think is simlar to what you're talking about.

with one layer 5/8 on each leaf, the test showed 15.6 db TL at 50hz (doc page 336/pdf 338)

with two layer 5/8 on each leaf, it showed 26.7 db TL at 50hz (doc page 350/pdf 352)

so it's pretty impressive, that doubling the mass on each side added 11.1hz TL at 50hz.

my question is, does it really seem realistic that adding one more layer on each side brings it up to 41db TL at 50hz. that would be a 14.3 db additional TL

i'm not sure how to judge this, obvioulsy the mass law (double the mass, gain 5-6db) is exceeded for double stud construction ... the 761 data shows that ... so i don't know how to predict what three layers should add ... but i'm skeptical it would add 14.3

it would be great if 3 layers of 5/8 would get you 40db at 50hz, but im not convinced ... from what i've ben able to figure you might need more like 5 layers on each leaf to get that much TL.

what do you think?

dan

[Sammy in Aus]

Hi Guys...

Any thoughts on the previous questions...

1. As i can get MDF (Fiberboard) cheaper then gypsum - i would like to use 18mm (around 5/7 i think). Will this be as good as 2 x sheets of the gypsum?

2. Do you think that this solution if done properly will get me enough TL to keep the nieghbors happy?

Thanks,

Sammy

[knightfly]

Dan, you're right about the optimism; couple of reasons - one, the numbers you get from IR-761 are FSTC and REAL TL, measured with REAL walls, etc - no calculator can figure in the realities of minor booboos done by carpenters, dissimilarities of materials, etc - plus, those were calc'd with the old demo of Insul, which tended to be a bit optimistic even as calculators go.

Main point is, same calculator/same optimism, little calculated diff between using a layer if 1/2 and sticking with all 5/8 - the slight extra mass of using all thicker gypsum buys typically a dB or two at the bottom end, and loses next to nothing at coincidence frequency, where there is already more than adequate isolation.

Sammy - A double thickness of MDF would typically have about the same, possibly slightly higher mass than two single thicknesses of gypsum; however, the joints in a single layer of MDF would be very weak, where a double layer of gyp would have overlapping joints.

But the MAIN problem you're going to have is that freakin' corrugated metal - there is no practical way I'm aware of to keep it from screwing up your 2-leaf system - even a couple of mm of air gap between layers causes some loss of isolation in a wall system, and those probably 20mm "waves" in the metal would really mess up a mass-air-mass system.

For that reason, in order to get any decent isolation for a band you would need to over-build the two centers of mass you add - something like 2 layers of the heavy MDF each side, spaced at least 300mm apart with insulation between would likely give enough isolation to keep neighbors from bitching too much, IF (and ONLY if) it's done tight, sealed up, and a double airlock door used. Much less than that, and you're not likely to come out very well.

If you've looked around much (still haven't updated your profile, BTW) you've likely seen things on ventilation without losing serious isolation (not a piece of cake), door seals, windows, etc - so you know what I'm talking about. I know you're hoping I'll say "oh, just do this and it will be fine", but it really wont if you can't go as heavy and tight as I described. Sorry... Steve

[Sammy in Aus]

Hi Steve,

Thanks for that... you're right I was hoping you woudl say something like that becuase i have wanted this for so long and now that i have somewhere to do it, i am worried that i am still not going to be able to do it.

Anyway - i'm not giving up yet so seeing as the Corrugated Metal is only on the roof - I am thinking that I use the 18mm MDF sheeting stuck directly to the metal snd then the actual internal wall will sit flat below the bottom of the triangular roof truss (so that i have no contact between inner and out layers) which will give me a great deal of gap between the 2 leafs.

The walls i would then treat as previously stated only leaving a minumal gap between frames and using single 18mm layer of MDF.

I understand your point about the joins and not having an overlap. To overcome this - could i use 100mm strips of 18mm MDF secured over the joins instead of full sheets (cost issue)

Thanks again,

Regards,

Sammy

PS - have updated profile.