Ceiling to keep my neighbours happy

Shot · Post by **Shot** » Mon Nov 24, 2003 12:22 pm

Hi everybody!
Since this is my first post here, I'll take time to say that this is great what y'all doing, taking time and efford to help each other. I've been lurking this forum for a past few weeks, and all I can say that you guys are amazing! You ROCK!! (rock wool or rock'n'roll, however you want it...hehe)

Well, here's the situation I'm in...
I've just rented with a partner a small basement (44 m2) here in Zagreb (that's Croatia... former Yugoslavia... you know... mid-eastern europe). I plan to build a studio. The location is great (center of town) and the rent is great considering size... lot of good factors but we have to deal with a small problem... neighbours!

We have to insulate ceiling to some extent to avoid unhappy neighbours banging on our doors. This building we're in is old-type, built in 1911 with thick thick wall (and I really mean thick - 64 cm thick brick wall), and entire basement has been redecorated few years ago with gypsum board ceilings. We still didn't take off the mounted lamps off the ceiling to check what is the depth from building's ceiling to gypsum board ceiling and if it's filled with anything or it's just air in between. But on a first impression, I think that this gypsum boards were done very well. They seem airtight in connection with walls (except we'll have to handle few holes I mentioned above - with lighting). I definitely want to keep them since we're on a tight budget.
This gypsum ceiling will provide some insulation, but we'll most probably have to build additional ceiling to add more STC. The problem is that the height from the floor to this gypsum ceiling is rather low (2.45 m), so I'm not sure what to do! I was thinking 10 cm thick Helmholtz with mineral fiber tuned to frequencies as low possible. What dou you think? Will that work?
I want to be able to record drums and bass instruments and still keep neighbours off my neck.

I know it's not a perfect situation but I'll have to deal with it.
And also, please excuse my bad english. I'm trying to explain as precise I can, but...hm...

Also, since I live in this f**ked up cuntry, I don't have access to some brand name acoustic materials so I'll have to use standard coustruction stuff found in typical hardware store.

Tough situation... uff...
Please folks... advice me!

knightfly · Post by **knightfly** » Mon Nov 24, 2003 1:37 pm

Shot, unfortunately what you suggest about the Helmholz will actually WORSEN the isolation between you and upstairs. Reason for this is that this will create an extra mass and an extra air space wherever you put this trap, which will weaken the isolation in that spot.

If you've been lurking a while, you've probably come across this thread in the "sticky's" -

http://johnlsayers.com/phpBB2/viewtopic.php?t=598

Ive outlined the basic principles of sound proofing there, and those apply to ANY sound barrier, not just walls.

In order to sound proof your ceiling effectively, you first need to know what is already there, and exactly how it's constructed. Then, you need to make it conform to the basic plan, which is two centers of mass separated by air or insulation or both.

If there is quite a bit of space between the gypsum ceiling and the true ceiling, it's possible you could raise your gypsum ceiling and still improve your isolation. For one thing, those "little holes" aren't little when it comes to sound escaping. It doesn't work ANYTHING like HEAT insulation - the tiniest little crack is a near disaster for sound, where heat will hardly know it's there. Heat works on mainly convection and direct radiation, but sound works mainly on PRESSURE. That's why a tiny crack or hole makes so much difference.

The good news is that standard types of building materials can be used very effectively for sound control. Before I can help much, though, I need to know what the UPPER ceiling is made of, how thick, ANY detail that will help me figure out what you actually HAVE and what would work best for your situation.

What I need from you - A better idea of existing construction. Maybe you can measure in another part of the building to figure out how high the other ceiling is, so we can know the depth of the air space between the two? What is the upper floor - is it concrete, wood, steel with concrete over it, ??? Maybe the owner or superintendent of the building can provide some information?

What types of building materials can you get? Specifically, gypsum wallboard gets used a lot - but I recently found out that it is about 5 TIMES as expensive in the UK as in the US, so I don't assume it's cheap elsewhere any more. Are there companies there that do "blown in cellulose" insulation? This is done by cutting small holes in a wall or ceiling, then using a special machine that blows cellulose fibers into the cavities through the holes, then patching the holes. This alone can improve isolation by anywhere from 6 to 10 dB.

Can you get different thicknesses of gypsum wallboard, such as 9mm, 12mm, 16mm? If so, putting two different thicknesses up over the existing ceiling can make several dB of difference. Ideally, you would REMOVE the existing ceiling and build a RESILIENT framework of some kind and then put up multiple layers of wallboard - but if you're on a tight budget, and you don't need TOO much more isolation, the extra layers will help.

That brings me to the next question - do you have a Sound Level Meter - if so, you should talk to your upstairs neighbors and arrange to do some tests to see just how much more isolation you NEED - you could turn up your sound system til it's where you want it (usually around 85 dB for mixing, but recording live instruments is much louder (drums especially)

Then, measure the sound level upstairs in your neighbor's space and have your partner turn your system down until it's OK upstairs (telephone communication while doing this) then re-measure the level downstairs, subtract the NEW downstairs dB level from the LOUDER, previous downstairs dB level, and the difference is how many more dB of isolation you need.

All this is necessary to get where you want to go, because you can't do a job until you know what that job IS.

Re-read this, make sure you answer all the questions as thoroughly as possible, and let's see what we can do... Steve

Shot · Post by **Shot** » Wed Nov 26, 2003 12:18 pm

ok... I got it...no helmholtz on ceiling...
I took some time to read your faq, some other websites and Everest's M.H.Acoustics... i got it...

It'll take few days for me to check what's the depth in between building's ceiling and this drywall ceiling since I accepted a work offer that needs to be done till weekend (music for commercials), so I wont have time to spend in my soon-to-be-studio.

From what I recall, building's ceiling is around 40-60 cm thick, and I think that it's wood-concrete combination. I'll have to re-check and speak with some neighbours. They'll probably provide me with more detail.

I'll get back to you ASAP, just wait 'till I do this commercials job.

And also... I have access to sound level meter... my friend has it at home and he doesn't know what to do with it... I'll definitely borrow it form him to do some testing.

knightfly · Post by **knightfly** » Wed Nov 26, 2003 2:18 pm

That's fine, I'll wait to hear back from you... Steve