Train rumble coming through concrete floor

[nicholasdover]

So I've just built a nice big room in an old factory/warehouse - ground floor, concrete slab, RWR floating walls and ceiling (except support in middle) - and the main sound which I still seem to have had little impact on protecting myself from is the train tracks about 50m away. The low frequencies must be passing into my floor and the room is 7.5 x 5.5 x 3.5m so lots of floor area to hear/feel. Bass in that room is still being worked on - there's too much low end, drums sound way heftier below 100Hz in monitors than in headphones, although decay times are under control now with broadband absorbers around walls, and two corners have tall bass traps. I guess if the low end gets tamed more in general, the trains won't excite the room so much? I've put 2 thick 4x3m rugs down to stop flutter echoes floor to ceiling and hung a ceiling cloud in middle. The train noise is just a bit depressing after all this time, effort and money so any advice would be welcome. Even if it is expensive advice like "you need to build a floor out of x,y and z", at least I'd know. Or "you'll never escape train rumble"...

[A.David.MacKinnon]

No specific help to offer but I'm guessing the answer will be floating the floor and may involve sand and/or neoprene pucks between the floating floor and the slab. I'll stand back and let the real experts answer though.

[MoreSpaceEcho]

unfortunately you would need to float a new floor, AND all your newly constructed interior walls/ceiling would need to be on that floated floor.

floating a floor PROPERLY is serious business, i can give you links if you like.

so the bad news is i think my advice is "you'll never escape train rumble".

the good news is ground floor concrete slab in an old warehouse building is otherwise the ideal spot for a studio. you can make it work. wavelab studio in tucson is/was near train tracks, and plenty of good records came out of there.

[Drone]

Get a timetable

[Nick Sevilla]

Yep,
You would need to build a floating floor.
Auralex makes these wonderful "UBoats" that hold the 2x6 frame off the concrete. After that it is a regular floor.

And to do it properly, you'd need to make it NOT touch the already existing walls. No need to float them as well, if it is too expensive.

The issue will be then, whether or not the trains go through the entire building structure, or mainly it is vibration coming through the floor.

To know this you just need to have a local expert go and listen and take a few measurements.

Do the walls vibrate? If they do they need to be completely redone. A floating floor will not change the walls at all. It will only stop vibrations coming through the floor from getting into your mic stands and equipment. The floating floor will do nothing for airborne noise at all.

Good luck, keep us posted.

[nicholasdover]

Thanks for the replies guys.
So yes, I am making a timetable! I have times and a severity rating "1142 - heavy freight, no ballads 1247 - light rumble, rock through it"

So I think I may have made a breakthrough/change - your posts made me really get my ear to floors and walls as trains came by and I now believe the train rumble is being almost amplified by a couple of resonant sections of plasterboarding, not the floor. I did double layers on walls with offset seams and used dabs of AC50 acoustic caulk between layers to go for a constrained layer damping effect (massive room meant Green Glue too much money for me). I worry I may have missed damping out on a couple of boards! There's a definite bass drum-skin response when I thump in a couple of areas. I'll either have to bond another heavy layer to the face - electrics and decorating are done so not really possible to redo them...

So depressing when you move in, try to get started and realise you messed something up!

[nicholasdover]

To dampen the existing double plasterboard, what could I do? First ideas are:

(1) Green Glue an extra layer of plasterboard to the face to get more constrained layer damping going on.
(2) some kind of mass loaded vinyl assembly? Would that be better at absorbing 40-50Hz?
(3) Is there a clever way of surgically inserting rubber isolators withing taking the wall down?! Like underpinning old buildings....?

Thanks guys

Nick

[vvv]

I really don't know nuffin', but I'd look into shooting mebbe some foam into the walls?

[MoreSpaceEcho]

i think mlv would work BETWEEN layers of drywall, but that'd mean you'd have to remove a layer, and you're not gonna do that. it would also be really expensive to do a whole room like that.

so i would probably go with option 1, and probably skip the green glue.

[nicholasdover]

I have leftover plasterboard from the build enough to stick another layer up, and there's stuff called Everbuild AC50 which is a bit like Green Glue in that it never sets solid - stays like chewing gum under a school desk - which is way cheaper: £4.50 for 900ml as opposed to £14 for GG. It seems like it must do a similar job? Of course if GG promised to be the difference between train noise and silence, I'd pay! I just feel like it won't be...
I've never used MLV and have read of various installation methods - does it need room to wobble by way of absorption? so a tight sandwich between drywall layers won't wobble but does it still serve a purpose there?