R/E/P Community

R/E/P => R/E/P Archives => Acoustics in Motion => Topic started by: jetbase on February 17, 2009, 05:46:14 pm

Title: Factory roof isolation
Post by: jetbase on February 17, 2009, 05:46:14 pm
I have a factory roof I need to get some isolation from & am trying to work out the best way to do this without losing too much height.

The roof consists of corrugated asbestos, sarking, steel mesh (to support the sarking I guess), steel girders & then the timber frame for the ceiling attached to the girders, as per the photo below.

There are two options I'm considering:
1. Stuff the cavity with insulation, then hang a plasterboard ceiling using RC2.
I'm concerned there may not be enough isolation with this option since, of the two leaves in this structure, one would only be thin asbestos.

2. Put a layer of plasterboard up first, behind the timber, then stuff with insulation & then hang the ceiling with RC2.
With this option I'm worried that the extra layer of plasterboard will act as a third leaf (or that the asbestos will) & have a negative effect.
Unfortunately I can't attach the plasterboard directly to the existing roof material to make it a single leaf.


What are your opinions? Are there other options to consider?
Basically I'm just looking for the best isolation I can get without having to lose much height in the room or remove any of the existing roof structure.

Thanks,
Glenn

index.php/fa/11312/0/
Title: Re: Factory roof isolation
Post by: Thomas Jouanjean on February 18, 2009, 11:32:06 am
Asbestos...  Confused

Get out of there!
Title: Re: Factory roof isolation
Post by: jetbase on February 18, 2009, 06:04:03 pm
Thomas Jouanjean wrote on Thu, 19 February 2009 03:32

Asbestos...  Confused

Get out of there!


Yeah, what a disasterous product! These days, around here, rather than remove such large quantities of asbestos from factory roofs they just spray it with some kind of sealant & keep it in place.
Title: Re: Factory roof isolation
Post by: franman on February 22, 2009, 12:41:50 pm
If I read this correctly, option #2 would offer a better isolation system, as there would be two sets of boundaries and a damped air space. Option #1 as you noted, will really only create on boundary with any significant mass BUT it would be a significant improvement over what you have.

The problem I see is how practical is it to mount the drywall behind the existing wood framing?? if this can be done without getting into hazardous work near the asbestos (and yes it will all be hazardous) and if the drywall can be properly sealed, then it's a better system.

Looks like the wood framing is around 6" (15cm).... right??
Title: Re: Factory roof isolation
Post by: jetbase on February 22, 2009, 08:03:27 pm
Hi Fran,

Your advice matches that of another acoustician who contacted me off list (thanks Mark). I should be able to do option #2, fully sealed, without disturbing the asbestos at all.

The wood framing is 4x2". I'm actually now wondering about the possibility of pulling off the timber framing & re-orienting it 90 degrees so that I can stagger it & keep it totally separate from the steel girders. I won't know how feasable this is until I remove all of the existing ceiling material.

Btw, this is the same room that I previously asked advice about for the floor in this thread:
http://recforums.prosoundweb.com/index.php/m/365342/6028/?sr ch=mezzanine#msg_365342

I'm still formulating an overall design for the studio in between tearing down my current studio (& discovering that hammer should never meet shin) & setting up a temporary CR for mixing.

Cheers,
Glenn
Title: Re: Factory roof isolation
Post by: Thomas Jouanjean on February 23, 2009, 03:21:01 am
Maybe using 2x OSB instead of gypsum to seal (n
Title: Re: Factory roof isolation
Post by: jetbase on February 23, 2009, 09:29:25 pm
Are you suggesting the using the OSB on inner or outer leaf (or either)?
Title: Re: Factory roof isolation
Post by: franman on February 23, 2009, 10:25:53 pm
If you use OSB or Plywood as the inner layer on the inner side you will have a sound point of attachment for subsequent ceiling finishes, etc. This is something we regularly do.

Also, the advantage that Thomas lists are valid... using differential materials on adjacent layers will tend to make a new composite 'material' that is stronger than the sum of it's parts... this is good acoustic construction practice.

Cool

FM