# Advice for HT room soundproofing please



## Ranyart (Feb 19, 2008)

Hello fellow HTS members. I am new here but have been a member and reading for quite a while. 

I started to plan to arrange my garage for home theater room. The garage is 165in wide, 248in long and 98in high. The walls are built of, starting from inside, 0.5in cement plaster, 9.5inch aerated autoclaved concrete blocks, 2.5inch styrofoam insulation and 5inch clinker bricks. The floor is 2inch floating anhydrite screed on high density styrofoam insulation. 

The ceiling will be constructed of 2x0.5in drywall and 1x0.5in OSB on metal studs with acoustic isolation clips screwed to wood ceiling joints and 10in of glass fiber insulation in cavity. GG is not decided yet as individual import is horribly expensive and I can’t find European reseller with reasonable offer. 

My major concern is if I need to make additional soundproofing on the walls. They’re pretty thick and heavy (traditional north European construction standards) to acoustically isolate enough, in my opinion. An extra 2xdrywall with studs and 2in of insulation inside will take 4in on each wall, and that I can hardly consent. Please advice. Thanks.


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## bpape (Sep 14, 2006)

The walls themselves will likely do a decent job. Another layer can only help. That said, the extremely rigid existing walls would cause more of a concern in terms of not giving ANY help at all with interior decay time. Even if you did 2" and 2" it would still be very lively but at least it would flex a little instead of being so rigid.

Understood though on the space being a concern.

Bryan


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## Ranyart (Feb 19, 2008)

Thank you Bryan. Obviously all walls will be treated with:


 2" Isover Multimax (OC703 equivalent) glass fiber wool top to bottom on front wall and 5' from front wall
 1" on the rest of sidewalls floor to 5’ high with 0.4” acoustic felt above
 2" of paper facing Isover Multimax on back wall
 chunk style bass corner absorbers floor to ceiling, made of high density glass fiber (Isover PT-80).
Will it help enough with interior decay time or should I treat the room some more ?

At the moment I have no clue on ceiling treatment. My initial plan was to build star ceiling, but its combination with acoustical treatment seem to be tough to combine. Still looking for a solution in HTS threads.


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## bpape (Sep 14, 2006)

Skip the upper rear portion of the side walls. Plan on 4-6" with facing on the rear wall.


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## Ranyart (Feb 19, 2008)

If I skip star ceiling project, will 1" of OC703 on the ceiling be of sufficient treatment ?

I demolished existing non insulated drywall ceiling today in order to build it again with 10" of glass fiber wool in cavity for acoustical and thermal insulation. 

Thinking of starting my own HT construction thread in near future :scratchchin: And by the way, I use ladded, so no Polish jokes please. :bigsmile:


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## Ted White (May 4, 2009)

Are you planning for ventilation? A common sound escape route. 

Decoupled ceiling sounds good. Depending on the isolation you're looking for, you could increase one or more of the ceiling panels to 5/8" for more mass. Adjust clip pattern accordingly.


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## Ranyart (Feb 19, 2008)

Thanks Ted. Since garage is a standalone construction I have to make separate heating and ventilation system. I plan to install small HRV unit with sound absorption ducts. As for ceiling, I will use 2x0.5" Fermacell gypsum-fiber boards that are +30% heavier than ordinary drywall.


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## Ted White (May 4, 2009)

Fermacell sounds interesting! What is a "sound absorption duct?" You mean flex duct with a bit of insulation around it?


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## Ranyart (Feb 19, 2008)

Precisely. A flex duct with an insulation around.


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## Ted White (May 4, 2009)

Great. Keep in mind that while this is a good material to use, it will not prevent sound from passing through the vent hole (as in the ceiling) and out into the surrounding framing.Sound will not follow the path of that flex.


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