# Double 5/8" Drywall No Insulation?



## PumpkinSpice (Aug 8, 2016)

Hello,

I have a very nice contractor who has been saving me quite a bit in costs and his idea for a wall where I'd like to have some soundproofing is to do double 5/8" drywall with no insulation. I'm just curious if having no insulation will affect the soundproofing? He says no and this is where we are cutting a corner for cost, also this is an interior wall. Any advice is appreciated. 

PS I'm not looking to super soundproof this wall just a little deadening because both sides are common areas and not bedrooms. Thanks! 

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## gordie (Nov 6, 2012)

If you want sound proofing insulate period double 5/8'S is great but inso deadens the drum effect . If your not sure get him to board one side first and do a sound test like knocking and talking one the boarded side then bat a small area do the same you'll here a difference . and it makes a big difference when the whole job is done the


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## keke (Mar 7, 2012)

If you want soundproof and you don't follow regulation is like putting water in a broken bucket


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## thefinisher (Sep 2, 2011)

Still need insulation for best results preferably rock wool. But double 5/8 will work if you put green glue between sheets.


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## MrWillys (Mar 10, 2014)

There are many methods of sound control such as thicker drywall, sound caulking, insulation, resilient channel as well as staggered independent studding. IMHO, staggered studding and or resilient channel are the most effective. See section 3 here:

http://www.lafarge-na.com/GA-600-09.pdf


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## edo_alley_revisited (Aug 8, 2016)

We often use double 5/8" with green glue. sound batt insulation. 5/8" on the other side. Staggered studs are good also.


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## gordie (Nov 6, 2012)

Too much for what this guy needs way too much expense inso double 5/8's for what he wants yes


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## endo_alley_revisited (Aug 9, 2016)

gordie said:


> Too much for what this guy needs way too much expense inso double 5/8's for what he wants yes


Maybe he could take on a night job for some extra cash? Anyhow, why do it at all if it isn't going to improve anything? I certainly wouldn't skip insulation in the walls.


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## Wimpy65 (Dec 17, 2013)

So I'm doing a renovation project that's making apartments in an old building. The ceiling below the apartments is only 1/2" drywall. The plans call for resilient channel and 5/8" Type X to be added to the ceiling. From all that I've read, that is a flawed system. Everything seems to say that you never want a layer of drywall, resilient channel, and then the second layer of drywall. I need to come up with a floor/ceiling assembly that has a 1 hour fire rating and a STC 50 rating. Keep in mind, the is one layer of 1/2" regular drywall on the ceiling already. Any suggestions would be appreciated! :yes:


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## Wimpy65 (Dec 17, 2013)

I'm sure this is a very basic question, but I don't deal with resilient channel very much. How do the carpenters attach the baseboard without canceling out some of the benefit of the channel?


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## thefinisher (Sep 2, 2011)

Wimpy65 said:


> So I'm doing a renovation project that's making apartments in an old building. The ceiling below the apartments is only 1/2" drywall. The plans call for resilient channel and 5/8" Type X to be added to the ceiling. From all that I've read, that is a flawed system. Everything seems to say that you never want a layer of drywall, resilient channel, and then the second layer of drywall. I need to come up with a floor/ceiling assembly that has a 1 hour fire rating and a STC 50 rating. Keep in mind, the is one layer of 1/2" regular drywall on the ceiling already. Any suggestions would be appreciated!


Double 5/8 over the 1/2". Or demo 1/2" and double 5/8".


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## MrWillys (Mar 10, 2014)

Wimpy65 said:


> So I'm doing a renovation project that's making apartments in an old building. The ceiling below the apartments is only 1/2" drywall. The plans call for resilient channel and 5/8" Type X to be added to the ceiling. From all that I've read, that is a flawed system. Everything seems to say that you never want a layer of drywall, resilient channel, and then the second layer of drywall. I need to come up with a floor/ceiling assembly that has a 1 hour fire rating and a STC 50 rating. Keep in mind, the is one layer of 1/2" regular drywall on the ceiling already. Any suggestions would be appreciated! :yes:


Carl,
The Gypsum Association FC-5107 will meet the criteria you're asking about. Page 136

http://www.lafarge-na.com/GA-600-09.pdf

However, this is with the exsisting 1/2" being removed or the Architect of record should sign off on a hybrid assembly.
Scott


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## gordie (Nov 6, 2012)

I can say from experience never run rc channel over existing drywall it causes the oposite effect of what it is used for. TF has the right idea if your not removing the 1/2" .


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## nbriley (Oct 28, 2018)

gordie has the right reasoning, remove the old drywall add hat channel and 2 layers of 5/8, insulate well before adding hat channel but by all means remove old drywall


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