# Insulating



## Windows on Wash (Aug 30, 2011)

Keep researching.

Insulation will net you very little in terms of sound attenuation vs. and open cavity.

You can get a much more sound proof ceiling with only the loss of a few inches if you had it from resilient channel on isolators.


----------



## wkearney99 (Apr 8, 2009)

Sound insulation between the joists will help cut down on voices carrying between the levels. But it will not help reduce bass noise (music/tv) or walking sounds above. For that you'd need to use the isolation channels. Those work by de-coupling the surfaces. It's the hard connections between the layers that transfers the lower frequencies. 

Using thin drywall is almost worse than using none. That and fire code probably requires at least 1/2". 

But is it even legal in your area to rent out a space with such low ceilings?


----------



## Gary in WA (Mar 11, 2009)

I agree with the last post, (sorry WOW) cavity insulation will give 4-5 more points in STC ratings; http://www.stcratings.com/assemblies.html#01

Resilient channel is much better, as said; http://www.certainteed.com/resources/Guide for Residential Sound Control.pdf

Gary


----------



## Nailbags (Feb 1, 2012)

Sound engineers will tell you that the sound does not travel through the cavity it travels through the 2x's yes the studs the joists that is were the sound travels threw. Insulation has very little effect on sound. Yes it may deaden the sound but all in all use Gary's advice. Or use a double layer of 5/8ths sheetrock.


----------



## Windows on Wash (Aug 30, 2011)

Gary in WA said:


> I agree with the last post, (sorry WOW) cavity insulation will give 4-5 more points in STC ratings; http://www.stcratings.com/assemblies.html#01
> 
> Resilient channel is much better, as said; http://www.certainteed.com/resources/Guide for Residential Sound Control.pdf
> 
> Gary



No need to be sorry Gary (especially for being wrong...:whistling2 :laughing:

The figure you quote shows a metal framed wall offset between hollow and filled.

Note: I am not suggesting that the poster not fill the cavities, just that it will not likely provide him/her with the performance that he/she is looking for.

Metal framing (obviously not what we are dealing with here) is much better about not transferring the sound as compared to solid wood framing.

If you look at the difference between a 2x4 stick framed wall with and without insulation, the difference is more like 3 STC points. That will not be noticeable to the average human ear.

http://www.guardianbp.com/litlib/naima_bi405.pdf

Ted White is the guru on sound on this board and he recommends insulation along with other methods...and that was my point.

http://www.diychatroom.com/f103/sound-proofing-room-173494/

Resilient channel, double drywall, or other mass and decoupling techniques are going to be the big changers.

http://www.nationalgypsum.com/resources/selector/FloorWoodFraming.pdf


----------



## ngordonmd (Aug 24, 2013)

Thank you for the replies. I know that resilient channels are the best solution, however I just dont have the space. The ceilings are currently 6'6" which is barely livable. I may try to lower the basement in a few years to get more height at which time I will install resilient channels and double layer 5/8 sheetrock. However at this time I have almost no height to spare. So what I was really looking for is whether there were any small things i could do to help the sound transmission. I am going to use roxul between the joists as I have read several very good reviews about the product. I know its not going to net me too much gain over regular fiber glass, buts its worth a try. My other thought was to use 2 layers of 1/4" sheetrock with green glue in between. Any thoughts on that idea? Thanks.


----------



## ngordonmd (Aug 24, 2013)

I also came across this product

http://www.acousticalsurfaces.com/rsic_clips/rsic-1-low-profile.html?d=46

Any thoughts?


----------



## wkearney99 (Apr 8, 2009)

Certainly looks like a clever way to bring the channel up a bit. But you could also do this with a section of lumber put between the joists. The L bracket just makes it a one-step process to attach to the inside of the joist, vs cutting and nailing something else up on both sides. Which you might not have if there's other infrastructure in the way. 

But have you confirmed that it's even legal to rent out a space with such low ceiling height? It wouldn't make much sense to alter the space in this manner only to discover it cannot legally be rented out with such a low clearance. That the previous owners claimed it was rentable doesn't necessarily make it so. That and remodeling brings along modern code requirements. Get this wrong and you can end up in a world of hassles, especially when dealing with tenants and their usual issues...


----------



## ngordonmd (Aug 24, 2013)

Luckily the unit was grandfathered in by the city years ago so has its own address and its own electrical box. I have actually already gone through part of the inspection and they have signed off on all the framing, plumbing and electrical. They made a note of preexisting 6'6" ceilings and gave them the ok. I think I will save my money and go with R19 insulation and use it to put in the resilient channels. Any other suggestions or tips would be welcome. Thanks.


----------



## wkearney99 (Apr 8, 2009)

Indeed, lucky to have that carry forward! The channels on those L-brackets and R-19 is probably going to be a good solution.


----------



## ngordonmd (Aug 24, 2013)

Anyone have any thoughts on doing 2 layers of 1/4" sheetrock with green glue in between as apposed to one layer of 5/8"?


----------



## Deseloth (Feb 10, 2013)

You could use Quietroc instead of drywall.


----------



## wkearney99 (Apr 8, 2009)

ngordonmd said:


> Anyone have any thoughts on doing 2 layers of 1/4" sheetrock with green glue in between as apposed to one layer of 5/8"?


1/4" is not good for ceilings. It just doesn't have enough strength to provide an evenly supported surface. It'd be a real hassle getting it right. It'd end up looking wavy. That and since it's low you'd be asking for someone's head to crack it. Better to use a thicker material. I've not used the pre-made soundproofing boards but in your situation they'd probably be a better solution.

But I have to step back and ask, just how much point is there to soundproofing such a low space? Do you intend to be living in the space above it? That'd be about the only reason I could see for spending so much more to mitigate sound issues. If both levels are going to be renters then, R-19 insulation and regular 1/2" drywall on those channels would seem sufficient. Maybe 5/8" drywall just for added mass. Because going with two layers of 1/2" and green glue, along with the channels, really starts biting into the available headroom (and your wallet).


----------



## ngordonmd (Aug 24, 2013)

I have looked into Quitroc and it ends up being cheaper to just hang 2 sheets of drywall with Green Glue. I'm actually planning on living in the bottom unit and renting out the top, which is why sound proofing is so important. I think maybe I will stick with just the resilient channels and see how it goes. If I want to add another layer of sheetrock later I can.


----------



## wkearney99 (Apr 8, 2009)

Yeah, but two channels of 1/4" is unlikely to be durable enough. If you use the channels then using 5/8" would likely be better. You need the ceiling to be durable. The added mass of the 5/8", the acoustic insulation (don't just use generic pink insulation) and the channels is really a good combination. Going with a sandwich of 1/4" and glue isn't going to give you significantly better sound isolation but would probably end up being worse looking and less durable.


----------



## Windows on Wash (Aug 30, 2011)

As mentioned earlier, I would sister up some lumber that had some sort of sound isolation between it and the original joists and then screw my drywall to that.

I think that is probably your best and most secure solution without sacrificing ceiling.


----------



## wkearney99 (Apr 8, 2009)

Windows on Wash said:


> As mentioned earlier, I would sister up some lumber that had some sort of sound isolation between it and the original joists and then screw my drywall to that.


The trouble with this idea is most sound isolators work better when they don't have any sideways pressure on them. You want your ceiling isolators to hang their weight vertically not horizontally. This way the flexible compound isn't being compressed by gravity. Using the L-brackets and channels recessed into the joist cavity is a pretty brilliant way to do just that. Especially if the channels can be laid to run with the direction of the joists. If you have to run across them then you'd losing the height of the channel and a small gap, but with the joists then you really only need the gap. But this also assumes the underside of all the joists is even and level, if it's not then you'd have to find the lowest point and set all of the channels to it.

I suppose you could cobble up a solution that used some lumber to replace the L-bracket. But then you'd have the problem of that weight decreasing the effectiveness of the isolator.


----------

