[Ted White]

You can build a hatch for the ceiling access. PM me if you want a diagram.

 

[Ted White]

You can try an exterior door with weatherstrip. Or two of them such that when closed, they create an airlock.

Decouple the drywall from the joists if possible

 

[Ted White]

I was referring to the ceiling drywall on the joists. Clip + channel would do it.

Walls are fine as-is

 

[Ted White]

Many places sell many clips. To directly answer your question, we do, though I don't want to come across as a commercial.

 

[Ted White]

To be clear, our company is not affiliated with the forum. See the link in my signature. Give us a call if you'd like.

 

[Ted White]

The ceiling clips don't all the way to the wall, but the ceiling drywall does. Right to the studs. THen the wall drywall buts right up to that ceiling drywall. No gap

 

[Ted White]

There's a clip calculator there, but essentially you can take the total sq. ft and divide by 5.

Rows of hat channel are spaced every 24" along ceiling. So you look up and see a row every 2 feet.

Lets take a look at just one row of channel. You'd see that there was a clip every 48" along the length of that one row of hat channel.

So not a lot of contact points, and large increase in the flex of that ceiling. Decoupling brings a whole other level of isolation. Nothing more than R19 is needed, from a practical standpoint. Insulation offers a better payback in terms of performance when installed in a decoupled system.

Same for the mass of the drywall. Double 5/8" rock is more effective if mounted on a spring (clips + channel).

The selection of the correct channel is critical. You'll get this locally, but here's an article that emphasizes the importance of proper channel. http://www.soundproofingcompany.com/library/articles/furring_channel_with_resilient_sound_clips/

 

[Ted White]

If using the proper channel you're good to go. Unless you exceed two sheets of 5/8". Then you have to change the pattern, with rows every 16" instead of 24"

 

[Ted White]

You really, really want the mass. Lot of work to limit the weight to double 1/2". Makes a big difference especially in the low frequencies.

 

[Ted White]

The rubber isn't the significant component in the decoupled clip system. It's the ability of the Drywall Furring Channel to flex without being restrained by screws.

The system you describe will work equally well with or without the rubber pieces you cut, I'm afraid. This tconcept has been looked at a lot over the years, but does little to nothing. This is why you don't see it done.

 

[Ted White]

You are going to pre-drill slots on all the joist attachment points? 2 per joist? That's 304 slots to cut for a 15 x 24 room. You will also have 2x the contact points with these contact points being more conductive.

 

[Ted White]

First of all, I admire your cleverness. It's logical to go down the road you have.

The whole system is made or broken based on on that Hat Channel. It's the weakest point in the drywall suspension. The thought of modifications to it scare me is all.

 

[Ted White]

Screwing the channel to the joists (with or without the rubber you mentioned) is creating a coupled system.

Inserting the channel into the clip array is creating a decoupled system. Much more lossy connection.

In a coupled system, much will be defined by the contact points, their quantity and role in conduction. In a decoupled system, the contacts are less of an issue, and results are determined by the degree of free-flex created by the 25 gauge channel and the essentially non-fastened attachment to the clip.

Clips are not categorized by ceiling clip vs. wall clip. The two piece clips available from many outlets have an advantage in the low frequencies. The Neoprene in the 2-piece clips act to damp the excursion of the components, as well as damp some of the vibration coming from clip components. This is why a two-piece clip tests better than a one piece clip.

There's a lot going on

 

[Ted White]

It's certainly no trouble at all. These are good and common questions. 1 person asks the question that dozens of others are wondering also. It's all very good.

You can follow the link in my signature for more information.

 

[Ted White]

Thanks for the kind words bb.

The most common lawsuits are with Resilient Channel, not clips. Res Channel is notorious at this point. The problem is that there is no standard for the manufacture of this product. No spec at all. So you're left to the whim of a steel bending company. Not the case with Drywall Furring Channel that the clips employ. The Drywall Furring Channel is specified by the Steel Stud Manufacturers Association.

I would recommend not leaving the gap, and keep the joints tight. Seal the second layer

 

[Ted White]

I have to say I see some threads were the Hat Channel seems to be to thin.

...but the guage steel that I see being used scares me to think that 2 layers of drywall will just stay there.:sweat: I am using a heavier guage steel it may not be what recomended as far as flex goes but it gives me piece of mind.

Fortunately, there are governing bodies that very formally test construction materials prior to making recommendations regarding best installation practices. The Steel Stud Manufacturers Association has tested and rated all things steel. Steel Studs, C-channel, etc. The 25 gauge Drywall Furring channel is rated for the load. It's what is spec'd by all clip manufacturers, here and abroad. Been used for a decade.

Going heavier on the furring channel will limit your results as you say. Not recommended at all. Not needed at all. If you feel the need to use 20 ga. channel, I'd skip the work and attach directly to the joists. Call it a day

 

[Ted White]

Your questions and thoughts are good and reasonable. 1 person asks what 20 others are also asking themselves. It's all good.

 

[Ted White]

That's some beefy steel!! That's not 25 gauge. http://www.soundproofingcompany.com/library/articles/furring_channel_with_resilient_sound_clips/