Sound proof with a soffit - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 27 Old 06-11-2009, 01:12 PM - Thread Starter
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Help Anyone! I am sound proofing a hometheater and from everything I read I don't want to be punching holes in the sound proof walls. But my contractor said if they build columns or a soffit they need to nail them through the sound proof dry wall to the room frame. Anyway to avoid this because I assume this will allow sound transmission to the frame and therefore out of the room.
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post #2 of 27 Old 06-11-2009, 01:15 PM
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Nails driven through the drywall won't be a problem. Holes cut through the drywall and left open will.

How do you think the drywall is being held to the wall? Nails and/or screws through it and into the studs behind.

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post #3 of 27 Old 06-11-2009, 02:49 PM - Thread Starter
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The drywall is decoupled by RSICs clips. So they aren't nailed or screwed directly into the frame.
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post #4 of 27 Old 06-11-2009, 02:52 PM
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Nails are never a great idea. Small detail

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post #5 of 27 Old 06-11-2009, 05:37 PM - Thread Starter
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Ted, any advice on what to do?
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post #6 of 27 Old 06-11-2009, 05:58 PM
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Get a different contractor, this one has limited intellectual horsepower and wants to build it like his grandfather taught him.
You can attach a soffit to a decoupled ceiling and wall structure without going into the framing.

Columns? they need minimal wall attachment and as long at they are standing on the floor just a few screws into the drywall (and not further) is going to keep them there. Think of them as a piece of furniture anchored to the wall. You can hide the attachment points at the top and bottom with molding. I actually attached blocking to the ceiling and the floor and screwed through the front of the column. Two screws on top, two on the bottom into the blocking.

If we had a picture of your room and proposed dimensions of the soffit we could get more specific.

If you had pre-planned this out a little more you would have located a hat channel directly where the soffit will mount to the ceiling and wall for additional support but it isn't 100% necessary.
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post #7 of 27 Old 06-11-2009, 06:06 PM
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Certainly more details would be needed to address this. Have you discussed this with the supplier of the materials?

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post #8 of 27 Old 06-11-2009, 06:51 PM - Thread Starter
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Thanks.. unfortunately I can't switch contractors so I just have to educate him as I become educated. I will take some pictures and post them with the dimensions.
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post #9 of 27 Old 06-11-2009, 08:23 PM
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OK here is what you have to tell the contractor. Instead of building a heavy framed soffit that is attached to a the wall and ceiling framing (like he has done all his life) you are going to need to design it as light as possible and attach it to only the drywall and hat channel where possible.

Screws, construction glue and maybe a few toggle bolts are what you are going to be using.
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post #10 of 27 Old 06-11-2009, 08:35 PM
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Quote:
Originally Posted by puzzled View Post

The drywall is decoupled by RSICs clips. So they aren't nailed or screwed directly into the frame.

Apologies, I guess I was envisioning a staggered wall.

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Nails are never a great idea.

Not the best blanket statement to make. There are many instances in home construction where nails are a better option than screws.

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post #11 of 27 Old 06-12-2009, 02:53 PM - Thread Starter
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here are pics of the room ... any advice??
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post #12 of 27 Old 06-14-2009, 09:55 AM
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Quote:
Originally Posted by Suntan View Post

Not the best blanket statement to make. There are many instances in home construction where nails are a better option than screws.

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Could you point out where? The only thing I can think of where I used nails other then screws was a fire rated metal door. The metal door frame was designed to be nailed. Oh, and trim -- trim would be hard to do with screws. Maybe some roofing and other exterior work, too. I also used some nails when building some framing for a door.

Other than these instances, I like screws. My house has incredibly squeaky floors and horrible drywall because of nails. Those problems would be ameliorated or elimated with srews.

Bob
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post #13 of 27 Old 06-14-2009, 10:22 AM
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Your double door will be the weak link in all of this, unless you have have a similar door set to create an airlock when all doors are closed.

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post #14 of 27 Old 06-14-2009, 12:33 PM
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Puzzled, what size soffit did you have in mind?
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post #15 of 27 Old 06-15-2009, 07:56 AM
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Quote:
Originally Posted by ctviggen View Post

Could you point out where?

For the same basic “size” of hardware, the cross sectional area of a nail is larger than a screw. Also, the fluted structure and the process of rolling the screw threads produce significant stress concentration spots on the shank of a screw that nails do not have (unless you are using ring-shank nails.) These two factors make nails much more robust in areas where the fastener is loaded in shear.

Further, nails are allowed to flex and “give” (pull out) when the structure undergoes severe tension loads. Where as the shape and design of a screw (as cited in the previous paragraph) makes them much more likely to fail completely (snap/break) in a similar situation. For example, in a sever event (a tornado say, or a case where way too many drunk college kids significantly overload a deck) the slow/gradual failure (relatively speaking, it may still happen in the span of a second or less) of pulling nails out of joints requires significantly more energy than snapping a screw. The added energy required may well be the difference between a flattened house/deck and one that is just severely damaged. (If you don’t think it is true, nail 10 nails into a board and drive 10 similar sized screws into a board. Now take a pry bar and quickly pull the nails out with your right hand and quickly snap the heads off of the screws with your left, your arms will easily tell you which one had to do a lot more work.)

Lastly, nails are a lot cheaper and faster to install than screws.

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post #16 of 27 Old 06-15-2009, 08:04 AM
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In general, screws are appropriate in a home theater given the unusual stresses the framing will encounter. Generally elements are screwed and glued to survive.

We have to take great care to make sure things stay tight. Hard surfaces need an intervening layer of caulk or adhesive so there's no chance of a rattle.

These noises unfortunately show up months later after things settle.

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post #17 of 27 Old 06-15-2009, 08:11 AM
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I appreciate that Ted. I do have a rather extensive understanding of mechanical fasteners myself. I do not claim to say that nails are better then screws, as it is not universally true.

I was merely pointing out that your original statement was rather pithy to the point of being too general. Like it or not, people will tend to take comments you make as gospel around here and disregard most of the context surrounding it in the rest of the thread.

Saying, Nails are never a great idea can give people the wrong impression.

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post #18 of 27 Old 06-15-2009, 11:44 AM - Thread Starter
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I'm looking at building a 6in to 1 ft. soffit. Just enough to hide indirect lighting and maybe some cans and possibly the rear speakers. And maybe even the projector.
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post #19 of 27 Old 06-15-2009, 12:01 PM - Thread Starter
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Big, btw your theater is sweet! I hope I can get mine to look half of that and I will be happy.
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post #20 of 27 Old 06-15-2009, 02:51 PM
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If you can wait till later this week I will back in my office and can put together a napkin sketch and post it with the details of a soffit that size. You should have your room built prior to adding the soffit for the greatest sound proofing. Then a 2x2 can be mounted to the walls with liquid nails construction adhesive and drywall screws (not into the studs). Then a vertical stub wall can be built with metal framing (because it's lighter) and screwed directly to ceiling drywall. ( it's a good idea to put washers on the screws) If the hat channel for the ceiling is located directly over that location all the better. Then you have all you need to add lights and then drywall. Prior to adding the drywall the soffit should be stuffed with fiberglass insulation. I would use drywall adhesive in addition to the drywall screws.

There are other ways this is just one. You are correct to be concerned that the contractor might short circuit your isolated structure and unless you are on site supervising they just might. It is likely that the person who you discuss how things are to be done and agrees to the design will not be the person actually doing the work that day and they will revert to how they know how to build a soffit.

This is why so many of us have preferred to DIY.
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post #21 of 27 Old 06-17-2009, 09:43 PM - Thread Starter
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Big, looking forward to the sketch. Any ideas on sound proofing the split level ac I will be putting in.
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post #22 of 27 Old 06-18-2009, 07:33 AM
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Then a 2x2 can be mounted to the walls with liquid nails construction adhesive and drywall screws (not into the studs).

I am about to mount my soffit to my drywalled theater. I have staggered studs and 2 layers of 5/8 with gg. I had planned on screwing 2x2s to the studs on the walls. Should I not do this?

I had also planed on screwing the top plate of the soffit into my hat channel on the ceiling on the perpendicular runs, and using toggle bolts on the runs where I had not channels.
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post #23 of 27 Old 06-18-2009, 07:38 AM
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Quote:
Originally Posted by puzzled View Post

Big, looking forward to the sketch. Any ideas on sound proofing the split level ac I will be putting in.

OK, sketch


1)Go around the perimeter of the room and glue (construction adhesive) and screw a 2x2 to the wall using 2 1/2 inch drywall screws.

2) Using a chop saw and a metal cutting blade cut a zillion pieces of metal framing the height of the soffit.

3) Screw uprights into the top rail then attach the assembly to the ceiling using drywall screws, I like to use washers on the screws to make the attachment point more secure. Use at least a screw every ft or closer.

4) Screw on the bottom rail. If the soffit is tall enough you can add before securing the assembly to ceiling but if it is going to get in the way of adding all the drywall screws leave it off.

5) You can add a few spacers between the 2x2 on the wall and the metal bottom rail but it is only to hold the metal assembly straight.

6) add lights and run any wiring

7) Stuff with insulation

8) Add the drywall with drywall to metal frame adhesive and drywall screws.

If you are going to put up cornice molding I would add 1/2 inch plywood to the face of the soffit before the drywall so that the molding will attach better.
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post #24 of 27 Old 06-18-2009, 07:40 AM
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Quote:
Originally Posted by puzzled View Post

Any ideas on sound proofing the split level ac I will be putting in.

is this a mini split or forced air system for both the basement and the first floor.
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post #25 of 27 Old 06-18-2009, 07:43 AM
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Take a look at my thread. I decopled my soffits using a technique from Ted and John Hile. I only have 1 coupled surface at the wall. I should have some decent pictures of the soffits going in.

Eric

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post #26 of 27 Old 06-18-2009, 07:48 AM
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Quote:
Originally Posted by sotwell View Post

I am about to mount my soffit to my drywalled theater. I have staggered studs and 2 layers of 5/8 with gg. I had planned on screwing 2x2s to the studs on the walls. Should I not do this?

you will be fine the OP was using clips and channel on the walls not staggered studs.
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post #27 of 27 Old 06-22-2009, 12:22 PM - Thread Starter
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Sorry Big, I'm kind of lost. I don't know much about construction so I am not sure I understand the instructions or the drawing. Do you glue the 2x2s at the floor or at the height of the soffit. where to the metal zillion pieces cut go are they the height going vertically. sorry. I need a little bit more detail in order to understand and convey to my contractor. I'm still trying to find out about the a/c. As far as I understand it I will be securing it to the sound proof drywall, but somebody told me I can also secure it to the rsics clips or the hat track, but if the dry wall is up already how do you find the clips or the hat track????
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