Where do I Install Gaskets, and Drywall?

[ENIGMACODE]

Hello Home Studio Builders

I'm building a rehearsal room - my main concerns are absorption and isolation of sound (it's a free standing room built within my garage) There are NO contacting surfaces between the two rooms. The inside rehearsal room is completely free standing except for the concrete on the floor below the wooden subfloor. As I've read many of the posts here, I'd like to confirm a few things and cut to the quick in regard to the proper installation of gasket material and drywall:

Bottom wall plates (of the wall structure), should be fastened directly to the subfloor perhaps with some construction glue (with no gasket in between) Correct?

BUT

Gasket Material (should) be installed along the top of the wall plate where the cieling joists are fastened - Correct?

Drywall questions:
When installing drywall, should the drywall cover the 1/8" or 1/4" gap at the top of the wall where the gasket is?
OR should you actually leave a 1/8" or 1/4" space and apply no tape or joint compound leaving the gap exposed?

AND

It's my understanding that caulking SHOULD be applied all along the floor where the floor and walls meet BEFORE you apply drywall
Correct?

Thanx for your help
Best Regards
Michael Fraticelli
rocknroll@ucwphilly.rr.com

 

[Michael Jones]

I don't understand a lot of your questions.
Let me start by saying that ANY construction you do needs to be in compliance with your local building codes.

I cannot imagine a single instance where a stud wall would be adhered to a floor using glue.
Bottom plates are secured to the STRUCTURAL floor or slab using anchor bolts or concrete nails.
(Anchor bolts for load bearing exterior walls, and concrete nails for interior non-load bearing walls.)
If its an exterior wall the bottom plate MUST be pressure treated wood.

I think you're just asking for trouble by trying to put a "gasket" along the top plate.

"Gaskets" as you call them, typically go along the BOTTOM plates of exterior walls.
But you can put them along the bottom plates of interior walls too.

A 1/8" - 1/4" gap on drywall?
You haven't worked with drywall much have you?
Those kind of dimensional tolerances are just unheard of with drywall.

Caulk along the bottom plate where it meets the slab?
Yes.

 

[Jeff_D]

just to clarify one thing- any wood in contact with conrete needs to be preasure treated. Non treated lumber in contact woth concrete will rot realtivly quickly

Maybe you could do a few quick sketches so you can better idea of exaclty what your concerns are. Pencil and paper and scan em in or draw it with paint or something or AutoCAD would be nice

 

[Rod Gervais]

Michael,

Here you go - step by step:

Bottom wall plates (of the wall structure), should be fastened directly to the subfloor perhaps with some construction glue (with no gasket in between) Correct?

You do not need construction adhesive between the bottom plate and the floor. The seal at this location will be handled later during construction.

Gasket Material (should) be installed along the top of the wall plate where the ceiling joists are fastened - Correct?

You don't need this if you really have totally seperate construction. A true room within a room has it's own ceiling joist - and (seeing as this is not connected to the structure outside) you gain nothing by this.

When installing drywall, should the drywall cover the 1/8" or 1/4" gap at the top of the wall where the gasket is?
OR should you actually leave a 1/8" or 1/4" space and apply no tape or joint compound leaving the gap exposed?

Drywall shoud be installed as follows:

Install the 1st ceiling layer...... leave this 1/4 to 3/8" from the wall framing. Caulk this joint.

Install 1st wall layer...... leave this 1/4" to 3/8" from the wall/ floor/ ceiling - caulk this joint...... repeat this for the remaining 3 walls......

Apply a 1st coat of joint compound and tape to all joints except corners (those have the caulk)

Repeat the above........ just make certain that at the corner joints you are going to tape that the caulk is slightly recessed in the corners.

When you apply the 2nd (and subsequent layers if you're using more than 2) make certain to stagger the joints in the drywall so that you never have a joint directly over another joint below. Work for a minimum of a 10" lap for all seam locations.

This is the best possible isolation assembly you can acheive with wall construction.

It's my understanding that caulking SHOULD be applied all along the floor where the floor and walls meet BEFORE you apply drywall
Correct?

Nope......... do exactly what I've outline above.

Rod

 

[ENIGMACODE]

Thank you - let me clarify a few things ......

First off - thank you very much for your responses .....

Unfortunately a lot gets lost here in regard to what the knowledge level of the person making the inquiry is .....

I am a BOCA cerified Building, and Electrical inspector for the City of Philadelphia - been in the field for 28 years. In fact I attended siminars in regard to the Rhode Island Club Fire a few years ago which took almost 100 lives. But I'm not an acoustical engineer.

That being said, and having read quite a bit here, I thought I'd try to NON-COMPLICATE my specific questions ....

Can you guys please help me ZONE in a just a few simple questions? Please?


Now bear in mind this is NOT a SUPER Professional Recording Studio......

It's simply REHEARSAL room and my goal is to (cheaply) isolate and absorb as sound as possible from getting to the outside world ...

OK - Now the 3/4" wood subfloor is fastened with coated screws, and GLUED to Pressure Treated 2x6's on concrete and is 'SOLID'

I was under the impression that 'GENERALLY' this room should be isolated as much as possible from the existing walls in my garage .... so yes it's a room within a room 'FREESTANDING'

My questions again regard the need for 'GASKETS'
TYPICALLY WHERE DO I PUT THEM?
I thought they needed to go on the top where the cieling joists lay??????

Now I'm told that they typically go between the bottom wall plate and the wood subfloor? Is this correct?

AND

In regard to drywall, from the last repsonse I take it, that drywall should be installed 'GENERALLY' as you would a conventional room - TAPE ALL JOINTS ALONG THE TOP ETC. - YES? No gaps where gaskets my be between joints - true?

Best Regards
Michael Fraticelli
rocknroll@ucwphilly.rr.com

 

[ENIGMACODE]

Just getting caught up here - sorry

Rod Gervais -THANK YOU ....

Ok - lemme address your last response (and others)

You mentioned:
"You don't need this if you really have totally seperate construction. A true room within a room has it's own ceiling joist - and (seeing as this is not connected to the structure outside) you gain nothing by this."

So then NO gaskets are neccessary (floor plate or top plate)
Just go ahead and assemble the room conventionally with coated screws - but if I want to add a little glue between the plates - no accoustical harm done - and I may add a little strength by doing so?

You mentioned:
"Drywall shoud be installed as follows-Apply a 1st coat of joint compound and tape to all joints except corners (those have the caulk)"

"Repeat the above........ just make certain that at the corner joints you are going to tape that the caulk is slightly recessed in the corners."

Rod
Unfortunately I can't afford the labor, room, or expense of applying more than ONE layer of drywall .....
Soooo - should I caulk or tape the corner joints?

Should I caulk the corners on the floor (where the walls meet the floor?)

*I FORGOT TO MENTION EARLIER:
I'm naturally going to have to treat the entire inside room accoustically with Auralex Panels on the cieling, Bass Traps if necceessary, and was thinking of covering about 60% of the walls with R11 3 1/2" unfaced AND
covering that with fabric .....

Best Regards
Michael Fraticelli
rocknroll@ucwphilly.rr.com

 

[Rod Gervais]

Michael,

1st - let me introduce myself.

I am a construction engineer located in CT. I perform (for the company I am currently engaged with) the services of Code Consultant (Including Building, Electrical, MEP, Life Safety Code and the ADA.) - I also perform the duties of "valued engineering" on design documents, for the purposes of Structural, Civil, MEP and the Acoustical disciplines.

I am a member in good standing of NFPA.

I have headed up the design teams for the construction of some world class movie studios, recording studios as well as federal museums.

I am occasionally a guest speaker for the AISC at conventions as well as a judge for them for structual design contests.

Presently I am a working on a project located in our state capital which includes a major convention center, high rise hotel, high rise residential apartment building and retail/entertainment facilities. This project covers roughly 33 acres and runs in the 750 million dollar range.

I am also an acoustical moderator on another website. If you were to do a google search on me you would find enough references to verify my credentials.

At least now you know who/what I am.

To answer your remaining questions:

Unfortunately I can't afford the labor, room, or expense of applying more than ONE layer of drywall ..... Soooo - should I caulk or tape the corner joints?

It's simply REHEARSAL room and my goal is to (cheaply) isolate and absorb as sound as possible from getting to the outside world ...

1st of all - from an isolation point of view you aren't going to accomplish much with a single layer of drywall, and the absorbtion is not going to help you.

There are 2 very different things happening here. The 1st is the issue of isolation - for this you need mass.. the loss of the additional 1 1/4" total width and length is not so much that you would notice it much in the end. But the addition of that mass can gain you an additional 20+ of decibel reduction between you and the outside world.

You haven't described your existing construction - but if i assume (I know - I know) an existing shell with 2x4 construction - 16" centers, 1/2" exterior sheathing - vinyl (or clapboard) siding, without interior drywall - and then your inner wall - 2x4 @ 16" centers, with 1 layer of drywall - both walls insulated with R13 and a 1" air space - you're going to acheive roughly an STC rating of around 36 or 37.

That is a weighted average - in the lower frequency range (bass and toms - bass guitar) you will be really down around 10 or 15.......

Add another layer of drywall and this increases to around STC 55 - and about 18 to 20 DB of reduction (once again - weighted average) in the lower frequencies.

If you could add a layer of densglas on the outer surface - then about STC 65 and 25 or 26 (WA) for the lower frequencies. (An additional layer on the inside wall instead of the outside would help you almost this much as well)

THIS IS ALL IF YOU DETAIL THE WORK AS I INDICATED IN THE POST ABOVE.

When you picture that every 10db of reduction is actually cutting the sound in half (this if measured with equipment) and for the human ear - every 6db of reduction SOUNDS 1/2 again as quiet. you can see the gain for even just that 2nd layer of drywall.

That having been said, if you install a single layer of drywall - treat it as i suggested above....... ceiling 1st - 1/4" to 3/8" from walls - caulk the joint Then the 1st wall surface - again leave the gap all 4 sides and caulk, etc. for the remainder of the room. Just make certain that the corner joints where you will eventuall tape the caulk joints are raked slightly below the surface to allow for proper taping.

Then tape as usual to a finished surface.

As far as absorbtion goes, it will do NOTHING to help you isolate from the outside world....... it only deals with the sounds that are already trapped within the room after it is sealed. If you produce 110 decibels of a particular frequency in the room - and you only trap 30 decibles of that - then that is the only reflective you are going to have to deal with.

The more you isolate - the more treatment you will need for the room - and the exact opposite is true as well. With the lack of mass on your walls you probably won't need a whole lot of bass treatment - most of the bass is going to be going out through them.

Understand that (from an isolation point of view) your wall system wouldn't suffice for hotel guest room isolation from a code perspective - however - each and every possible point where air could move through that you seal perfectly will aid you in your task. And you can always add additional layers of drywall in the future when you can afford it.

I hope this gives you a better picture....

Rod

 

[ENIGMACODE]

Hello again Rod - I'd like to pick with this

Hello Rod - thank you for the information in regard your background
Thank you for your patience - I really appreciate you taking the time to help me

Let me try to further clarify what I have to work with, and the dimensions of the room:

Not much space here - I live in a 2 bedroom row home. It's about 80 years old. The room I'm building once again is in the basement/garage below my dining room. The parting walls separating the homes are approx. 18" of masonry. This rehearsal room is only about 10' X 20' (but odd shaped).

I thought it might be best to construct this room completely INDEPENDENT of the existing structure. I've read the importance of this on these posts in the past. So this would be (a room within a room). I thought that by doing this, it would minimize the transmittal of sound. And bear in mind that the garage door is coming down, and in it's place, I'm constructing 2 walls independent of each other approx. 14" apart and the air space in between will be filled with insulation.

I do understand the concept of INCREASING DENSITY to improve isolation of sound. But unfortunately I'm faced with not only funding issues, but structural issues as well. Let me explain:

Unfortunately in order to increase head room, about 1/4 of the room's cieling joists may have to be 2X3's. So by resting the cieling joists atop the walls (with NO support from the existing cieling thru guy wires etc.), this neccesitates 12" centers for more strength, but still perhaps not enough capacity for EXTRA WIEGHT. Thus perhaps the need to keep things to one layer of drywall.

But are you suggesting that if I use incorporate extra support from the existing cieling and install 2 layers of 1/2'' drywall on the cieling, this would be a BETTER bet than if I construct the room WITHOUT contacting the existing cieling??? i.e. total isolation from the exsiting structure?????

And you said:
"Understand that (from an isolation point of view) your wall system wouldn't suffice for hotel guest room isolation from a code perspective"

Rod - wouldn't you agree that my original plan to build just a simple room within a room constructed solidly, and treating the inside walls with auralex panels, is definitely far BETTER than just jamming the garage with equipment, (as is), and cranking up the music??? Can you agree with this?

If I've given a better explanation as to my constraints, can we pick up with our discussion in regard to drywall joints and taping?

You Mentioned:
"Install the 1st ceiling layer...... leave this 1/4 to 3/8" from the wall framing. Caulk this joint."
"Install 1st wall layer...... leave this 1/4" to 3/8" from the wall/ floor/ ceiling - caulk this joint...... repeat this for the remaining 3 walls......"

"Apply a 1st coat of joint compound and tape to all joints except corners (those have the caulk)"

"That having been said, if you install a single layer of drywall - treat it as i suggested above....... ceiling 1st - 1/4" to 3/8" from walls - caulk the joint Then the 1st wall surface - again leave the gap all 4 sides and caulk, etc. for the remainder of the room. Just make certain that the corner joints where you will eventuall tape the caulk joints are raked slightly below the surface to allow for proper taping.Then tape as usual to a finished surface."

Rod - are you saying that I should keep the drywall on all the walls and the cieling from ever actually joining each other? Leave these gaps ALL around, and just CAULK ALL the gaps?? And NOT apply corner tape and joint compound over the gaps? Just LEAVE the caulked joints EXPOSED? And if I've got this right, is this method still a good idea, (still neccessary), even if I only install ONE layer of drywall?

And to sum up:
So then NO gaskets are neccessary (floor plate or top plate)
Just go ahead and assemble the room conventionally with coated screws - but if I want to add a little glue between the plates - no accoustical harm done - and I may add a little strength by doing so?

AND
Should I caulk the corners on the floor (where the walls meet the floor?)

Thank you again!
Best Regards
Michael Fraticelli
rocknroll@ucwphilly.rr.com

 

[Rod Gervais]

I thought it might be best to construct this room completely INDEPENDENT of the existing structure. I've read the importance of this on these posts in the past. So this would be (a room within a room). I thought that by doing this, it would minimize the transmittal of sound. And bear in mind that the garage door is coming down, and in it's place, I'm constructing 2 walls independent of each other approx. 14" apart and the air space in between will be filled with insulation.

OK - this is a big plus........ a totally seperate structure is always the best......

Unfortunately in order to increase head room, about 1/4 of the room's cieling joists may have to be 2X3's. So by resting the cieling joists atop the walls (with NO support from the existing cieling thru guy wires etc.), this neccesitates 12" centers for more strength, but still perhaps not enough capacity for EXTRA WIEGHT. Thus perhaps the need to keep things to one layer of drywall.

But are you suggesting that if I use incorporate extra support from the existing cieling and install 2 layers of 1/2'' drywall on the cieling, this would be a BETTER bet than if I construct the room WITHOUT contacting the existing cieling??? i.e. total isolation from the exsiting structure?????

Actually - yes I am in this case....... you need the mass...... and if you can't acheive it with the seperate ceiling - then you need to use the existing.

In your case I would probably recomend the use of RISC 1 clips and hat sections to frame down the ceiling........ that would be the best case...... and if cost does not allow that - then use Resilient Channel and 2 layers.

You do need the mass........ there is no way to escape that - you can't do anything to change the laws of Physics....... so if the direction you're heading won't support the load - then you need to figure out another way to get the job done.

And you said:
"Understand that (from an isolation point of view) your wall system wouldn't suffice for hotel guest room isolation from a code perspective"

Rod - wouldn't you agree that my original plan to build just a simple room within a room constructed solidly, and treating the inside walls with auralex panels, is definitely far BETTER than just jamming the garage with equipment, (as is), and cranking up the music??? Can you agree with this?

Yup......... I sure can agree with that - anything you do is better than doing nothing at all........ but remember - the treatments do NOTHING for isolation (let that be your mantra) and that is what we're discussing here...... isolation.

Another option you can consider is just adding some isolated supports from the 2x3's to the existing structure - but in the end - you will need mass mass and more mass.......... nothing in the world changes that.....

The concrete wall between units is great mass..... but you also have the upstairs to deal with - and that garage door - so in addition to the double wall and seperate ceiling you picture - you need mass to deal with low frequencies......... as i mentioned above - this is a simple law of physics...... nothing you or I ever do will make that change..... and seeing as a wall is not a diode - this works in both directions - whatever sound can escape can also enter.......

Rod - are you saying that I should keep the drywall on all the walls and the cieling from ever actually joining each other?

YES................ this is actually quite important.

Leave these gaps ALL around, and just CAULK ALL the gaps?? And NOT apply corner tape and joint compound over the gaps?

NO..... you do not JUST CAULK........ on the final layer - finish tape everything as usual........ that's why I said to rake the caulk back slightly from the face of the drywall - so taping as normal would not be a problem

The idea here is to stop every place that air could possibly pass through - because where air can go noise can go.

If you look at the buildings you inspect - you will find that very few sound walls have anywhere near the isolation they are designed to have. That's because the installation methods (typical construction techniques) leave enough air passageways to allow for about a 20db loss in effectiveness.

That number is very real - and has been tested and verified by USG.

Now picture that this 20db loss translates to the wall only being 25% of it's effective design if you test it with equipment......... and only roughly 12 1/2% if you listen to it (in other words, the sounds to your ears would seem to be 300% louder than a perfectly sealed wall).

Trust me - whether it's one layer or 3 - you want to seal each and every layer at it's perimeter......

So then NO gaskets are neccessary (floor plate or top plate)
Just go ahead and assemble the room conventionally with coated screws - but if I want to add a little glue between the plates - no accoustical harm done - and I may add a little strength by doing so?

No harm with adhesive between the plates - and no gaskets are required.... you got it...........

Should I caulk the corners on the floor (where the walls meet the floor?)

Yes - you want to caulk all 4 sides of each wall........

Sir, I understand your situation - believe me I do, but i cannot recomend this to you any more strongly - you need to figure out a way (both from a structural and a budget point of view) to make it 2 layers.

Rod

 

[ENIGMACODE]

Hello again Rod and others-Good Dialog-Great Help!

Rod ....

I'm gonna take your advice and beef up the entire ceiling joist assembly in the free-standing room, and look for the existing cieling joists above to construct some kind of makeshift bracing to help bear the load of the drywall on top of the new inner walls..... but I don't think I can afford the extra expense and additional construction time in utilizing 'RISC 1 clips' or 'Resilient Channel'. Can't I achive similar results by constructing some kind of makeshift bracing to be attached from the existing joists above then down to the new celing joists? I can stagger them to provide the extra support to minimize any sag in the newly completed drywalled ceiling.... sound ok?

Only problem now - do I now need to look at incorporating some gasketing since I've breached contact to the exisiting floor/ceiling joists above - hence re-established contact to the outside world - i.e. my dining room above?

Give me your thoughts on that..... and bear in mind once again, I know there are specific products to care of this: 'RISC 1 clips' or 'Resilient Channel' etc.... BUT as I said, I'm GOOD with improvisation, but limited in budget, and perhaps I can come up wth something just as good? (via a home-made brace with gasket) If it's entirely neccessary???

Thanx Rod - YOU'RE A GENTLEMAN!
Best Regards
Michael Fraticelli
rocknroll@ucwphilly.rr.com

 

[Rod Gervais]

Rod ....

I'm gonna take your advice and beef up the entire ceiling joist assembly in the free-standing room, and look for the existing cieling joists above to construct some kind of makeshift bracing to help bear the load of the drywall on top of the new inner walls..... but I don't think I can afford the extra expense and additional construction time in utilizing 'RISC 1 clips' or 'Resilient Channel'. Can't I achive similar results by constructing some kind of makeshift bracing to be attached from the existing joists above then down to the new celing joists? I can stagger them to provide the extra support to minimize any sag in the newly completed drywalled ceiling.... sound ok?

Why not use these:

http://www.silentsource.com/specprod-hangers.html

The ARH-1-20 is rated for a 65# max load.

For a ceiling that's going to weigh about 7.5 psf the 1-20 will be good for almost 9sf....... so you will only need about 15 of them to make this work (remember the perimeter wall is carrying 1/2 of any spaned load itself.)

From a cost point of view this will only run about 50 dollars..... make room in your budget for it - that way you are still maintaining your isolated structure without getting involved in trying to seperate your wall assembly.

It's actually a one or the other situation here........ do this and you don't need the RISC or RC -

By the way, thank you for your kind words.......

Rod

 

[ENIGMACODE]

Moving right along thanx to you Rod

Yes Rod ... how's thing's?

Well - I did check out the 'Silent Source Hangers' for those existing overhead joists - GREAT invention - good stuff on their site ..... reasonably priced too ....

However I realized that I probably don't even have enough headroom to utilize them (suspend them) ....
This row home is tiny ..... not unlike others in the City ....

Soooo, I guess I have to come up with a do-it-yourself bracket after all ....
But that's ok - I Love to improvise, and with your expert direction, and advice I feel more and more comfortable that I'm headed in a good direction ....

I should take a few photos for you to see so that I can illustrate the low headroom. But basically I'm gonna have to attach a brace to some of the sides of the existing overhead joists, and drop them down a few inches to catch the New joists to assist in the weight load from the newly drywalled cieling below. What I was thinking was that I could install braces (probably 2X4's), and install gaskets (rubber padding) between the 2X4 brace, and the side of the existing overhead joist - and maybe down by the new cieling joist if neccessary too - know what I mean? How's that sound?

And in regard to the layers of drywall, I'd like to mention another approach that I'm considering, but I'm sort of preparing myself for a 'possible friendly lecture' from you

Here goes:
I know you emphasized the importance of 'DENSITY'

Well, I think at this point you know me well enough to know I'm reasonably knowledgeable, but have budgetary and labor constraints. Good help is expensive, and I'm not as young as you think...

I have to say that I am considering applying only one layer of 5/8" drywall ALL around (walls and ceiling) as opposed to 1/2".

Rod - Can I have your blessing specifically with the 5/8" as opposed to 1/2"?
Is there a significant advantage between 1/2" and 5/8" drywall? And at least
the extra support braces will aid in the distribution of the load.

And Rod I will be following your advice very closely concerning the proper caulking method in regard to the drywall - in fact it would be great to see an illustration somewhere that clearly shows the gap and the edges caulked before the tape is applied...

Anyway, I'll be taking a few photos in the upcoming days, and hopefully you won't grow tired of our discussion - and we can go from there ....

Rod - I couldn't have done this without you

We'll be in touch ...
Best Regards
Michael Fraticelli
rocknroll@ucwphilly.rr.com