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Building a home studio in old house with plaster walls, knob and tube wiring
Old 12th November 2009
  #1
Building a home studio in old house with plaster walls, knob and tube wiring

Hello, I am going to be building a home studio space in an old house I just bought. The studio room is 15'8" x 11' with 8' ceilings.

After studying for weeks I figured my best bet would be to remove the plaster and lathe from the walls in the studio room, add insulation between studs and layers of drywall with Green Glue between... till I discovered that the wiring in my walls is knob and tube meaning I would not be able to add insulation without first addressing the wiring.

I realize that this would be a great time to bring in an electrician to update the wiring in the walls, but am thinking that it might be easier and provide further isolation from the rest of the house to build false walls over the existing plaster walls of the studio room and run new grounded wiring to the studio completely bypassing and not disturbing the existing knob and tube wiring to the rest of the house.

I notice false walls are mentioned in the current 'square room' thread and Glen's idea of fabric covered trapping seems like a good solution to me.

Any thoughts on false walls over plaster walls? Dealing with, replacing or avoiding knob and tube wiring?

Thanks!
Old 13th November 2009
  #2
Gear Nut
 

What does your service panel look like now? If you have that old of wiring it might be time to upgrade your service. I just did, on a rental property. $1500 for 100 amp service. Usually if you upgrade your breaker box they will add gfi's in kitchen and baths. THEN you could think of running your your new wiring for studio. But by all means do your new walls decoupled from exiting. And rc on ceiling atleast. It'll be worth it.
Old 13th November 2009
  #3
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jhbrandt's Avatar
Quote:
Originally Posted by gn87berner View Post
If you have that old of wiring it might be time to upgrade your service. I just did, on a rental property. $1500 for 100 amp service. Usually if you upgrade your breaker box they will add gfi's in kitchen and baths. THEN you could think of running your your new wiring for studio. But by all means do your new walls decoupled from exiting. And rc on ceiling atleast. It'll be worth it.


I agree.

Your lathe and plaster walls have a lot of mass, which is very good at blocking LF sound. I would use them.

However, currently you have 1379 cu. ft. (below the ideal minimum of 1500 cu. ft.) and the mode plot isn't too bad with mode bunching at 155Hz & 210Hz. If you build out the walls with a gap of 1" using 2 X 4 construction & 5/8 drywall, that would bring the walls in 5 1/8 inches on all sides giving you final dimensions of 14' 9 4/3" X 10' 1 3/4" X 7' 11 3/8". Add one layer of 5/8" gypsum board on the ceiling. Your volume drops to 1194 cu. ft. which is really way below what anyone should recommend. But the mode plot really isn't too bad. With proper acoustic treatment this could work. (I can't believe I'm saying this...)

So the choices are: 1. tear out the plaster, install new electric, insulate, drywall (I highly suggest 2 layers 5/8") & finish. 2. LEAVE the plaster, add one layer of 5/8" drywall, install 'cut-out' boxes and install new wiring, finish (no insul). and 3. Build additional walls, install new electric in new walls, insulate, drywall (at least one layer of 5/8"), finish.

Pros and cons to each suggestion.
1= probably the best in terms of acoustics and good finish - but worst as far as cost is concerned. (not to mention that it's a bloody mess.. if you do this wear a breathing mask. That dust is a hundred years old. )
2= also good acoustics (bigger room), but finish may suffer because of existing trim not fitting the additional layer of gypsum - and a little more inventive planning on the part of the electrician.
3= The best in terms of Isolation, ease of wiring, and finish, but the worst in that the smaller room will produce wider spacing between modes. BUT... the new walls (2 X 4 construction) may actually add absorption at the low end so this problem could be negligible.

I know nothing about this 'green glue' stuff. Can anyone give me proven specs on this. It sounds like the rubber between the 2 doors glued together thing... "Yes, I know it's heavy. But it's ugly too!" ~shrug~

If isolation is what you are looking for then choice #3 would be the one.

Mass + Airspace + Mass = Isolation
not mass + glue + mass

Check out GIK Acoustics presents Acoustics Primer: Some Basics on Acoustics.
and RealTraps - Acoustics Information -- also JavAkustik - Acoustics Control Products & Consulting

Good luck!
Old 13th November 2009
  #4
Gear Nut
 

Quote:
Originally Posted by jhbrandt View Post


I know nothing about this 'green glue' stuff. Can anyone give me proven specs on this. It sounds like the rubber between the 2 doors glued together thing... "Yes, I know it's heavy. But it's ugly too!" ~shrug~
There's a bunch of info and testing here:

Green Glue is your soundproofing and noise reduction material

They talk about it alot over at the JohnSayers forum. I think it's also mentioned in Rod's book. Seems many people have had success with it between layers of Drywall. I don't think it's snake oil, but haven't used it myself, and it's not cheap!
Old 14th November 2009
  #5
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jhbrandt's Avatar
Thanks Lomky! I'll check it out.
Old 14th November 2009
  #6
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avare's Avatar
 

Green Glue

Green Glue is a visco elastic material that is used for Constrained Laer Damping (CLD). The concept is not new, being mentioned as early as 1973 in Snow's fantastic paper. There are American, Australian, French, and Swedish companies making similar products. Tehy are not all equal.

Andre
Old 17th November 2009
  #7
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jhbrandt's Avatar
Ok, Research complete.
I'd like to rephrase what I said before:

So the choices are:
1.
tear out the plaster & trim, install new electric, insulate, drywall 2 layers 5/8" sandwiched with Green Glue, trim & finish.
2
. LEAVE the plaster, add one layer of 5/8" drywall with Green Glue, install 'cut-out' boxes and install new wiring, finish (no insul). and
3
. Build additional walls using steel studs, air space of approx 4", install new electric in new walls, insulate, drywall two layesr of 5/8" sandwiched with Green Glue, finish.

You also must do the ceiling... at least one new layer of 5/8" with Green Glue.

Pros and cons to each suggestion.
1= probably the best in terms of acoustics and good finish - but worst as far as cost is concerned. (not to mention that it's a bloody mess.. if you do this wear a breathing mask. That dust is a hundred years old. ) Not as good at Isolation.
2= also good acoustics (bigger room), but finish may suffer because of existing trim not fitting the additional layer of gypsum - and a little more inventive planning on the part of the electrician.
3= The best in terms of Isolation, ease of wiring, and finish, but a little worse acoustics in that the smaller room will produce wider spacing between modes. BUT... the new walls may actually add absorption at the low end so this problem could be negligible.

All things considered... I think I would do plan 3 because you are going to want to install plenty of bass trapping anyway for that size room... so room modes will not really be an issue.

Good luck there.. and thanks, Andre! "Ahh Bu-Leave!!" heh "Yayusuh!!"
Old 17th November 2009
  #8
Quote:
Originally Posted by gn87berner View Post
What does your service panel look like now? If you have that old of wiring it might be time to upgrade your service. I just did, on a rental property. $1500 for 100 amp service. Usually if you upgrade your breaker box they will add gfi's in kitchen and baths. THEN you could think of running your your new wiring for studio. But by all means do your new walls decoupled from exiting. And rc on ceiling atleast. It'll be worth it.
Service panel is 100 amps... parts of the house seem to have been updated at some point. Most of the outlets in the house are ungrounded and I would assume Knob and Tube... but after chasing some wires over the weekend I discovered that a 20amp breaker marked "upstairs outlets" that leads to grounded outlets in both of my studio rooms... as far as i can tell it's a recent addition and romex wiring.
Old 17th November 2009
  #9
Quote:
Originally Posted by jhbrandt View Post
1= probably the best in terms of acoustics and good finish - but worst as far as cost is concerned. (not to mention that it's a bloody mess.. if you do this wear a breathing mask. That dust is a hundred years old. ) Not as good at Isolation.
1 would have been my first choice.. till I realized how much work it requires. Plus the mess... lost the fight with my girlfriend and the wood floors are being refinished NOW... not after I had a chance to complete the studio walls. Anything I do from this point on will have to take potential harm to new floors under consideration.

Way ahead of you with the mask... all of the dust from pulling up carpet and exploring the plaster walls is already starting to mess me up.
Old 17th November 2009
  #10
Gear Nut
 

Now you are getting in to it. Any available slots in your panel? Any way to run new circuits to your studio? There's alot to wiring in a studio. You "might" be able to get buy with that 20 amp breaker, but more would be better. Also running homeruns for each outlet to reduce the chance of hum. Research star grounding. If you were to demo/insulate/build new walls decoupled/insulate a couple layers 5/8's with GG, you'd be on your way to having fair isolation. Your ceiling is still the biggest concern. I would definitely demo. Where I live you can do your own electrical as long as you are not selling and not for public. An electrician will cost an arm and a leg. Maybe get someone who can help supervise and you do it, after research. PM me if you want.
Old 18th November 2009
  #11
Quote:
Originally Posted by gn87berner View Post
Now you are getting in to it. Any available slots in your panel? Any way to run new circuits to your studio? There's alot to wiring in a studio. You "might" be able to get buy with that 20 amp breaker, but more would be better. Also running homeruns for each outlet to reduce the chance of hum. Research star grounding. If you were to demo/insulate/build new walls decoupled/insulate a couple layers 5/8's with GG, you'd be on your way to having fair isolation. Your ceiling is still the biggest concern. I would definitely demo. Where I live you can do your own electrical as long as you are not selling and not for public. An electrician will cost an arm and a leg. Maybe get someone who can help supervise and you do it, after research. PM me if you want.
Not sure about available slots... will have to check it over again.

I don't know if the ceiling will be a problem. My studio will be on the second floor with an attic above the studio space so I am mostly concerned with isolating the walls.

The city I'm in (Omaha) seems to be against doing your own electrical.
Old 18th November 2009
  #12
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jhbrandt's Avatar
Quote:
Originally Posted by aarongum View Post
... the wood floors are being refinished NOW... not after I had a chance to complete the studio walls. Anything I do from this point on will have to take potential harm to new floors under consideration.
You can safely build over the new floor if you are careful. Use builder's paper to cover the new floor and build your new walls. You really must also do the ceiling. Quite a bit of sound comes and goes through there.

I guess #3 is back in the running then...
-----
About ground loops and wiring:
And actually, home runs with the electrical often do not result in less hum, but more. Unless they are run in the same conduit all the way to the mains box, separate home runs create additional loop area which is what, in fact, picks up the hum.

When wiring, pay attention to loop area with all grounds.
Old 18th November 2009
  #13
Quote:
Originally Posted by jhbrandt View Post
You can safely build over the new floor if you are careful. Use builder's paper to cover the new floor and build your new walls.
Yeah, good to know. I keep thinking of new floors as being delicate but with a little caution there should be no problems.

Quote:
Originally Posted by jhbrandt View Post
You really must also do the ceiling. Quite a bit of sound comes and goes through there.
Ugh, I was hoping to not have to touch the ceiling... but I can not argue the potential for sound transmission though it.
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