Project studio door knob (most boring question evar!)

[jayf]

I am building a new project studio in my garage, and will have a door between the studio and the rest of my house. The door will be solid, and have pemco gaskets / seals for sound isolation.

What's the most sound proof way to have a door knob / handle on this door? Should I:

a. use a regular door knob, because it's not a problem?

b. use a regular door knob, but do _____ to make it more sound proof?

c. use a handle that mounts on the surface of the door, but doesn't go all the way through?

d. other?

(btw, I know about using two doors / communicating doors, and am already doing that on the door to the outside. It's maybe an option on the door to the house, but it's not currently in the plan.)

[helmuth]

b: http://www.muppetstore.com/shopexd~cate ... id~313.htm

[goldstar]

J

The best sound seal is w/ c. Use a surface mounted pull handle to open it.

By not boring a 2" hole thru the door (for a standard lockset) you save a bit of isolation. The down side is that you probably need to use a door closer to keep the door closed, and they run $75 and up and are a bit of a nuisance to install.

Frank

[Professor]

There are three doors in the studio here that connect acoustic spaces together - from control to machine room, from control to airlock, and from airlock to live room. They are all setup with pull handles. They are also setup with internal dead-bolt locks, which may not be a typical Russ Berger design (it might have been at the school's request for security) I really can't say. But they are sealed fairly well and don't take much strain... indeed they hardly see any use. I tend to just pull the doors firmly against the seals, and I don't flip the lock into place during sessions.
Oh, they do have auto closers, but they are tuned pretty loose - meaning that they can't pull a firm seal since the spaces are pretty much air-tight.
You might take a similar approach by just mounting on a pull handle, and only worry about a lock mechanism if you're concerned about security.

Of course, you also mentioned the door will be solid. Now do you mean that it's a solid-core door, or is it a hollow frame door packed with sound absorbing material? Since a solid wooden plank will translate sound very well, while a hollow metal shell filled with fiberglass or foam will provide isolation. If the door is solid, then the lock mechanism won't act any different than the rest of it, so long as it doesn't rattle.


-Jeremy

[;ivlunsdystf]

b: http://www.muppetstore.com/shopexd~cate ... id~313.htm

Funniest post of the week.

[jayf]

Thanks for all of the advice.

Of course, you also mentioned the door will be solid. Now do you mean that it's a solid-core door, or is it a hollow frame door packed with sound absorbing material? Since a solid wooden plank will translate sound very well, while a hollow metal shell filled with fiberglass or foam will provide isolation. If the door is solid, then the lock mechanism won't act any different than the rest of it, so long as it doesn't rattle.

I was planning on using a solid-core door on the assumption that more mass = more sound absortion. I know that there are very expensive acoustic doors that are metal and filled with acoustic insulation, but will a standard foam insulated metal door provide better isolation than a solid-core wood door?

[Rod Gervais]

I was planning on using a solid-core door on the assumption that more mass = more sound absortion. I know that there are very expensive acoustic doors that are metal and filled with acoustic insulation, but will a standard foam insulated metal door provide better isolation than a solid-core wood door?

Jay,

No - A foam insulated door will be useless for low frequency isolation - as will any hollow core door that you fill with any foam type of material. The only way a foam filled door might possibly beat out a solid core door would be when considering impact noise - although that would entirely depend on how the honey-comb inside of the door was manufactured and attached to the 2 faces.

When it comes to low frequencies - what matters most (in a door) is mass ((coupled (of course) with air tight seals))..

You can improve on you door's performance by adding 8 pound sheet lead covered by a sheet of MDF or finished plywood (if you wish) which gives you a heck of a lot more mass with very little thickness added.

Don't worry about frequencies above making it through the door - any assembly that can handle LF transmissions well will kill the upper frequency transmissions in the process.

Sincerely,

Rod

[Professor]

Well let's be honest - low frequencies are going to travel through damn near anything you put in their way.
But the general rule for acoustic control is to have a very dense surface, followed by a dead-air space, followed by another dense surface. Think of what we do for control room windows or studio walls with separate studs. In particular, consider the staggered stud walls. The reason we don't want the same wall stud in contact with both sides of the wall is that the studs will translate sound through the wall, but the staggered studs will translate the sound into the dead space between the walls.
That's why acoustic doors aren't a single block of wood. They are steel sleeves with acoustic filler inside.
Of course, specific acoustic doors are pricey, but an insulated steel door, or an insulated wood door, designed for exterior use on a home should be a better equivalent to that design than a solid block of wood designed for an interior connecting door. The easiest thing is to go Home Depot or some local shop with a good door selection and start knocking on them. You'll be able to tell which doors are 'acoustically solid' and the prices will be right there for you to compare.

-Jeremy

[jayf]

Thanks Rod--that's helpful (and, it reminded me that I wanted to buy your book, which I just now ordered!)

[Rod Gervais]

Well let's be honest - low frequencies are going to travel through damn near anything you put in their way.
But the general rule for acoustic control is to have a very dense surface, followed by a dead-air space, followed by another dense surface.

Professor,

you're right about how we build walls - we use MAM systems..... BUT - you can control low frequency transmissions strictly through the use of Mass Law - and mass law is applied when dealing with single membrane systems.

Let's let reality set in her for a moment -

Terma-Tru is a major manufacturer of both steel and fiberglass resiential exterior insulated doors, here's their data for sound isolation with their products:


........................Product............................STC Rating
Therma-Tru Fiber-Classic Door Systems............25
Therma-Tru Smooth-Star Door Systems............25
Therma-Tru Premium Steel Door Systems.........24
Therma-Tru Construction Series Door Systems.. 24

Now - a standard grade interior solid core door - with weatherstripping, achieves about an STC 26 to 30 depending on the manufacturer.

Solid Core doors with an MDF interior are around STC 31.

Solid Code Interior wood Sound Doors will acheive from STC 40 to STC 53- the high end from a company called Krieger Specialty Products.

Steel Isolating Sound Doors - Overly Doors (one of the leaders in the market) STC 43 to 57.

Point - the steel doors from Overly (or any other major manmufacturer) are NOT foam filled - they are (rather) typically packed with rockwool - around a 2.5pcf density or greater.

Think of what we do for control room windows or studio walls with separate studs. In particular, consider the staggered stud walls. The reason we don't want the same wall stud in contact with both sides of the wall is that the studs will translate sound through the wall, but the staggered studs will translate the sound into the dead space between the walls.

You are speaking apples compared to oranges.......

That's why acoustic doors aren't a single block of wood. They are steel sleeves with acoustic filler inside.

Quite simply sir - and meaning no disrespect- you are mistaken - you can purchase solid core wood doors (which are filled with an extremely dense non foam filler) and be within a couple of dB of isolation compared to steel. The 2 sides are directly coupled.

Of course, specific acoustic doors are pricey, but an insulated steel door, or an insulated wood door, designed for exterior use on a home should be a better equivalent to that design than a solid block of wood designed for an interior connecting door. The easiest thing is to go Home Depot or some local shop with a good door selection and start knocking on them. You'll be able to tell which doors are 'acoustically solid' and the prices will be right there for you to compare.[ /quote]

Again sir - you are mistaken - but that is because you are now trying to compare apples and oranges.

Which will make the better sound isolation wall assembly?

Single 2 1/2" steel studs - 24 ga - with 2 1/2" 3 pcf density rockwool insulation in the cavity and 2 layers of 5/8" drywall on each face?

or

A double wall with 2 1/2" studs- 12" air space - with 2 1/2" 3 pcf density rockwool insulation in both cavities and 1 layer of 5/8" drywall on each face?

The fact of the matter is that it all depends on what you're measuring -

If impact noise is your concern - then wall 2 will out perform wall one all day long.

BUT - if impact noise is NOT a concern - if our concern is air-borne transmissions - the wall one will out-perform wall 2 all day long.

You cannot tell the quality of a sound isolating door through the use of the knuckle test.... it just doesn't work that way when dealing with mass alone.

Take a door that weights around 65 pounds - a standard commercial grade 3'-0" x 6'-8" x 1 3/4" solid core wood door that will have a rating as high as STC 31 - now - leave the door exactly the same size- but double the weight of the door - and you will now have an stc rating of about 37 - and double that again for an STC 43 and a door that weighs about 260 pounds..

The door never increases in size - it never develops an air space - it does not de-couple the 2 faces - all it does is double the mass twice to acheive an increase of 12dB of isolation - an increase of 200% effeciency..........

Perhaps you should rethink the whole thing.

Sincerely,

Rod

[samuelowen]

e. stab

i recommend the handle pull type, in seriousness.