200mm Concrete slab db transmission loss

[Eric.Desart]

Bob,

Does anyone know if it is it easier to open a door with rubber compression seals around the thin side of a door, or with felt around the thin side of the door?

I'm not sure what you mean here.
Sealing a door with felt is based on an entirely different acoustic principle than rubber gaskets.

Felt is NO insulation material but absorption material. This even means that you don't need pressure on it. It absorps as splitter silencers do.
But that also means that the resulting TL depends on several factors.
If you should use a felt with a width of 1/2" as substitute for a rubber gasket of a simular size, I can assure you that the felt is a very poor choise.
If you use felt as an absorber to seal the door you should use the complete door thickness to create a long absorption path. And the insertion loss then is mainly defined by gap width versus gap length. So this technic is mostly used (if used) as an addition to, or supported by other types of sealing. This technic also solves potential resonances (modes) in the gap.

But the best thing is still good rubbers. One of the main problems with a good door is designing it to get enough pressure on the rubbers.
And that's defined by the quality and type of the latch (+ rest design of course), which should build up pressure in a conical manner.

Those magnetic sealings are an in between solution. In fact they are meant to solve inaccuracies and guarantee a perfect mid, high frequent sealing.
But the design of a magnetic seal is as such (mainly designed for thermal purposes) that you have a feet and this magnetic stripe which are connected by a VERY thin elastic housing (allowing relative large expansion), with relative poor insulation values. So a magnetic sealing can solve large gaps but at the expense of TL. (I hope you understand what I mean here)

So counting on magnetic sealings for very high insulations doesn't feel right to me.
When having a sound lock with 2 seperate doors of around 30 dB than it doesn't matter that much.

Professional acoustic doors (ca 50-52 dB doors) with double sealing will show a total pressure on the rubbers easily exceeding 150-200 kg (330-440 lb). This only works with good door accessories (hinges and latches).

Does this work easily? Yes it does.
I've used lots of such doors in TV (and other) studios. Those on TV super sexy looking assistants who have to guide people to their places and different rooms, if you see them in real live without/before make-up, it are almost children (no disrespect meant) with a weight of 45 kg (100 lb). The door leave is about 2.2 to 3 times their own weight.
Well a TV station can't permit herself to have those assistants starting a fight (in front of public, visitors, artists, VIPs) with every acoustic door they encounter. They only have to learn to act calmly (mass ratio door versus assistant)

So it's all a matter of defining your goals and targets and adjusting your design in accordance to that.

Best regards
Eric

[Bob]

Eric, that was a wonderful post. It clearly ansered both the question I asked, and the question I should have asked.

The bit about " total pressure on the rubbers easily exceeding 150-200 kg (330-440 lb). " was an interesting statistic. Puting pressure on rubbers has the double good effect of increasing the seal and narrowing the gap. Your post has me wondering about my door plans (overkill, underkill, just right, better/cheaper way, proven known ways).

I seem to recall when I asked about Paul's door's seal corners, he suggested that when the door was closed the pressure of the door would push the seals into each other further tightening the corners.

When having a sound lock with 2 seperate doors of around 30 dB than it doesn't matter that much.

Yesterday, my door system design was:
a) double doors, with an 8" threshold
b) each door consisting of plywood/lead/plywood, flat (no bank vault), with felt around the door. At the hinge side of the door 4" of lead is replaced with plywood.
c) no door handle, just a pull knob on one side. The other way, you just push open. No screw or metal goes all the way through the door.
d) attached to the doors, four sided magnetic seals as shown at the bottom of http://www.thomasregister.com/olc/65861502/a.htm . The magnets hold the door shut.
e) 2" of 703 on the back of one of the doors, in the air lock between the doors.
f) ball bearing hinges
g) a 2x6 on all four sides of the door jamb (the air lock between the doors) with metal attached to both 1.5" sides for the magnetic seals.

Assuming a wall/room construction as shown in
a) http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=55
b) http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=45
c) http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=44

What would you'al (anyone at studiotips) recommend for a door system ?

Purpose of the door
a) to reduce noise from inside getting out. Probably around 85db.
b) to eliminate noise from the 50db furnace from getting in. http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=23

[Eric.Desart]

Bob,

I leave those details to others. That's a complete job checking this in detail.

What strikes me is one number: 85 dB.
What do you mean by that: Music sound with low frequent content (typical disco like or studio sound)?
Well it's easy to write 85 dB.
I give you an idea:
Two concrete bunkers with concrete bricks of 1 foot, plastered with > 1/2 inch concrete one-sided. Cavity between bunkers ca 2 ft. Bunkers perfectly decoupled via huge springs.
Well that gives you ca 85 dB for disco-like music.
To preserve that: any cable, any duct, ventilation, any whatever must be perfectly designed not to destroy this value.

Can you translate this arithmetically?
Sound intensity blocking including weaker points with a factor 10^8.5. = 1/316,227,766

Best regards
Eric

[Bob]

Hi Eric

Sorry, I should have written it as 85db(C), as a noise level in the air inside the room. I'm not talking about an 85db TL.

It's music sound, measured with a radio shack sound level meter set to weighting C showing a reading of 85db. It's sort of a typical listening level. Actually it's a bit loud.

I think my warm air HVAC will be fine (recently changed to have several long S-runs). My return air may or may not be ok. There are no other feeds or holes that I'm worried about (e.g. no electrical on sensitive walls).

[Eric.Desart]

Bob:

The dB(C) weighting is indeed a much better weighting than dB(A).
But it still does not represent disco-music.

Do you mean that you play at a level of 85 dB(C) in a control room or tracking room?
Or do you need insulation of 85 dB(C)?

Is this measured as slow or as fast?
85 dB(C) is a very low emission level.

Your fast levels will be as average between 3 to 5 dB higher than the slow level.
But we hear faster than that. So meaning the audible levels are another x dB higher than the Radio Shack can measure.

Best regards
Eric

PS: I still have a lot of things that (IN THE FUTURE) I'll put on web pages. But as usual, I start with something. That becomes too time consuming and then it hangs around (in any stage), waiting for the holy ghost or something.

[Bob]

Do you mean that you play at a level of 85 dB(C) in a control room or tracking room?

yes.

Or do you need insulation of 85 dB(C)?

no. I need insulation at a minimum of 50db(C-slow)

Is this measured as slow or as fast?

slow

[Bob]

Since the idea is to try to build doors to match the room, here's some TL numbers for the room.

This is relative to the drawing that I showed at
http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=55

The wall on the right, according to http://www.pac-intl.com/pdf_test/test_RAL_TL01-212.pdf , should perform at
63hz 23db, 125hz 47db, 250hz 56db, 500hz 60db, 1khz 66db, 2khz 64db, 4khz 73db

The ceiling, according to insul48SA.exe, should perform at
63hz 35db, 125hz 46db, 250hz 51db, 500hz 57db, 1khz 62db, 2khz 65db, 4khz 70db
Assuming that it doesn't couple to the i-beam too much.

For the 8" poured concrete neighbour wall, I really guessed with insul48SA.exe. First panel (200mm of poured reinforced concrete, density=2100 kg/m^3, GPa=35), resilient railbar (not RSIC), 150mm (6"), 2 layers of 14mm gypsum to get
63hz 42db, 125hz 54db, 250hz 65db, 500hz 73db, 1khz 81db, 2khz 89db, 4khz 97db.

But the problem with the neighbour wall isn't the bottom 7.5' of it (the poured concrete foundation). The problem is probably going to be the top 8". The joists are those top 8" and the wall there is not solid concrete, but rather {5/8 gypsum not sealed, 2x8 spruce not sealed, two layers of 5/8 gypsum (fire block air tight), 2x8 spruce not sealed, 5/8 gypsum not sealed. Also the joists in my basement may be touching the joists in the neighbour's basement.

For the floor, I'm not even going to guess. How much noise actually goes into the earth isn't the problem, but how much flanks sideways may be. I figure that because the floor is heavier than the walls, that might offset the fact that the floor isn't as decoupled as the walls (pucks vs RSIC) and it'll turn out equal. The gap ranges from 40mm to 130mm, giving an average of 65mm.

[Eric.Desart]

Bob,

I find it confusing that you discuss your topic in 2 forums. (or more?).
It's like one needs to read them all to know who said what.

It's not clear how your door is build and which rooms it connects.
Or I maybe miss one of your pictures.

If there are neighbors those top 8 inches look not good.

Filling with expanded foam is by definition a bad idea with acoustics (hard and closed cells = no good for nothing. If it does something it's mostly negative).

The acoustic mat in your floor is a bad idea here.

When designing a door: do you use a common frame? Seperate supports?

I advice to continue in 1 group.
Rod has a lot of practical experience.

If insulation is weak and you have weak spots, why not making it easy and use an additional layer or more on the inside?

Best regards
Eric

[Bob]

Hi Eric (et al):

I find it confusing that you discuss your topic in 2 forums. (or more?).
It's like one needs to read them all to know who said what.

The seals post did kind of get spread out.

It seems to have spanned:
a) the original thread in RO
b) some private email
c) the 'door seal calcs' thread in studiotips, where Rod responded to Paul's pics that Paul gave the URL to in RO, which are actually at
d) my msn group.
e) the '200mm Concrete slab db transmission loss' thread in studiotips (where Eric responded to the 'door seal calcs' thread about the thread in RO)

I tend to use RO when I'm looking for "This is the way we've always done it, and that won't work structurally."
I tend to use studiotips when I'm looking for "That won't work acoustically, these are the ways you could do it."
e.g. 'acoustic mat' below

It's not clear how your door is build and which rooms it connects.
Or I maybe miss one of your pictures.

I've tried to keep all the relevent pictures mentioned in each thread. I've even gone back and edited a couple of posts to update the links when pictures have been replaced.
All my pictures can currently be found at
http://groups.msn.com/BobGoldsHomeTheatre/shoebox.msnw
and to answer your question about the room to which it connects, please see the old drawing
http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=18

If there are neighbors those top 8 inches look not good.

yes.

Filling with expanded foam is by definition a bad idea with acoustics (hard and closed cells = no good for nothing. If it does something it's mostly negative).

Good point.
If I didn't have 6" of fiberglass under it I'd be really worried. The foam is there because there are holes in the floor. And holes have got to be bad. There's holes for the natural gas pipes going upstairs. There's holes around the ductwork. There's holes for wiring. There's holes for pipes. The duct pipes themselves have holes. There's no way to seal around all those shapes except with expanding foam. Over the wall to the equipment room is the same sort of thing -- pipes and round ducts. The only way to seal it is with expanding foam.

But I don't have to foam it from one end to the other. One possibility is to:
a) seal over the wall ('cork' it with foam),
b) seal the smaller floor holes with caulk and the larger floor holes with foam,
c) fill the rest with fiberglass, and
d) put two layers of drywall on the bottom of the joists there (55cm x 430cm of drywall).
e) duct tape around the duct pipes. (where I can reach them)

The acoustic mat in your floor is a bad idea here.

Oh.
I thought it would be ok because you said it was semi-good for floors (although the floor system in that thread was just concrete and tile), and I thought that subwoofers (17hz to 80hz, possibly louder than the usual 85db(C-slow), perhaps around 100db ) make an 'impact like' noise. I take it that something less springy is better here (more OSB wood).
Also I once read a home theater installation expert say that one shouldn't put drywall on a floor, one should always use Acoustik Mat instead.
I'm uncomfortable with the 'lead' idea -- to much of it can't be a good thing. Even if I seal it with something, I'm walking on it so the seal is going to break.

When designing a door: do you use a common frame? Seperate supports?

That's what I'm asking the forum. When I had a double wall design, I had a double frame design. The wall is still 8" thick, so there's still an opportunity for a double support design for the door.

If insulation is weak and you have weak spots, why not making it easy and use an additional layer or more on the inside?

That is exactly the sort of suggestion/advice that I'm looking for.
By 'layer' I assume you mean another 1/2" of drywall. An additional layer gives another 3db TL at 63hz.
Of course it's more work, and more money.
- To do that on the floor is easy.
- For the walls, RSIC shows no measured wall systems with three layers attached to the RSIC. Although structurally I presume that I could just use more RSIC hangers. I don't know what effect that would have TL wise, but I assume it's still good.
- To do that on the ceiling is expensive ($500 for ICW hangers, $100 joists, $100 channel, $150 drywall, $100 tape/screws/etc, +labor). I've already got the ceiling joists loaded as heavy as I dare. To put another layer on the ceiling would mean another set of joists and Kinetics ICW hangers. I had a look at my joist diagram, and I think I could do that. http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=45

I'll consider another layer.

I've drawn it with two layers of drywall at the top of the joists (near the floor) on battons. If I remove one of those layers I could put another layer on the ceiling without changing the joists/hangers. I think that would be better. (instead of 3-space-2, it's 2-space-3 -- and with the 3 layers on the inside it'll help the 'neighbors those top 8 inches' problem.

Let's not forget door suggestions please !

[Eric.Desart]

Hello Bob,

I just respond, since you're still waiting I see.
I have no time to go in this kind of detail (at least not now).

For this door, more important than the exact leave build-up:

You make your wall with those RSIC silencers, and your seiling with the Kinetics ones.
If you then use a common frame for both doors you destruct this system.

A door normally will behave different anyhow. For a door to work properly it must be stiff. This result in a flatter curve.
2 door leaves via a common frame is in fact no double leaf system anymore (a bid a hybrid).

So if you can make independent frames (depends on possibility for supports).
Make the door leaves somewhat heavier than the corresponding wall leaves.

You can do it with a common frame, but than the combined door must be a lot better to compensate for the flatter curve towards the higher frequencies (not that that matters that much).

Also do understand that calculating such a thing completely through is a complicated and time consuming business.

The expanded foam around the ducts through whatever.
I repeat once more: Do NOT use this foam, it will more provide structural transmission than sound insulation.

Eric

[Bob]

Thanks again Eric.

For a door to work properly it must be stiff. Make the door leaves somewhat heavier than the corresponding wall leaves.

Statistic noted. I can compute and comply.

So if you can make independent frames (depends on possibility for supports).

OK. New plan

Two four-sided wood 4x4 door Frames. Both sitting on 1/2 neoprine. The outer frame attached to the wall framing.

I can get some 3" 90-degree steel angle brackets and bolt them to the RSIC's hat channels on both sides of the door, and attach those to the inner wood 4x4 frame.
Angle brackets are rigidly bolted to the hat channel. A layer of 1/2 neoprine between the 4x4 and the angle bracket, and rubber washers between the screws and the angle bracket.
The bad news is that this sort of couples the inner gypsum wall to the floor. Which is a bit of a shame since the inner gypsum wall is nicely suspended from the floor in the current design.

Another possibility I dismissed for latteral (horizontal parallel to the wall) stability is to build the door frame taller than the door, and use the top part to make cross supports. With that I might not have to attach the frame to the inner walls. But that doesn't help when the door is open (perpendicular to the wall).

Which leads me to think that instead of angle brackets to the hat channels, a better way to go might be to put two pieces of steel (6"x8"x1/4") at the top of the two 4x4 door frames connecting them (6 screws each). With both of these steel mounted on neoprine, with rubber mounted screws, that should be strong enough to hold the door when it swings open, and provide isolation (the frame may wiggle like a drum), although it may move a bit.

To bridge the gap between the 4x4's the idea was to put a half inch of plywood on a half inch of neoprine, just glued in place, on all sides (left/right/top/bottom) between the doors.

You can do it with a common frame, but than the combined door must be a lot better to compensate for the flatter curve towards the higher frequencies (not that that matters that much).

Now I don't know what you're suggesting. Double frames or Common frames?

For a common frame what I was thinking was basically what Rod suggested in his diagram over at RO. Since RO is offline at the moment, I've uploaded his diagrams to http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=57
and
http://groups.msn.com/BobGoldsHomeTheat ... PhotoID=58

However it's not obvious to me how Rod's door jambs are supported. The diagram shows a space between the door jamb and the wall framing. I don't think those little wall facing plates (the picture frame around the door on both sides) even if screwed in to both the wall frame and the door jamb would provide structural strength for a heavy open door.

(I don't need to worry about wheelchair access. My basement is down a flight of curved stairs. No one with a wheelchair is ever getting down there.)

[Eric.Desart]

Bob,

I'm not going in competition.
I think Rod with his vast experience can explain his plans.

In general the cheapest way to get high insulation is using 2 doors with individual supports.
That makes the need for perfect sealing less important or sensitive.

If you couple your walls again with a double door it's logical that you weaken the principle at that point.

Probably for you the easiest way to go. And your individual doors can remain standard massive core doors (or whatever comparable).

If your wall are 2 gypsum layers it has no sence to have a door leave equal to 5 layers.

Eric.

PS: Bob I'm sorry. I really have a shortage in time and energy. And then I feel I'm getting nonchalant, more to finish it. So I should appreciate others jumping in.

[Rod Gervais]

However it's not obvious to me how Rod's door jambs are supported. The diagram shows a space between the door jamb and the wall framing. I don't think those little wall facing plates (the picture frame around the door on both sides) even if screwed in to both the wall frame and the door jamb would provide structural strength for a heavy open door.

(I don't need to worry about wheelchair access. My basement is down a flight of curved stairs. No one with a wheelchair is ever getting down there.)

Bob,

I apologize that the detail wasn't clearer - but when trying to focus on the isolation details - sometimes (IMHO) the added detail takes away the clarity.

Fastening of the door Jamb would be through the use of wooden shims to align the jambs - and then fastening with a 4" screw through the door jamb into the wall framing.

You should have shims in every location of a hinge - none are required at the door head - and a minimum of 3 on the latch side of the jamb.

Then fill the remaining air space between the door jamb and framing with rockwool - but make sure to not install it too tightly. You want a firm body of insulation - but if you pack it way to tightly you will lose isolation - not gain it. For the same reason - do not ever use expanding foams for those areas - they make bad isolators.

Recess the insulation slightly into the wall / jamb connection and seal with acoustic caulk.

Sweet - neat - and easy.

By the way - just for the record - i get tense about the thought of a single 2 x 4 wall supporting a 350 to 400 pound door in the long term - I do prefer the bridged door frame to tie the walls together - (IMHO) what little you lose in isolation value you gain long term by maintaining proper operation and alignment of the door seal assembly.

Rod

[Paul Woodlock]

By the way - just for the record - i get tense about the thought of a single 2 x 4 wall supporting a 350 to 400 pound door in the long term - I do prefer the bridged door frame to tie the walls together - (IMHO) what little you lose in isolation value you gain long term by maintaining proper operation and alignment of the door seal assembly.

Rod

It's making me a little tense as well :)

I'm quite a longway off building my inner room Door, but I'm also concerned about making a door frame stiff enough to hold a heavy door in a 2x4 stud wall structure. I'[m not worried about the door scraping on the floor, as it will be at least4 to 5 inches off the floor, but more worried about the structure flexing sligtly and misaligning the seals. I do intend to make the door frame out of 12 x 2 ( As outer door ), but any suggestions for stiffening up the frame would appreciated :)

Paul

[Eric.Desart]

By the way - just for the record - i get tense about the thought of a single 2 x 4 wall supporting a 350 to 400 pound door in the long term

It's making me a little tense as well :)

I'[m not worried about the door scraping on the floor, as it will be at least4 to 5 inches off the floor,....... :)

Paul

He Paul,
Are you sure this is meant as an acoustic door? Or is this a pass through for the cat?
Don't tell, you make the treshold sealing equal to the rest. I knew, just sounded strange.

I feel a 350 to 400 lb door as a contradiction in such a wall. If you close it to rough, your wall starts dancing.
I also think this should be senseless without realy professional sealing systems and accessories (conical compression and whatever).

I also think I never saw a standard sized single door leaf of 400 pounds for such a door type, even not the most professional ones with custom designed very heavy steel framing. And they are mostly designed for thick concrete/masonry walls.

Eric

[Rod Gervais]

Eric Desart wrote:

I feel a 350 to 400 lb door as a contradiction in such a wall. If you close it to rough, your wall starts dancing. I also think this should be senseless without realy professional sealing systems and accessories (conical compression and whatever).

I also think I never saw a standard sized single door leaf of 400 pounds for such a door type, even not the most professional ones with custom designed very heavy steel framing. And they are mostly designed for thick concrete/masonry walls.

Eric,

Take a peek then - and you can say you saw one...........

This is the control room in a studio i constructed a few years back - if you look to the left of the window on the right you can see the door - it weights just about 350 lbs.

It uses the 3 level gasketing system I show at RO - Zero Internation drop seals (surface mounted) very high quality closures - but just single doors at each opening through a double wall system.............

We have never had a complaint using this system............... However - on the right side of the control room the iso boothyou can see the window for serves as an air lock to the main room - and on the left there is a lobby - so these doors never directly connect from the control room to the main room.



Sincerely,

Rod

[Eric.Desart]

Hello Rod,

I take your word for it...

I've checked here:
For standard sized single doors the max weight I ever used is 315 lb for the leaf itself.

We tried/measured in our lab to increase TL by adding weight (designing heavier leafs). At 315 lb we were blocked in TL by other limiting factors.
We produced those doors (bit IAC like).

Regards
Eric

[Rod Gervais]

Eric,

I never tested the doors - but the construction is as follows:

Begin with a single 1 3/4" solid (particle core) door

Add

8 PSF Sheet Lead

add

3/4" Plywood

The sheet lead is glued to the door face and the pklywood is then glued to the lead - and fastened on the perimeter of the sheet at 4" O.C.

The Plywood terminates 3/4" inside the door edge..........

Thus the door seals agains a rubber seal - the plywood agains a 2nd rubber seal - and then again against a magnetic weatherstrip.

The drop seal hits both the sill assembly and presses out to seal against the side of the magnetic weatherstrip.

If all of this is constructed properly - with just the right fit - the door closure pulls the door and the magnetic strip holds it in a perfect seal - no need for any latching device. We do not have latches for the purpose of sound control on any of these doors.

We did install deadbolts for security purposes - but these are not in use when the rooms are occupied.

By the way - I hope you are having a great day today my friend............

Sincerely,

Rod

[Paul Woodlock]

By the way - just for the record - i get tense about the thought of a single 2 x 4 wall supporting a 350 to 400 pound door in the long term

It's making me a little tense as well :)

I'm not worried about the door scraping on the floor, as it will be at least4 to 5 inches off the floor,....... :)

Paul

He Paul,
Are you sure this is meant as an acoustic door? Or is this a pass through for the cat?

Don't tell, you make the treshold sealing equal to the rest. I knew, just sounded strange

LOL! - I only just got the Joke :)

Actually it's so my woman can slide a plate of food underneath without disturbing me :) :)

Seriously though, the reason is a difference in floor height from the house to the garage. The already constructed door swings about 7mm off the floor into the house.

If I make the Inner Room Door the same then one would hit one's head on the top of the frame when walking through them. So I figured a better way would be to have teh inner room door match the level of the outer door,and a step down to the studio floor level.

[b]I feel a 350 to 400 lb door as a contradiction in such a wall. If you close it to rough, your wall starts dancing.
I also think this should be senseless without realy professional sealing systems and accessories (conical compression and whatever).

I also think I never saw a standard sized single door leaf of 400 pounds for such a door type, even not the most professional ones with custom designed very heavy steel framing. And they are mostly designed for thick concrete/masonry walls.

Eric

Shaky walls. Reminds me of cheap soap operas :) Even the unsurpassable Fawlty Towers ( Flowery Twats ) has shaky walls - But in this case John Cleese is forgiven :)

I just did a rough calculation and my door weighs about 295lbs.

I think what I'll do for the inner room door is hang the 3 Layer bit first, and see what it's like. And then only stick the other 2 layers ( Layer = 18mm [ 3/4" ] MDF ) on if I really really need it.

I could always put a dampened door closer on it to prevent it from being slammed shut I suppose. And of course the stud wall arounf the door will be HEAVILY stiffened as much as is practical.

Cheers


Paul

[Eric.Desart]

Hi Rod,

Thanks for the explanation,

Paul,

Your whole studio has a rather special approach.
I responded a bit instinctive when I see a wall with 2 x 2 layers of gypsum, and then a door .....

Anyhow
Warm regards to both of you.

Eric