Temporary "FAQ"- (was "Complete Section")

How thick should my walls be, should I float my floors (and if so, how), why is two leaf mass-air-mass design important, etc.

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cfuehrer
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Post by cfuehrer »

COOL! Thanks so much.
Peace,

Carl Fuehrer
Pulsar Audio Lab
http://www.pulsaraudiolab.com
knightfly
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Post by knightfly »

Thought I'd ressurect this thread rather than write everything twice, had a Q from Fitz over on HR about ceilings and hadn't noticed much on that area in this thread -

Keep in mind that (hopefully) our minds are not stagnant pools of amorphous gelatin with no noticeable shifts in patterns, shapes or awareness, so a couple of things I bring up here may slightly contradict earlier statements - don't panic, nothing major, just means I'm not dead yet (rumors have been maliciously exaggerated) :?

Oh, yeah, ceilings...

Here is part of Rick's post from HR (sorry Rick, getting tired of spewing out the same things in multiple places and wanted to make sure this got included in this particular thread, since it's fast becoming the "FAQ" I've yet to write...

"Say, on CEILINGS, with 3 layers of Gypbd, would you fasten the first layer with minimal screws, as the next layers screws would also help fasten the previous layers? Alternating joints? Caulk each layers joints? How bout RC, will it hold the weight of 3 layers? Seems like the weight would negate the vibration capability of the RC flange, by pulling down on it. Would you float the ceiling gypbd panels between walls, or hang the ceiling gypbd first, so the wall gypbd helps supports the ceiling panels at the wall/ceiling intersection, like normal construction? Normal construction uses no blkng between joists at the wall intersection perpendicular to the joists. How about studio joists? Do you block them?"

In order - On a first layer, it would be tempting to use fewer screws (all of this next is assuming you're using RC) but if you do, there's a possibility that the first layer could sag between screws, leaving a gap that would be hard to "suck up" with the screws for the second layer. Plus, because we ARE using RC, there's almost no reason NOT to use as many screws as it takes to get good holding. Remember, this is a ceiling (gravity, pain, etc.)

Alternating joints and full caulking are a given ANYWHERE -

RC and weight - Same as a car's springs - if you were designing a car the size of a Cadillac but only had springs for a Volkswagen, you'd have to use MORE springs, right? Same with RC - What you're trying for is a correct spring RATE, so if you want three FULL thickness layers on RC that's designed for TWO, put the RC on closer spacing to compensate. The Dietrich RC Deluxe, for example, will hold two full layers no problem. If you want three, cut the spacing down from 24" to 16" centers and you're good to go. If you were to use TWO layers of 5/8" rock with a thinner, 1/4" or 3/8" center layer (about the same performance as using sheet blok between two 5/8" but MUCH cheaper) then I'd split the difference and use 20" centers for the RC.

Floating ceiling layers between walls - For most situations, this would be my first choice. Gives more vibration isolation between walls and ceiling. There are so many scenarios here, depending on what is being built where and in what order, that it's nearly impossible to describe each situation and prescribe for it. Remember, the goal (whether we achieve it or not) is TWO mass centers separated by ONE air space, in any direction you want to look (floor, ceiling, walls, doors, windows...)

Blocking between ceiling joists, where possible, should be done as a continuous part of the OUTER leaf of the ceiling, which (usually) will include the above floor's subfloor mass. This blocking should be fortified with a couple layers of gypsum and sealed. Where walls that are parallel to ceiling joists meet the ceiling, an extra joist can be added to line up with the outer wall leaf. This should also have a couple layers of wallboard added because wood isn't as good for isolation as gypsum.

I hope this answers some questions - here's an example, to clarify -
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...
knightfly
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Post by knightfly »

And here's an example of how to achieve part of the goal -

Note the new drawing, this is just one way to achieve isolation of framing to avoid flanking thru wall into ceiling frame -
Last edited by knightfly on Thu Dec 04, 2003 5:52 am, edited 3 times in total.
knightfly
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Post by knightfly »

With a detail of the DIY sway bracket -
Last edited by knightfly on Sat Nov 29, 2003 9:30 pm, edited 1 time in total.
rsg
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Post by rsg »

Hey Steve,

I've just gotten into this whole building studios thing quite recently. I've already learnt a fair amount after reading what you and a lot of other people have been saying here, and it's helped me quite a bit.

Anyways, I'd like to ask if you could help me by giving me some tips on soundproofing a room for band practices and basic recordings.

My building has 6 flats in it, all attached side by side. Each apartment has 3 floors, and each apartment is separated by a wall. The top floor has 2 bedrooms and a bathroom, middle floor has a lounge, kitchen and a bathroom and the bottom floor a a spare room and a garage. Now I'd like to convert the bottom floor spare room into a sound proof room.

The walls are concrete and 24 cm thick, as is the ceiling. I want to build a wall to close off the spare room downstairs and need some advice on that. The width of the room is 4m and length is 5m. I'd also like to know what I must then add to the rest of the walls inside the room to keep the noise to a minimum. There's also a window, and I would like to seal it off, how? How to I attach the RC to the wall and the dry wall/gypsum and how many layers should I use? I'm a bit confused, but what are the differences between gypsum and drywall? Or is it the same thing? What would you reccomend? What exaclty is rockwool? I read around but didn't find any good explanations, maybe I just missed them. What should I use for the ceiling? We only have to worry about the 2 walls already there and the third one I want to build, because the one at the end of the room is 3/4 underground.

How this works is you enter the house via the middle floor, and to get to the back garden, there is a slanted drive way on the side of the flats. So the ground level in front of the house is high than the back, and thats why the room is 3/4 below the ground from the front. The room is however level.

I've got the feeling I've just written the biggest load of crap and you won't understand, but I hope you do. Please let me know if you can offer me any advice and if you understand what I wrote.

Rafal
knightfly
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Post by knightfly »

Rafal, I think I've sorta got what you mean, but it would be much easier if you could post a drawing - if you're on a mac, I'm sorry I asked - I still can't believe Apple can't even include a basic drawing program with their operating system. On the PC, you've at least got Paint, which I use for quick drawings - in fact, the last two drawings in this thread were done just on Paint.

Anyway, if possible could you draw a basic floorplan of the spare room and garage, and label which walls are concrete, etc - also, what is the total available ceiling height? Any and all openings, and where they go -

24 cm concrete walls? That alone should get you about 60 dB of STC, with 45 dB clear down to 50 hZ - adding a single layer of 12.5 mm wallboard on a separate stud frame inside your walls would improve the isolation to around 70 dB at 500 hZ, and still around 45 dB at low end. The advantage of doing only ONE layer of wallboard is interior sound. This inner wall will act like a bunch of panel bass traps, saving you the trouble of building as many as you normally would have to.

Yes, gypboard, gypsum wallboard, drywall, sheet rock, gypsum wall panel, gyp rock, plasterboard, all are different names used in different locales for exactly the same product - compressed gypsum with paper backing on both sides.

Finally, I need some kind of idea about material costs in your area - England has really high prices for most building materials, but masonry seems to be cheaper - Indonesia; gypsum expensive, bricks almost free - The main products I need an idea of (at least RELATIVE) cost on, are gypsum wallboard, framing lumber, lightweight STEEL framing, brick, concrete block, and heavy flooring plywood -

Finally reached a point where I can't even think, so I'm off to bed - see what you can gather, search the forum for "window plug", there's a thread by Laptoppop somewhere in the construction forum - I'll check back later... Steve
rsg
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Post by rsg »

Thanks for getting back to me.

Anyways, I did a drawing, not to great but I hope it works. The measurements for the window are 2m wide * 62cm high. The ceiling is 2,51m high all round and the air hole measurements are 18.5cm * 10cm.
The air holes lead outside, so definitely need to do something about that.

I'm not entirely sure the wall is concrete, it may be brick, but it is definitely 24cm thick. The walls in the drawing are concrete/brick all round and in between the spare room and garage, but the wall between the spare room/garage doesn't really matter because there will be a wall before it, at least I don't think it matters.

Prices here change all the time and I don't actually know what they are, but they are relatively cheap for materials here and I'm not too concerned about price, unless you really need to know, then I'll find out. I think that prices here will be similair to the US. I'm just looking for the best option you could offer me to bring the room to about 70 - 75+ stc, if thats reasonable. Is there a way to check the STC? I know the wall should already be quite sound proof, but I can here things like doors and tv's next door, faintly, but they are there, meaning that I will make a hell of a noise if I don't do some sound proofing.

I was thinking of doing more than one wallboard, because another reason I don't want people to hear on the outside is they'll steal my stuff when they get a chance for sure. Hope thats enough info for now.

Few more questions, how do I attach rc's to to wall and the the board, and is that how you do it? What exactly is caulk and what does it look like.
Do you think I'll still have to do some work on the floor? At the moment it's just 2 carpets and a cement floor.

Thanks very much for any help you can offer me. I appreciate it a lot.

Rafal
knightfly
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Post by knightfly »

Rafal, sorry your question got lost - it would have been better if you had posted your own, separate question. When questions get tacked onto other threads, it's much harder to keep track.

Have you had a chance to read the other three pages of this thread? It answers quite a few questions you've asked here. I'm off to bed for now, been a rough week and it's not over yet, working 12-hour night shifts next two nights. I'll try to remember this is here, but it would be better if you'd start your own thread so it doesn't get lost... Steve
wildplum
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Post by wildplum »

I get the impression from the section knightfly posted above that if you build two adjacent walls, say between a control room and a live room, the tops and bottom sill plates most completely enclose the space between the walls- the space between the sills (needed to keep them from transmitting vibrations) would be filled with some kind of resilient material, such as neopreme. I am not sure I am making sense- and this is one point I am very unclear about.
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knightfly
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Post by knightfly »

If you get anxious for clarification, you could post a drawing of what you think the wall construction should be - otherwise, I'm working on re-doing the earlier drawing into separate drawings for different situations, with better labeling for clarity. This may take a few days, as I'm continually falling further behind on the ol' "honey-dew" list, but it will happen eventually... Steve
jazzmania
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Post by jazzmania »

Steve,

Your descriptions are always invaluable. I just have one question on the spacing of RC Deluxe on the ceiling. You (and I think Rod) have specified 24" if you're hanging 2 sheets of 5/8" Firecode. Makes sense to me, but I was just wondering where that spec comes from, as I asked Dietrich (current parent company of RC Deluxe) that very same question, and the only tested specs they could give me were all 16" OC. Can you point me to a source of your 24" recommendation? If it's your own experience, that's fine.

Lee
knightfly
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Post by knightfly »

You may be ahead of both Rod and me on that one - I was going by USG's recommendations for their RC-1, which Dietrich's RC Deluxe is supposedly a carbon copy of - I know Dietrich doesn't recommend using their lighter RC for ceilings, but had not seen a spec for 16" centers using only two layers.

RC is essentially a spring, and springs only work well (or at all) if they are properly loaded. Usually, this means somewhere between 25% and 75% of their range of motion, sometimes less. That's why I recommended closer spacing for more layers.

However, if Dietrich is recommending 16" centers for only two layers of 5/8 wallboard on ceilings, it's their product - I would have to assume that maybe their RC isn't quite as heavy as the original, or else they're just more "Product Liability" oriented now.

Such being the case, I'd stick to the manufacturer's recommendations, and if you want more layers adjust the centers closer to compensate.

That would put centers at about 11" for three full layers of 5/8 wallboard - or just over 13" centers for my favorite combo, 5/8", 3/8", 1/2" on RC. So much for "standards", like 16" and 24"... Steve
cfuehrer
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Post by cfuehrer »

I wanted to get some idea of how my ceilings will be. I am building a room within a room and the ceiling in the room is too high and made of concrete so I can't suspend the individual ceilings in each room. How would they be best isolated from the walls since I take it they would have to rest on top of the walls.
Peace,

Carl Fuehrer
Pulsar Audio Lab
http://www.pulsaraudiolab.com
knightfly
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Post by knightfly »

You could do it this way -
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Post by knightfly »

Wild Plum, if you're still around have you checked this thread? It gives quite a bit of info on wall do's and don'ts -

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=598

If you've already been through that thread and need more clarification, just say so... Steve
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