ah ha! another use for duct tape!:rotflm:
Soundproofing attached garage
- Thread starter Woodfish
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ah ha! another use for duct tape!:rotflm:
Check with a local commercial drywall supplier. If they sell metal studs & supplies they will have a product called 'sound reducing furring zees'. These are a sheet metal zee that has a large amount of the material removed in the middle of the zee to reduce noise transmission. It is applied perpendicular to the studs & the next layer of drywall is screwed to it. You could also add styrofoam insualtion or even old acoustical ceiling tiles between the zees to help out with sound.
How about the electronic way- sound inversion to neutralize the sound! :rotflm::rotflm:
Gentlemen,
I'm in the final stages of building a recording studio, so I hope I can speak with a bit of authority on what it takes to get isolation and sound proofing... whether I want to or not. :swoon:
Fully realizing that a wood shop is no where as demanding as recording studio in terms of isolation, you can effectively deal with the problem of sound transmission using many of the same principles.
It's important to understand what you're really up against before you can successfully attack the issue with a practical solution.
First, where air goes, so goes sound.
Second, high frequencies tend to move in straight lines, with low frequencies moving more in waves.
This makes high frequencies much easier to deal with than low frequencies. As an example, think about a train. You can hear the low rumble of a train as far as a mile away, but you can't often hear the high frequency squeal of the wheels much past a few hundred feet.
Low frequencies contain as much as 10 times the amount of energy as mid and high frequencies to sound the same apparent loudness. This is a characteristic of the human hearing that has given us the Fletcher-Munson curve.
Without getting too far into it, the practical outcome is fairly straight forward; This is done by absorbing the sound energy in the material, or by isolating the sound source through decoupling.
1. Mass is the single most effective way to reduce sound transmission, especially low frequencies.
2. By far, gypsum is the single most cost effective mass you can purchase as far as building materials.
3. Mass Loaded Vinyl (MLV) is a bit of voodoo magic in a huge number of applications. MLV is an attempt at increasing the overall mass of a barrier. While it does increase TL, it does so at a cost factor of approx 4:1 (up to as much as 12:1) of simply adding another layer of gypsum... of ANY thickness. MLV is installed in walls and ceilings, by rolling onto the surface and tacking it to the studs. MLV works by damping the vibration of the layer of surface directly in front of it. e.g. hitting a drum with a piece of material laying on it.
Green glue is an excellent product. I used over 12 cases in my studio, and my TL factors are yielding approximate STC ratings of nearly 84db. Without GG, my engineer estimates we would have been in the upper 70's db range.
To achieve those ratings, I added a LOT of mass in conjunction with the use of Green Glue... along with some pretty sophisticated engineering.
The air cavity within the stud bay of the exterior ( 2x8 ) stud wall has a layer of 5/8" gypsum between each stud. The gypsum is screwed to the exterior sheeting, then caulked along the perimeter and a secondary 1x2 cleat nailed to the stud, binding the gypsum edges to the stud.
The exterior walls were then filled with R-19 insulation, paper inward facing.
Rather than building as I have done, (Room within a Room), with a completely separate 2nd inner wall, ceiling and concrete floor, the next best thing is to face your stud walls with 3/4" sheet goods. I chose OSB over MDF due to cost and concern over potential moisture. Over that layer of OSB, I attached two layers of 5/8" gypsum with a layer of green glue between the gypsum.
The use of sheet goods is far superior to an isolation clip/hat or Z channel... both in terms of structural rigidity, (which creates a denser mass to airborne noise), but it is also cheaper and you cannot short out the channel by driving a screw too far, nor can you miss the channel and create a hole through which you will loose isolation.
You can use any relatively decent construction adhesive on the stud faces before applying the sheet goods. This adds additional structural rigidity and thus compounds the solid mass effect of adding the mass of the sheet good materials.
If you use a hat/Z channel with clips, to gain the TL/STC rating that are tested as per several of the national and international standards, you must use at least double the amount of resilient channel to achieve the same screw pattern of rigidity as outline by US Gypsum, the Canadian Building Standards and the BBC. This effectively triples the cost of using resilient channel solutions over conventional wood frame construction.
To further increase TL in the mid to low frequency range, stud spacing should be increased from 16" OC to 24" OC.
To reduce the effects of noise reverberation and it's associated flanking noise, one of the more common accepted principles used, is to place squares of fabric wrapped mineral wool, or Owens-Corning 703 rigid insulation on the finished surface of walls and ceilings.
If you want to get real propeller head, you can/should further reduce flanking noise, due to impact, by eliminating any connection of the floor to the rest of the structure. This is commonly done by using a concrete saw to cut through a concrete floor, the minimum distance you can achieve, along the entire perimeter of the room, to separate it from the rest of the floor.
There is a system of creating an isolated floor which is called "floating floor". This method is extremely tedious to attempt. It really does require the assistance of a qualified PE to attempt, due to the fact that this method is essentially loading a spring to a neutral floating condition.
Doors and windows are amazingly huge holes for sound to travel through. Again, where air goes, so goes sound.
My doors are just slightly overkill for a woodshop application, but they are exterior, solid core slabs, with 1/8" sheet lead, 2 layers of 3/4" plywood/MDF, with acoustic treatment of 1" OC 703 rigid insulation and 1x hardwood for the final surface.
All doors have an adjustable threshold, with a bottom sweep that rests on the threshold, and a 2nd bottom sweep attached to the plywood. All door casings are double stop plates with neoprene gasket seals on each interior stop, and resemble a step or bank vault.
Window's are individual challenges, but the principle of how much mass you need is the same as a door; the mass should be at least equal to, or greater, than the mass/sq ft of your wall... and not allowing any air passage along the door's perimeter.
To increase the TL even further, do NOT let your interior surfaces touch at the floor, ceiling or corners. Leave at least a 1/4" gap, and caulk each gap, followed by filling the gap with 1/2" backer rod, and caulk over that. The different layers should be installed in an alternating, stepped back pattern so that the gaps actually cross over each other.
I noticed there was a link to Sound Isolation Company as a supplier of Green Glue products. While GG is a fantastic product, I cannot express my utter frustration with their acoustic caulk sold under the name of SilenSeal. The product suffers from a 50% shrinkage, poor work ability and poor manufacturing quality control. I would recommend OSI's SC-175 Acoustic Caulk. It exhibits far less shrinkage, greater work ability and the clean up is a breeze.
For my little shop, I will be integrating many of the same principles I used in the studio. Namely, gypsum between the 2x4 studs and the ceiling joists, standard pink fluffy insulation, 3/4" OSB on the stud face, followed by 5/8" FR Gypsum. I'll caulk every single hole I can find to fill.
For my floors, since my building as completely wood framed, I'll put a layer of 3 lb/sq ft mineral wool, followed by 3/4" T&G OSB sub-flooring.
I'm in the final stages of building a recording studio, so I hope I can speak with a bit of authority on what it takes to get isolation and sound proofing... whether I want to or not. :swoon:
Fully realizing that a wood shop is no where as demanding as recording studio in terms of isolation, you can effectively deal with the problem of sound transmission using many of the same principles.
It's important to understand what you're really up against before you can successfully attack the issue with a practical solution.
First, where air goes, so goes sound.
Second, high frequencies tend to move in straight lines, with low frequencies moving more in waves.
This makes high frequencies much easier to deal with than low frequencies. As an example, think about a train. You can hear the low rumble of a train as far as a mile away, but you can't often hear the high frequency squeal of the wheels much past a few hundred feet.
Low frequencies contain as much as 10 times the amount of energy as mid and high frequencies to sound the same apparent loudness. This is a characteristic of the human hearing that has given us the Fletcher-Munson curve.
Without getting too far into it, the practical outcome is fairly straight forward; This is done by absorbing the sound energy in the material, or by isolating the sound source through decoupling.
1. Mass is the single most effective way to reduce sound transmission, especially low frequencies.
2. By far, gypsum is the single most cost effective mass you can purchase as far as building materials.
3. Mass Loaded Vinyl (MLV) is a bit of voodoo magic in a huge number of applications. MLV is an attempt at increasing the overall mass of a barrier. While it does increase TL, it does so at a cost factor of approx 4:1 (up to as much as 12:1) of simply adding another layer of gypsum... of ANY thickness. MLV is installed in walls and ceilings, by rolling onto the surface and tacking it to the studs. MLV works by damping the vibration of the layer of surface directly in front of it. e.g. hitting a drum with a piece of material laying on it.
MLV cannot be installed tightly stretched. If you do, it begins to act as a resonant drum head and actually REDUCES TL.
It is NOT known how tight to actually stretch MLV for optimal damping in a vertical or OH installation.
4. Resilient Channel (RC) is another often prescribed effective system of increasing TL through attempting isolation.It is NOT known how tight to actually stretch MLV for optimal damping in a vertical or OH installation.
Many other "channels" are often mistaken for the only product that is proven to reduce sound transmission - RC1.
Hat, Z and H channels are often hyped, but rarely work as effectively as RC1.
There are a number of additional clips that attach to the channel that provide further isolation... but again, this is additional cost for nominal gain.
In dealing with all this complex, often confusing and counter intuitive stuff, the one thing that often gets over looked is HVAC. If you have HVAC that enters your shop, that is shared with your home's HVAC system, you need to isolated the duct work so that sound does not travel as flanking noise, or as direct radiated energy back up the duct work. This is achieved through the installation of a plenum or baffel.Hat, Z and H channels are often hyped, but rarely work as effectively as RC1.
There are a number of additional clips that attach to the channel that provide further isolation... but again, this is additional cost for nominal gain.
Green glue is an excellent product. I used over 12 cases in my studio, and my TL factors are yielding approximate STC ratings of nearly 84db. Without GG, my engineer estimates we would have been in the upper 70's db range.
To achieve those ratings, I added a LOT of mass in conjunction with the use of Green Glue... along with some pretty sophisticated engineering.
The air cavity within the stud bay of the exterior ( 2x8 ) stud wall has a layer of 5/8" gypsum between each stud. The gypsum is screwed to the exterior sheeting, then caulked along the perimeter and a secondary 1x2 cleat nailed to the stud, binding the gypsum edges to the stud.
The exterior walls were then filled with R-19 insulation, paper inward facing.
Rather than building as I have done, (Room within a Room), with a completely separate 2nd inner wall, ceiling and concrete floor, the next best thing is to face your stud walls with 3/4" sheet goods. I chose OSB over MDF due to cost and concern over potential moisture. Over that layer of OSB, I attached two layers of 5/8" gypsum with a layer of green glue between the gypsum.
The use of sheet goods is far superior to an isolation clip/hat or Z channel... both in terms of structural rigidity, (which creates a denser mass to airborne noise), but it is also cheaper and you cannot short out the channel by driving a screw too far, nor can you miss the channel and create a hole through which you will loose isolation.
You can use any relatively decent construction adhesive on the stud faces before applying the sheet goods. This adds additional structural rigidity and thus compounds the solid mass effect of adding the mass of the sheet good materials.
If you use a hat/Z channel with clips, to gain the TL/STC rating that are tested as per several of the national and international standards, you must use at least double the amount of resilient channel to achieve the same screw pattern of rigidity as outline by US Gypsum, the Canadian Building Standards and the BBC. This effectively triples the cost of using resilient channel solutions over conventional wood frame construction.
To further increase TL in the mid to low frequency range, stud spacing should be increased from 16" OC to 24" OC.
To reduce the effects of noise reverberation and it's associated flanking noise, one of the more common accepted principles used, is to place squares of fabric wrapped mineral wool, or Owens-Corning 703 rigid insulation on the finished surface of walls and ceilings.
If you want to get real propeller head, you can/should further reduce flanking noise, due to impact, by eliminating any connection of the floor to the rest of the structure. This is commonly done by using a concrete saw to cut through a concrete floor, the minimum distance you can achieve, along the entire perimeter of the room, to separate it from the rest of the floor.
There is a system of creating an isolated floor which is called "floating floor". This method is extremely tedious to attempt. It really does require the assistance of a qualified PE to attempt, due to the fact that this method is essentially loading a spring to a neutral floating condition.
Doors and windows are amazingly huge holes for sound to travel through. Again, where air goes, so goes sound.
My doors are just slightly overkill for a woodshop application, but they are exterior, solid core slabs, with 1/8" sheet lead, 2 layers of 3/4" plywood/MDF, with acoustic treatment of 1" OC 703 rigid insulation and 1x hardwood for the final surface.
All doors have an adjustable threshold, with a bottom sweep that rests on the threshold, and a 2nd bottom sweep attached to the plywood. All door casings are double stop plates with neoprene gasket seals on each interior stop, and resemble a step or bank vault.
Window's are individual challenges, but the principle of how much mass you need is the same as a door; the mass should be at least equal to, or greater, than the mass/sq ft of your wall... and not allowing any air passage along the door's perimeter.
To increase the TL even further, do NOT let your interior surfaces touch at the floor, ceiling or corners. Leave at least a 1/4" gap, and caulk each gap, followed by filling the gap with 1/2" backer rod, and caulk over that. The different layers should be installed in an alternating, stepped back pattern so that the gaps actually cross over each other.
I noticed there was a link to Sound Isolation Company as a supplier of Green Glue products. While GG is a fantastic product, I cannot express my utter frustration with their acoustic caulk sold under the name of SilenSeal. The product suffers from a 50% shrinkage, poor work ability and poor manufacturing quality control. I would recommend OSI's SC-175 Acoustic Caulk. It exhibits far less shrinkage, greater work ability and the clean up is a breeze.
For my little shop, I will be integrating many of the same principles I used in the studio. Namely, gypsum between the 2x4 studs and the ceiling joists, standard pink fluffy insulation, 3/4" OSB on the stud face, followed by 5/8" FR Gypsum. I'll caulk every single hole I can find to fill.
For my floors, since my building as completely wood framed, I'll put a layer of 3 lb/sq ft mineral wool, followed by 3/4" T&G OSB sub-flooring.
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I apologize for the previous long winded post... but this IS a fairly complex issue, with a LOT of inadequate and often erroneous data presented.
Here are some links that are pretty much geared towards recording studios, but can easily be scaled back to the needs of a wood shop;
Here are some links that are pretty much geared towards recording studios, but can easily be scaled back to the needs of a wood shop;
- Speciality Products and Insulation
Products:
Mineral Wool, OC-703, OC-705 - plain and frk type, Fire Caulk
Comments:
National distributor with branches all over the US. Great pricing. 1" through 4" Mineral Wool and OC products. 24"x48" sheets up to 48"x96". Can purchase as many, or as few sheets as you want. - Sound Isolation Company
Products:
Green Glue - Tubes and buckets, SilenSeal Caulk
Comments:
Charlotte, NC based - Average Pricing, but usually have some sort of special. - Contractor Tool Supply
Products:
OSI SC-175 Acoustical Caulk
Comments:
Usually the best price on OSI products in the US. 
- John L. Sayers - Acoustics forum run by Australian studio designer; John L. Sayers
- Studio Tips - A superb acoustics forum. Not for the faint of heart. These guys get serious on physics.- Rod Gervais' book "Home Recording Studio - Build it Like A Pro" (Rod is the engineer who worked with me on the design of my studio)
- Philip Newell's book "Recording Studio Design"
Max, your post is the single most informative essay on sound control that I have ever read. Thanks MUCH for sharing your extraordinary knowledge on this topic.
One question - open cell spray foam... do you have any knoweldge about it's noise deadening properties? I'm thinking about spraying it in-between the studs on the interior walls of my generator room, and then using a double layer of gypsum with green glue on the interior of the walls.
I used it in-between the studs on the walls of an old farmhouse that is less than 30' away from a highway, and it did a remarkable job of deadening the noise that was previously coming in from outside.
Thanks again for the info.
Scott
One question - open cell spray foam... do you have any knoweldge about it's noise deadening properties? I'm thinking about spraying it in-between the studs on the interior walls of my generator room, and then using a double layer of gypsum with green glue on the interior of the walls.
I used it in-between the studs on the walls of an old farmhouse that is less than 30' away from a highway, and it did a remarkable job of deadening the noise that was previously coming in from outside.
Thanks again for the info.
Scott
I agree with Scott! Wow! Superb! That is one for the archives!!!
Thanx for the kudo's... but I'm really just a long winded ol' cuss.... 
The whole principle of mass being your friend is what you are after. The more effectively that you can create a solid mass is what you are trying to achieve... and hopefully within a reasonable budget. (oof... that's the one is what kills ya!)
As far as open cell spray foams... There's a bit of debate on it.
Many of the "acoustic foams" that actually work, are open cell foam. Technically they do work... but the amount of low frequency absorption is actually so little that it doesn't work in terms of practical numbers. Closed cell foams are worthless.
Again, this is in reference to open cell foam use as an acoustic treatment, and does not have a thing to do in terms of the spray foams used in the construction trades.
The little data I have seen in regards to the spray foams is that the closed cell seems to resemble it's cousin, bedding foam. e.g. decent thermal properties but less significant at reducing LF transmissions than a piece of paper.
The spray open cell foam's are fairly new technology that haven't yet been sent to places like Riverbank for testing. (If they have, no one has been discussing them.) However, IMVHO, I would guess that the open cell foams are going to work fairly well at both thermal and sound absorption... probably far better than they do as a standard acoustic treatment.
The fact that they are creating more air cells in a tighter confined space, e.g. stud bay, that they are actually creating a much more compressed "spring" and thus, would absorb more sound energy.
I remember you taking me through the farmhouse, and yes, it was darn quiet up there! So, I wouldn't be afraid to try it at all.
I would consider using 1/2"-ish plywood or even 3/4" chip board (non cert OSB) and green glue with one layer of 5/8" gypsum for your gennie room with regular pink fluffy... IF you decide to not use the open cell spray. Again, the rigidity is a compounding factor to the mass equation. The more you can tie the whole structure into a single mass, the better.
It's not like you couldn't go back and add more gypsum, but I'd probably try the open cell spray and a single layer of either wooden sheet good or gypsum and see what you get.
You could also try getting your compressor isolated by floating it on a suspension pad. (Floating a single tool is a LOT easier than an entire room.)
The whole principle of mass being your friend is what you are after. The more effectively that you can create a solid mass is what you are trying to achieve... and hopefully within a reasonable budget. (oof... that's the one is what kills ya!)
As far as open cell spray foams... There's a bit of debate on it.
Many of the "acoustic foams" that actually work, are open cell foam. Technically they do work... but the amount of low frequency absorption is actually so little that it doesn't work in terms of practical numbers. Closed cell foams are worthless.
Again, this is in reference to open cell foam use as an acoustic treatment, and does not have a thing to do in terms of the spray foams used in the construction trades.
The little data I have seen in regards to the spray foams is that the closed cell seems to resemble it's cousin, bedding foam. e.g. decent thermal properties but less significant at reducing LF transmissions than a piece of paper.
The spray open cell foam's are fairly new technology that haven't yet been sent to places like Riverbank for testing. (If they have, no one has been discussing them.) However, IMVHO, I would guess that the open cell foams are going to work fairly well at both thermal and sound absorption... probably far better than they do as a standard acoustic treatment.
The fact that they are creating more air cells in a tighter confined space, e.g. stud bay, that they are actually creating a much more compressed "spring" and thus, would absorb more sound energy.
I remember you taking me through the farmhouse, and yes, it was darn quiet up there! So, I wouldn't be afraid to try it at all.
I would consider using 1/2"-ish plywood or even 3/4" chip board (non cert OSB) and green glue with one layer of 5/8" gypsum for your gennie room with regular pink fluffy... IF you decide to not use the open cell spray. Again, the rigidity is a compounding factor to the mass equation. The more you can tie the whole structure into a single mass, the better.
It's not like you couldn't go back and add more gypsum, but I'd probably try the open cell spray and a single layer of either wooden sheet good or gypsum and see what you get.
You could also try getting your compressor isolated by floating it on a suspension pad. (Floating a single tool is a LOT easier than an entire room.)
Another cheap guy question - is it even worthwhile to consider draping sound blankets between the machine and living area? They are really cheap - here is one for $20:
http://www.markertek.com/Acoustic-Materials/Sound-Blankets/VAN-PAD-BLACK.xhtml
I know they don't sound proof a room, but can you strategically place one or two and have much impact on the sound transmitted in a particular direction? I have a few operations that are borderline and just a little more dampening would make them doable at a lot more hours.
http://www.markertek.com/Acoustic-Materials/Sound-Blankets/VAN-PAD-BLACK.xhtml
I know they don't sound proof a room, but can you strategically place one or two and have much impact on the sound transmitted in a particular direction? I have a few operations that are borderline and just a little more dampening would make them doable at a lot more hours.
Sure... you can use those. But here's the skinny on the real deal... just use a $6 packing blanket from U-Haul or get a box of em' from U-Line. They're essentially the same thing but a LOT cheaper... even if you have to double up on em.
Other "thingy" we use in the recording biz, are called gobo's. They're pretty darn effective, and reasonably cheap to make. (granted you can purdy em' up as much as you want)
The gobo's I'll be making will be 3'x5';
1) fabric wrapped OC 703
2) 5/8" gypsum
3) 3/4" OSB/MDF or Ply
4) 1/2" Hardie Backer
5) 3/4" OSB/MDF or Ply
6) 5/8" gypsum
7) 5/8" gypsum
Other than the 703, wrapping the insulation in a burlap and putting a band of hardwood around the whole edge, you can make these for little money. Mine will be mostly made from scraps I have left over from the construction. In a studio, we generally put casters under a gobo so you can easily move em around, but in a shop, I would think you could leave em' stationary and make a angled leg for a single unit, or tie a couple of em' together with a couple of tie bars made from anything you wanted... just so long as they're stable.
1/2" Hardie Backer is cheap... I think about $7-8/sheet the last time I looked. 5/8" gypsum is what... less than $9/sheet?
Mineral wool is dirt cheap compared to OC-703, but you could use something like a packing blanket or not even use anything absorbent on one side. We generally use something absorbent on one side to minimize sound being reflected over the gobo... but you could omit the absorption to start and see how well that dampens the sound.
Thanx for the kudo's... but I'm really just a long winded ol' cuss....
The whole principle of mass being your friend is what you are after. The more effectively that you can create a solid mass is what you are trying to achieve... and hopefully within a reasonable budget. (oof... that's the one is what kills ya!)
As far as open cell spray foams... There's a bit of debate on it.
Many of the "acoustic foams" that actually work, are open cell foam. Technically they do work... but the amount of low frequency absorption is actually so little that it doesn't work in terms of practical numbers. Closed cell foams are worthless.
Again, this is in reference to open cell foam use as an acoustic treatment, and does not have a thing to do in terms of the spray foams used in the construction trades.
The little data I have seen in regards to the spray foams is that the closed cell seems to resemble it's cousin, bedding foam. e.g. decent thermal properties but less significant at reducing LF transmissions than a piece of paper.
The spray open cell foam's are fairly new technology that haven't yet been sent to places like Riverbank for testing. (If they have, no one has been discussing them.) However, IMVHO, I would guess that the open cell foams are going to work fairly well at both thermal and sound absorption... probably far better than they do as a standard acoustic treatment.
The fact that they are creating more air cells in a tighter confined space, e.g. stud bay, that they are actually creating a much more compressed "spring" and thus, would absorb more sound energy.
I remember you taking me through the farmhouse, and yes, it was darn quiet up there! So, I wouldn't be afraid to try it at all.
I would consider using 1/2"-ish plywood or even 3/4" chip board (non cert OSB) and green glue with one layer of 5/8" gypsum for your gennie room with regular pink fluffy... IF you decide to not use the open cell spray. Again, the rigidity is a compounding factor to the mass equation. The more you can tie the whole structure into a single mass, the better.
It's not like you couldn't go back and add more gypsum, but I'd probably try the open cell spray and a single layer of either wooden sheet good or gypsum and see what you get.
You could also try getting your compressor isolated by floating it on a suspension pad. (Floating a single tool is a LOT easier than an entire room.)
Max, that's good feedback - thx. I already have the generator skid sitting on rubber mats and 2 x 4's above the slab, so hopefull that will help isolate the vibration. The engine fan also pulls air out of the room and forces it outside through the radiator, and I think that this may help pull some of the sound outside.
My biggest concern is the door to the room. I have a double door (interior), and I doubt that it will do much in terms of noise deadening. I was thinking about installing a liftable baffle on the generator room side of the door (probably on a counterweighted pulley system suspended from the ceiling for easy removal). After reading your comments on the "gobo's", I may opt to copy something like that for baffle.
Scott,
You'd actually be surprised at just how much deadening you can probably get from your doors, just by installing air tight weather stripping around them. Foam weather stripping is probably adequate, but a good soft neoprene will out last the foam stuff by years.
Even tacking some narrow 1x to the existing door stops to make a second seal will make an improvement.
If the doors are hollow core, to can apply some contact cement to a sheet of 3/4" BC, OSB or MDF and attach it to the door along the edges. I'd recommend a decent sheet rock screw. Just make this plate 3/4" shorter at the top and on the sides. Then you can step back the 2nd door stop by a bit over 3/4" to accommodate your neoprene seal.
Make sense, or am I just being mildly incoherent?
You'd actually be surprised at just how much deadening you can probably get from your doors, just by installing air tight weather stripping around them. Foam weather stripping is probably adequate, but a good soft neoprene will out last the foam stuff by years.
Even tacking some narrow 1x to the existing door stops to make a second seal will make an improvement.
If the doors are hollow core, to can apply some contact cement to a sheet of 3/4" BC, OSB or MDF and attach it to the door along the edges. I'd recommend a decent sheet rock screw. Just make this plate 3/4" shorter at the top and on the sides. Then you can step back the 2nd door stop by a bit over 3/4" to accommodate your neoprene seal.
Make sense, or am I just being mildly incoherent?
Max, that makes sense - thanks. I actually have some 4 x 8 sheets of a special sound deadening material, so I may screw it on the back of the doors and then attach some sheetrock to the inside of it for two layers (as well as fireproofing - not a bad idea for a generator room...)
Let me echo Scott's comments. This has been incredibly helpful, especially with all the practical advice on caulking, gaps, variations etc. The info I've come across so far generally assumes you're starting from scratch (as opposed to modifying an existing structure built the conventional way) and/ or suggests material that's hard to obtain or expensive. Drywall, OSB, blankets, weatherstripping and fiberglass insulation are items I can work with! I'm not shooting for total silence, just bringing down a 90dB machine to around 70dB. I think I can do that now.
:icon_thum :icon_thum :icon_thum
Bas,
The thing that amazes me is that the world is getting so specialized in so many "industries" that its almost like we're loosing out on good ol' common sense when it comes to products. I've seen regular speaker wires sell for $100/ft because it was claimed to have some kind of specially reduced oxygen content and "certification"... regular power cords that cost $300/each... all kinds of silliness. Most of it snake oil, too.
We have all this information we're able to gather, collect and organize, but then it gets tough to put it all together....
(Believe me, I know from first hand experience!)
The basic principle's of mass and decoupling are so obvious, that they become obscured in the midst of all the specialized products out there.
e.g. Resilient Channel and isolation clips being the biggest exception. The thing that most "acoustic professsional's" fail to realize is that they are supposed to be used under specific circumstances; metal studs and joists.
They can be used with wood studs and still be effective, but not nearly as effective as the more cost effective approach as adding a layer of sheet goods.
I've uploaded a couple of the pdf's from my set of prints about the doors...
http://www.dmmobile.com/blog/wp-content/uploads/2009/10/a-8.pdf
http://www.dmmobile.com/blog/wp-content/uploads/2009/10/a-84.pdf
This next pdf explains the "stepped" corners...
http://www.dmmobile.com/blog/wp-content/uploads/2009/10/a-92.pdf
The thing that amazes me is that the world is getting so specialized in so many "industries" that its almost like we're loosing out on good ol' common sense when it comes to products. I've seen regular speaker wires sell for $100/ft because it was claimed to have some kind of specially reduced oxygen content and "certification"... regular power cords that cost $300/each... all kinds of silliness. Most of it snake oil, too.
We have all this information we're able to gather, collect and organize, but then it gets tough to put it all together....
(Believe me, I know from first hand experience!)
The basic principle's of mass and decoupling are so obvious, that they become obscured in the midst of all the specialized products out there.
e.g. Resilient Channel and isolation clips being the biggest exception. The thing that most "acoustic professsional's" fail to realize is that they are supposed to be used under specific circumstances; metal studs and joists.
They can be used with wood studs and still be effective, but not nearly as effective as the more cost effective approach as adding a layer of sheet goods.
I've uploaded a couple of the pdf's from my set of prints about the doors...
http://www.dmmobile.com/blog/wp-content/uploads/2009/10/a-8.pdf
http://www.dmmobile.com/blog/wp-content/uploads/2009/10/a-84.pdf
This next pdf explains the "stepped" corners...
http://www.dmmobile.com/blog/wp-content/uploads/2009/10/a-92.pdf
Tons of good information here and lots of varied approaches. In my own experience building a closet for noise control from my compressor and DC I found out the hard way one has to follow a rule that Max pointed out:
First, where air goes, so goes sound.
When my closet was finished I had a gap of less than 1/8" at the top of one wall that to my surprise allowed a lot of sound to escape. An application of 3/4" thick molding eliminated the problem. :wsmile:
First, where air goes, so goes sound.
When my closet was finished I had a gap of less than 1/8" at the top of one wall that to my surprise allowed a lot of sound to escape. An application of 3/4" thick molding eliminated the problem. :wsmile:
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