I’m about to build a new studio control room from the ground up. Conventional construction: wood frame, drywall, and a flat, almost horizontal roof. One room - about 15 x 25 feet with an 11’ ceiling.
In an effort to keep our costs down, the idea was to have exposed ceiling joists (2x12” beams with 16" centers) ... and have the exposed fiberglass insulation absorb sound, (possibly stapled up by the paper backing) and basically, in a way, make the ceiling 'disappear' - acoustically speaking (more or less)
However I'm very hesitant to have any chance of any exposed fiberglass fibers... due to possible long term health concerns. :shock:
Any clever ideas about how to achieve the necessary R30 insulation between the exposed 2x12” ceiling joists… and also have that same insulation absorb sound? (and look decent too)
Thanks!
:)
get R30 + sound absorption w/ 2x12” exposed ceiling joists?
Originally posted at johnlsayers.com, topic 9954.
Hi there,
One question and one answer for you:
Question: in an attempt to picture your situation, I got confused on the build's layout. Is the following interpretation correct?
You're planning a dedicated control room, not a mixed control/live room.
Control room dimensions
_H: 11 feet
_L: 25 feet
_W: 15 feet
Ceiling beams
_H: 12 inches
_L: 25 feet
_W: 2 inches
Beams will be spaced 16 inches apart.
Presuming this is correct, on to your fiberglass placement. The beams will be 'naked'. The 16 inches in between the beams will be filled up with absorptive material (like fiberglass). No other materials (except those to keep out the weather conditions of course :D ) will be used to construct the ceiling.
Is this how you'd pictured it?
Answer: About the health hazard of fiberglass, there's been some discussion on that topic on the forum a while back. I think the conclusion was: "it's not proven to be harmful once it's installed and not moved again. Wear protection (mask, long sleeves, gloves,...) while installing it, seal it off with some material (fiber, gypsum,...), vacuum your construction site afterwards. Whatever you do, don't eat it."
Cheers,
Sigert
Heya Sigert I will occasionally use the room for recording in - soloists, small ensembles.... but it will mainly be a mix room. The joists will run the short way across the room - so the roof joists will be approx 15' long.... yes - 2" x 12" beams, on edge. The plan was to NOT seal in the fiberglass behind any fiber, gypsum... so it would be open to absorb sound. yes - naked joists. If you look up in the finished room, you'd see the exposed 2" edges of the roof joists... and whatever material is stuffed between the joists to provide the R30 insulation that the city requires... thanks for any ideas as to what to use between the joists for both R30 and sound absorption. :)Hi there, One question and one answer for you: Question: in an attempt to picture your situation, I got confused on the build's layout. Is the following interpretation correct? You're planning a dedicated control room, not a mixed control/live room. Control room dimensions _H: 11 feet _L: 25 feet _W: 15 feet Ceiling beams _H: 12 inches _L: 25 feet _W: 2 inches Beams will be spaced 16 inches apart. Presuming this is correct, on to your fiberglass placement. The beams will be 'naked'. The 16 inches in between the beams will be filled up with absorptive material (like fiberglass). No other materials (except those to keep out the weather conditions of course :D ) will be used to construct the ceiling. Is this how you'd pictured it? Answer: About the health hazard of fiberglass, there's been some discussion on that topic on the forum a while back. I think the conclusion was: "it's not proven to be harmful once it's installed and not moved again. Wear protection (mask, long sleeves, gloves,...) while installing it, seal it off with some material (fiber, gypsum,...), vacuum your construction site afterwards. Whatever you do, don't eat it." Cheers, Sigert
I'm lacking expertise to offer answers, but 2 concerns do come to mind:
1) Despite of it being named "insulation", for all I know, insulation material by itself is not the way to go if one wants to significantly decrease sound transmission from one space to another. Unless it's used in combination with a more extensive construction, the only thing a porous absorptive material has to offer is control over your sound spectrum. Yes, it does 'eat up' sound energy, but not to the extent of it being able to keep the peace between you and your neighbours.
So, naked insulation between joists, in combination with standard roofing to keep out the rain, will not significantly reduce sound transmission.
2) I'm concerned about the joists not being 'in line' with the main sound direction (which is probably lengthwise). As I see it, it might be harder to predict reflection patterns and deal with in-room acoustics. But then again, I may be threatening pigeons with a bazooka.
Cheers,
Sigert
1) i'm keen to absorb some sound - but only for the purposes of the sonics inside the room. I am not concerned with trying to keep sound from leaving the room 2) the joists being across the main sound direction should provide some diffusion. That is the plan. 8)I'm lacking expertise to offer answers, but 2 concerns do come to mind: 1) Despite of it being named "insulation", for all I know, insulation material by itself is not the way to go if one wants to significantly decrease sound transmission from one space to another. Unless it's used in combination with a more extensive construction, the only thing a porous absorptive material has to offer is control over your sound spectrum. Yes, it does 'eat up' sound energy, but not to the extent of it being able to keep the peace between you and your neighbours. So, naked insulation between joists, in combination with standard roofing to keep out the rain, will not significantly reduce sound transmission. 2) I'm concerned about the joists not being 'in line' with the main sound direction (which is probably lengthwise). As I see it, it might be harder to predict reflection patterns and deal with in-room acoustics. But then again, I may be threatening pigeons with a bazooka. Cheers, Sigert
Hi there, not sure if this is the same question/poster from another forum, but you may consider Ultratouch cotton if you are worried about the health issues of fiberglass (though in one of the stickies in this forum, there is an article discrediting health risks associated with fiberglass and rockwool. Maybe so but the stuff is still harsh to work with imho).
Also, the joists will not create diffusion. They may add a small amount of reflection, but diffusion doesn't just happen randomly, it requires a specific design with specific goals as to what happens with reflections. Yes there is math involved. :-)
I disagree. For example - bookshelves are AWESOME random sound diffusers. :wink: seriously.......Also, the joists will not create diffusion. They may add a small amount of reflection, but diffusion doesn't just happen randomly, it requires a specific design with specific goals as to what happens with reflections. Yes there is math involved. :-)
anyone else wanna chime in?
8)
About bookshelf diffusers and diffusers in general:
Without going into the math of it, the frequency range in which a diffuser shows effect depends on mainly 2 factors:
1) maximum depth of the construction
2) number of variations in depth
These two factors make that a good, broadband diffuser will take up much room, as it has to be a deep construction with as many variations as possible. This makes at least one reason diffusers are not first choice within small space acoustic treatments. There are better space/effective measures that can be taken.
The bookshelf diffuser is quite an appealing idea, and it does provide improvement to some extent. it's good in terms of variation in depth, thus being good at diffusing the frequencies effected by it. It's not very deep though, so the frequency range it will affect is rather small.
For all I know though, it 'll only be worth the trouble/space in rooms of considerable size that were already quite good sounding before the bookshelves were placed.
To act as a diffuser, your beams will be:
1) too far apart
2) lacking variation in depth
Calculating the correct distance between variations in depth will bring you to something between 1" to 3". This is to give you an idea of the range we're thinking off. Don't go making a diffuser off of this top-of-my-head data... :D
Cheers,
Sigert
Ps. There was a link somewhere here on the forum to BBC research papers on diffusers. I'll post it as soon as I find it again.
Interesting - thanks! anyone else wanna chime in? :)About bookshelf diffusers and diffusers in general: Without going into the math of it, the frequency range in which a diffuser shows effect depends on mainly 2 factors: 1) maximum depth of the construction 2) number of variations in depth These two factors make that a good, broadband diffuser will take up much room, as it has to be a deep construction with as many variations as possible. This makes at least one reason diffusers are not first choice within small space acoustic treatments. There are better space/effective measures that can be taken. The bookshelf diffuser is quite an appealing idea, and it does provide improvement to some extent. it's good in terms of variation in depth, thus being good at diffusing the frequencies effected by it. It's not very deep though, so the frequency range it will affect is rather small. For all I know though, it 'll only be worth the trouble/space in rooms of considerable size that were already quite good sounding before the bookshelves were placed. To act as a diffuser, your beams will be: 1) too far apart 2) lacking variation in depth Calculating the correct distance between variations in depth will bring you to something between 1" to 3". This is to give you an idea of the range we're thinking off. Don't go making a diffuser off of this top-of-my-head data... :D Cheers, Sigert Ps. There was a link somewhere here on the forum to BBC research papers on diffusers. I'll post it as soon as I find it again.
What kind of sonics are you referring to? All that we have at present is the intention to build a flat roof w/ 2X12 joist/rafters with insulation in-between. Are your plans to build the walls the same way? Framing with insulation in-between studs? Floors...same way? http://en.wikipedia.org/wiki/Golden_ratio http://en.wikipedia.org/wiki/Golden_rectangle A better place to start would be a base number, then that number X 1.6 and that same number X 2.6 It would only be "better" in the sense that some effort were put into this desire to have the best available outcome from your many, many long hours of work and expense. For example. If you go through the effort of framing and then add double 5/8 rock to the walls, you defeat the walls by constructing this ceiling/roof that is now the known weakest link and brings everything around it, down to it's level, so to speak. Good Luck,1) i'm keen to absorb some sound - but only for the purposes of the sonics inside the room. I am not concerned with trying to keep sound from leaving the room 2) the joists being across the main sound direction should provide some diffusion. That is the plan.
Unconventional as it may sound, I do believe sound isolation was not an issue in this particular case. If I'm not mistaken, the original question includes only room acoustics. In the light of this starting position, having as much sound leave the room as possible is a good thing. It won't give you happy neighbours, but it will probably ease up the acoustic concerns.
NO - the question was limited to room acoustics within the confines of 2 x 12" ceiling joists..... on a 16" center.... for simplicity... and it is the only problem that I have right now. Sound isolation is well taken care of. 8)Unconventional as it may sound, I do believe sound isolation was not an issue in this particular case. If I'm not mistaken, the original question includes only room acoustics. In the light of this starting position, having as much sound leave the room as possible is a good thing. It won't give you happy neighbours, but it will probably ease up the acoustic concerns.
What about if we use 6 mil poly for a plastic layer below the joists (or maybe Tyvek ?) - with the assembly completely sealed at the perimeter and at all laps - to contain the loose fiberglass insulation.
Then a layer of pegboard nailed up in big sheets
Then completely covered in 2" echo eliminator acoustical cotton material.
http://www.echoeliminator.com/
How does that sound?
Hiya,
I'm not familiar with these materials, so I really couldn't say. But it does sound to me like covering up the fibers with plastic would do the trick. Although being reflective, plastic won't create problems acoustically (given that it's thin enough). So the cotton covering could most probably be left out of the construction.
Cheers,
Sigert
books as random diffusers - random in efficiency to be sure. random in dispersion? possibly. its random chance... as far as open insulation on the floor joists - it is very likely a fire hazard and not to code (open or expose insulation rarely is), so in the event of a fire or other insurance related event, you'll probably lose any renumeration or policy benefits. if you want to go with the route of using the joists as absorbers, add a layer of flame retardant treated cloth over flame retardant rated insulation bats. depending on the room height, paper may help keep some life in the room, as well as plastic sheeting under the cloth. in a low ceiling, just use the cloth. the joists will add some reflection back but it will be highly absorptive.anyone else wanna chime in?
the echoeliminator is to provide broadband absorption from 500 hz up.... http://www.echoeliminator.com/Hiya, I'm not familiar with these materials, so I really couldn't say. But it does sound to me like covering up the fibers with plastic would do the trick. Although being reflective, plastic won't create problems acoustically (given that it's thin enough). So the cotton covering could most probably be left out of the construction. Cheers, Sigert
DO NOT use the pegboard as you will be creating a form of hemholz resonator of unknown frequency response.
What you want to do seems rather simple to me:
Roofing
Joists
fiberglass in between joists
-I would add.....
2" Rockwool 3-5 pcf
fabric covered frames to finish it.
I would cover the whole ceiling in fabric covered frames like Paul Woodclock's place and many others. That stops the fibers from falling and allows a more finished appearance. I would put in the R30 stuff and then put in 2" of the denser Rockwool as the bottom layer, then fabric frames to cover. Really good for acoustics even down into the bass.
Don't consider the beams as a diffusing device as they will be more of a diffraction grating due to the regular spacing, not good.... Filling the fiberglass/rockwool combo all the way to the edge of the joists should eliminate this issue.
Oh yea, since you are building from the ground up, use an optimal ratio. No reason why not at this point. It'll help the bass response in the room.
Good luck,
ashley
Thanks for the good info Ashley my thoughts are: 1) building 500 square feet of fabric in frames will be WAY expensive for both materials and labor. 2) how would the fabric hold all the weight of the insulation up? or - how is all the insulation actually held up? 3) I'll have track lighting right there... the city planners and fire dept might not like that... (you said) - DO NOT use the pegboard as you will be creating a form of hemholz resonator of unknown frequency response. I know what a helmholtz resonator is... can you elaborate on your concerns? thanks! :)DO NOT use the pegboard as you will be creating a form of hemholz resonator of unknown frequency response. What you want to do seems rather simple to me: Roofing Joists fiberglass in between joists -I would add..... 2" Rockwool 3-5 pcf fabric covered frames to finish it. I would cover the whole ceiling in fabric covered frames like Paul Woodclock's place and many others. That stops the fibers from falling and allows a more finished appearance. I would put in the R30 stuff and then put in 2" of the denser Rockwool as the bottom layer, then fabric frames to cover. Really good for acoustics even down into the bass. Don't consider the beams as a diffusing device as they will be more of a diffraction grating due to the regular spacing, not good.... Filling the fiberglass/rockwool combo all the way to the edge of the joists should eliminate this issue. Oh yea, since you are building from the ground up, use an optimal ratio. No reason why not at this point. It'll help the bass response in the room. Good luck, ashley
You should hold up the insulation with something like chicken wire or other metal stays. Some simple wood blocking might do the trick as well.
You could just stretch fabric across all the joists and staple it in to each joist to make the covering more affordable. Put some little trim strips over the staples to cover it up.
Mount the track lights on the joists or create some blocking inbetween that will support the lights. You need to have fire-retardent (sp?) fabric up there anyhow for safety.
The pegboard is a perforated board that creates a resonant chamber behind it. Calculating the hemholtz resonance of that system is difficult. It's just like slat resonators but with little holes instead of slots. Same principle.
I just re-did the acoustics in the mastering studio by removing an old pegboard false wall and replacing it with simple rockwool and fabric frames and the sound was so much improved. The pegboard sucked a huge amount of lower-mids/upper bass out of the room to the point where I really couldn't do my best work in there. Pegboard= BAD unless you calculate the result and actually need that result in the first place.
-ashley
pegboard has a high percentage of perforations which cause it to be a mid-high absorber - so as bassman points out, it can be difficult to predict unless you work out the percentage of perforations on the material you have and calculate based on that. most times, if you're building a perforation based panel, you would drill in the holes as needed, with a given depth etc to ensure it works on the targeted frequency range.
insulation can be help up with insulation mesh (plastic or wire), metal wire (stays/clips), metal or plastic pins/hooks, or zig zap some line across the studs or joists.
thanks for all the good info everybody!!!
:D
Btw, I found that thread I mentioned earlier. The one in which possible health risks of fibreglass are discussed.
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1742
cool - thanks! 8)Btw, I found that thread I mentioned earlier. The one in which possible health risks of fibreglass are discussed. http://www.johnlsayers.com/phpBB2/viewtopic.php?t=1742
check out the ceiling in this studio
http://johnlsayers.com/Studio/Mainpage/MP-Funky_1.htm
the black plastic was then covered in cloth.