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A compromise for independent basement room???
Old 20th May 2020
  #1
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A compromise for independent basement room???

I'm building a room in the basement of a house that I'll soon be moving into. The house has a large unfinished open area where I'm doing a 16'x24' room currently planned to have no linkage to the existing framing of the house. The goal is to dramatically reduce footfall noise AND minimize transfer to the living area above. Originally I'd planned on framed walls outset slightly from the block basement walls on 2 adjacent sides of the room. So, a key working principal is that by having this room touching the existing structure only where the framing sets on the massy basement floor, I take advantage of the mass of the floor to minimize transfer to the structure. Now, I think of the block walls that I'm building parallel to as also being "massy" similar to the concrete floor. So, a compromise I'm considering is to not outset framed walls along the block wall, but instead to hang my new room's nested ceiling joists on the sill plate at the top of that block wall, knotching the ends of the ceiling joists to drop them to create the offset for my ceiling from the bottom of the floor joists above. The opposite wall would be an independently framed wall supporting the joists. My thinking is, yes I realize I'd be linking to the existing structure along this 24' perimeter wall, but it will be to the sill plate that is tightly linked to the massive block wall along that one wall (albeit also to the house's framing as well via the sill plate). Life is full of compromises. I wonder since my goal is reduction, not an unreasonable expectation of a "soundproof" room, if this compromise might be worth considering? This compromise could save me from building framed walls parallel to the basement's block walls on 2 sides of the room. I appreciate all the knowledgeable input from the clearly experienced contributors to this forum.

Thanks,
BW
Old 20th May 2020
  #2
edit: sorry I misread.

I thought you were BUILDING block walls in your basement.

Yeah don’t use the same block walls to support the joists that are supporting the current floor joists.

My recommendation would be to thoroughly evaluate how much isolation you need.

I screwed 2 and caulked 2 layers of drywall to the subfloor then stuffed them with R30 and hung resilient channel, OSB, Green Glue and drywall.

I have more than enough isolation for most stuff and I haven’t even sealed the doors and windows.

For super loud stuff I just wait till no one is home.

If I could do it again... I think I would rather have the ceiling height for absorbers as opposed to the isolation I gained...considering all the time and money it cost.

Last edited by Grovestand; 20th May 2020 at 07:45 PM..
Old 20th May 2020
  #3
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Kyle P. Gushue's Avatar
Quote:
Originally Posted by Burstwurst View Post
I'm building a room in the basement of a house that I'll soon be moving into. The house has a large unfinished open area where I'm doing a 16'x24' room currently planned to have no linkage to the existing framing of the house. The goal is to dramatically reduce footfall noise AND minimize transfer to the living area above. Originally I'd planned on framed walls outset slightly from the block basement walls on 2 adjacent sides of the room. So, a key working principal is that by having this room touching the existing structure only where the framing sets on the massy basement floor, I take advantage of the mass of the floor to minimize transfer to the structure. Now, I think of the block walls that I'm building parallel to as also being "massy" similar to the concrete floor. So, a compromise I'm considering is to not outset framed walls along the block wall, but instead to hang my new room's nested ceiling joists on the sill plate at the top of that block wall, knotching the ends of the ceiling joists to drop them to create the offset for my ceiling from the bottom of the floor joists above. The opposite wall would be an independently framed wall supporting the joists. My thinking is, yes I realize I'd be linking to the existing structure along this 24' perimeter wall, but it will be to the sill plate that is tightly linked to the massive block wall along that one wall (albeit also to the house's framing as well via the sill plate). Life is full of compromises. I wonder since my goal is reduction, not an unreasonable expectation of a "soundproof" room, if this compromise might be worth considering? This compromise could save me from building framed walls parallel to the basement's block walls on 2 sides of the room. I appreciate all the knowledgeable input from the clearly experienced contributors to this forum.

Thanks,
BW
I've not seen any test data on an assembly like this. It really depends on how much isolation you need. Id be concerned with how close the houses joists and ledger board for new joists are, considering they are right at the top of the wall.

Then you are dealing with a non symetrical set of walls from a frequency response perspective. One wall is going to have a different FR than the other.


To me it seems like an excessive chance without any data to back it up. I've never seen any respected acousticians calling for this type of design, which leads me to believe its not effective.

To couple the ceiling, and omit a wall worth 20db or more just doesn't justify any sort of savings financially to my mind.
Old 20th May 2020
  #4
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I'm talking about my studio room's ceiling joist's resting on the same 2"x6" plate that tops concrete block basement wall and supports flooring and the structure above (my new ceiling joists being placed mid-way between the existing floor joists above, along only the 24' long west wall which is one of the basement block walls). In my mind I try to (loosely) equate this interface between ceiling and structure to what is gained by doing a staggered stud wall on a 6" plate.

Both thoughtful replies included something like "depends on how much isolation you want?". That's key here, I want a substantial improvement over doing nothing or doing standard construction as though it were a bedroom, or doing a shoddy job of building a poorly planned studio room in my new house.

I just spoke with my new neighbor most affected, who's sister is one of the gals in the 3-girl "choir" in my band, explained what I was doing, and he said he wouldn't be bothered a bit by the kind of music I play and produce. A helpful situation!

Oh, and there's another thing,,,,,,, In this basement, along this subject wall, there had been a minor, but, meaningful water seepage through the wall/floor interface. Recent dirt work I've done outside withstood a freakish 3 inch rain over a 30 minute period just after my dirt work, with no leakage. But, with this water history, and considering the loss of floor space as a result of insetting separate framed walls inside the existing block wall(s), I'm really tempted to take a chance on this uncharted (hybrid ceiling support concept) territory. If I can still get decent transmission reduction to the upstairs of the house AND leave the area where there is a water leakage concern open for observation I could avoid the anxiety of fearing that my dirt work solution could fail and wreak havoc. It's easier because this is in my home / my studio, with only my family to be concerned with. My gamble won't be affecting a customer client.

Regarding my ceiling joist support scheme, my mind tries to simplify things..... trying to rationalize that the ceiling supported by the block wall only along that one wall (perhaps with some sort of "suspension") could still be a meaningful improvement over other more costly and space consuming alternatives. When considering the transmission, I keep visualizing what I hear when I put my ear right next to the 12th fret of a guitar and what I hear when I place my ear at the nut (or bridge), both a dramatic reduction in amplitude. A little out there, but, maybe you follow me here. My transmission through the new ceiling joists on this will only be through "at the nut", so to speak. Hope you're following my figurative language.

Tolerant neighbor, loose requirements, really tempted to re-claim the floor space with this approach.

Thanks, both of you for the thoughtful replies. Getting close to "Hammmer time", gotta finish up full kitchen and family room renovations first (3-4 weeks from completion on that), then into the studio build.

BW
Old 20th May 2020
  #5
Quote:
Originally Posted by Burstwurst View Post
I'm talking about my studio room's ceiling joist's resting on the same 2"x6" plate that tops concrete block basement wall and supports flooring and the structure above (my new ceiling joists being placed mid-way between the existing floor joists above, along only the 24' long west wall which is one of the basement block walls). In my mind I try to (loosely) equate this interface between ceiling and structure to what is gained by doing a staggered stud wall on a 6" plate.

Both thoughtful replies included something like "depends on how much isolation you want?". That's key here, I want a substantial improvement over doing nothing or doing standard construction as though it were a bedroom, or doing a shoddy job of building a poorly planned studio room in my new house.

I just spoke with my new neighbor most affected, who's sister is one of the gals in the 3-girl "choir" in my band, explained what I was doing, and he said he wouldn't be bothered a bit by the kind of music I play and produce. A helpful situation!

Oh, and there's another thing,,,,,,, In this basement, along this subject wall, there had been a minor, but, meaningful water seepage through the wall/floor interface. Recent dirt work I've done outside withstood a freakish 3 inch rain over a 30 minute period just after my dirt work, with no leakage. But, with this water history, and considering the loss of floor space as a result of insetting separate framed walls inside the existing block wall(s), I'm really tempted to take a chance on this uncharted (hybrid ceiling support concept) territory. If I can still get decent transmission reduction to the upstairs of the house AND leave the area where there is a water leakage concern open for observation I could avoid the anxiety of fearing that my dirt work solution could fail and wreak havoc. It's easier because this is in my home / my studio, with only my family to be concerned with. My gamble won't be affecting a customer client.

Regarding my ceiling joist support scheme, my mind tries to simplify things..... trying to rationalize that the ceiling supported by the block wall only along that one wall (perhaps with some sort of "suspension") could still be a meaningful improvement over other more costly and space consuming alternatives. When considering the transmission, I keep visualizing what I hear when I put my ear right next to the 12th fret of a guitar and what I hear when I place my ear at the nut (or bridge), both a dramatic reduction in amplitude. A little out there, but, maybe you follow me here. My transmission through the new ceiling joists on this will only be through "at the nut", so to speak. Hope you're following my figurative language.

Tolerant neighbor, loose requirements, really tempted to re-claim the floor space with this approach.

Thanks, both of you for the thoughtful replies. Getting close to "Hammmer time", gotta finish up full kitchen and family room renovations first (3-4 weeks from completion on that), then into the studio build.

BW
If I had to do it again, I would either build my room inside out ALA John sayers then put the new ceiling joists on the new timber walls or use metal studs for the walls and hat channel and clips for the ceiling.

Or If I was less concerned with isolation (which I am now) I would just attach layers of drywall and caulk to the subfloor put in a drop ceiling with NRC 0.95 tiles and fill the whole thing with R30 to make a huge ceiling cloud.

The block wall is massive, but the distance between your joists and the floor joists will be tiny.

Using fuzzy math and eyeballing it I can confidently say with no credentials that Low frequency energy will definitely travel to them. Then you will rip out your ceiling and add hat channel and clips double drywall with green glue and be happy. $1000s of dollars and hundreds of hours later.
Old 20th May 2020
  #6
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I say fix the water leakage, if it needs it.

By resting the studio joists on the same footer as the floor above, your defeating the purpose of an independent ceiling. Wood transmits sound very well, your guitar is made of wood for a reason. Your creating a direct path for vibration to travel.

Your really only saving 6-8" of floor space, but sacrificing a huge chunk of isolation.

It's really going to turn the expense of the other walls and ceiling into significant waste.

Neighbors can move and relationships can sour.

You could look into kinetics ICW spring clips (or similar) and perhaps attach the new joists to those so there is decoupling between the new and old joists, without need for an additional wall.

Its your place, but all i can say is if resting new joists on the sill plate worked, we would know by now.

Best of luck, hopefully your proper planning and design won't require any luck.
Old 15th June 2020
  #7
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The compromises just keep on coming. Because of the uncertainty of the leakage issue, I'm going to have to leave the 2 block walls exposed. So, I've decided to hang double drywall from resilient channel for my ceiling. My ceiling drywall will interface with the block walls. I plan on sealing the interface using backer rod and green glue.

- Is there some other product that would create a better seal at the ceiling/block wall interface?
- I'll be stuffing the space between the floor joists with insulation. Should that insulation be paper-side down? What type of insulation is most appropriate?
Old 15th June 2020
  #8
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You cited impact noise as a concern, the resillient channel won't do much for that, the channel also reduces low frequency isolation, and trades it for mid/high isolation. Not great for music, better geared for bedrooms or regular living rooms for tv or conversations.

These will work better for footfall
https://kineticsnoise.com/arch/icw.html

At minimum i would consider whisper clips or risc1 clips instead of resillient channel.

For perimeter ceiling do not use green glue, that's not what its for. Use the backer rod and 100% silicone, or butyl caulking. Standard non hardening caulking.

As far as insulation just use the standard fluffy R-value insulation, sized for the size of the joists. Nothing special here. I would go with paper side down, unless code specifies otherwise.

I would also very seriously consider adding drywall layers, in between the bays, before covering up the ceiling. Otherwise if you need more isolation in the future you would have to rip out and re use the DW you attached to the decoupling clips.

Its still critical to locate the leak. You wouldn't want any water getting in between your new ceiling and the floor above. If the leak is up thru the floor then a sump pump or french drain may be needed. A sump pump isn't a big deal. After flooding for a decade with inches of water a couple times a year, the house im in got a sump pump, it still got a little water so we made the hole deeper and the basement no longer gets water.

You may need a dehumidifier as well to prevent mold. You can drain the dehumidifier into the sump pump for a set and forget moisture control system.
Old 15th June 2020
  #9
You cannot hang drywall next to your exterior block wall.

That is guaranteed to lead to mold. It also will not provide any isolation, since you will have a 2 leaf ceiling and a 1 leaf Wall.

Also, don’t put paper faced insulation in the cavity between your basement and the room above. There’s no need for a vapor barrier.
Old 17th June 2020
  #10
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Quote:
Originally Posted by Grovestand View Post
You cannot hang drywall next to your exterior block wall.

That is guaranteed to lead to mold. It also will not provide any isolation, since you will have a 2 leaf ceiling and a 1 leaf Wall.

Also, don’t put paper faced insulation in the cavity between your basement and the room above. There’s no need for a vapor barrier.
I guess I wasn't clear. The water leakage at the floor/wall interface has forced more sacrifice. I'm now planning to use resilient channel to hang a double drywall ceiling. This ceiling will abut (perpendicularly) against the 2 vertical block walls (forming one corner of a large basement). At that joint (drywall ceiling/bloc wall) is where I'm trying to discover (or design?) the best method to establish the best resilient acoustic seal (between the ceiling and the block basement wall). I remember using a black, dense "foamy" adhesive backed strip, building double glass studio windows years ago, used it to mount the glass. Anyway, looking for the best way to seal that off.

Insulation : seems given a flexible budget, additional $ spent on insulation (from above) between my existing floor joists (above). What type/rating insulation should I be looking at?

I'm working now on prepping walls and floor for coatings and leveling.
Old 17th June 2020
  #11
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Quote:
Originally Posted by Burstwurst View Post
I'm now planning to use resilient channel to hang a double drywall ceiling.
From post 8:
Quote:
You cited impact noise as a concern, the resillient channel won't do much for that, the channel also reduces low frequency isolation, and trades it for mid/high isolation. Not great for music, better geared for bedrooms or regular living rooms for tv or conversations.
Kyle was being generous. Resilient channel will make the footfall noise louder.
Old 17th June 2020
  #12
Quote:
Originally Posted by avare View Post
From post 8:
Kyle was being generous. Resilient channel will make the footfall noise louder.
A carpet on the floor upstairs with a thick pad can help with that to some extent.

My point is that there are a lot of reasons that you can’t abut a leaf of your ceiling to the block wall.

Moisture is one reason. If you’re installing a wall in a basement you are supposed to leave a gap between the wall and the floor, the same is true if you are hanging a ceiling next to a block wall.

You could try to cover or fill this gap, but if you only leave half an inch and then put up backer rod and caulk I still think that your drywall will have issues.

If you’re worried about water, maybe you should use Magnesium oxide, metal studs, and foam insulation instead of drywall for the walls of your inner leaf?
Old 18th June 2020
  #13
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Quote:
Originally Posted by avare View Post
From post 8:
Kyle was being generous. Resilient channel will make the footfall noise louder.
Thank you for clarifying.


Quote:
Originally Posted by Grovestand View Post
A carpet on the floor upstairs with a thick pad can help with that to some extent.

My point is that there are a lot of reasons that you can’t abut a leaf of your ceiling to the block wall.

Moisture is one reason. If you’re installing a wall in a basement you are supposed to leave a gap between the wall and the floor, the same is true if you are hanging a ceiling next to a block wall.

You could try to cover or fill this gap, but if you only leave half an inch and then put up backer rod and caulk I still think that your drywall will have issues.

If you’re worried about water, maybe you should use Magnesium oxide, metal studs, and foam insulation instead of drywall for the walls of your inner leaf?
The way to deal with moisture is proper drainage and humidity control. Mold is certainly a serious consideration. It is not a particularly exciting thing but climate control in the basement is critical to the house, its occupants, and the value of the investment. I hope the OP does things in the correct order..

Im not entirely sure that a caulked gap between concrete and DW is an issue, if the basement has properly handled moisture issues. There are well designed pro studios that have bare concrete floors, and drywall walls which is similar to what we are discussing here. These walls have to be sealed in some way, ive never seen any special consideration with regard to sealing in this case.

Metal studs trade LF performance for HF performance which isn't ideal for music. Usually pressure treated wood is required when applying framing directly to concrete, like for footers for example. Foam insulation isn't used for acoustic applications.
Old 18th June 2020
  #14
Quote:
Originally Posted by Kyle P. Gushue View Post
Metal studs trade LF performance for HF performance which isn't ideal for music. Foam insulation isn't used for acoustic applications.
That’s true, but steel, mag ox, and foam don’t grow mold and it would provide better isolation than a 1 leaf wall with no insulation adjacent to a 2 leaf ceiling.

You can add fiberglass insulation to the inside of the mag ox board after it is up.

Of course humidity will have to be addressed if it’s an issue, or you will have mold on the ceiling, bass traps, and anything else you put in the room.

Don’t rush it. Kyle is giving you free advice!
Old 18th June 2020
  #15
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With all the great feedback and suggestions so far, I think I need to better define my project in order to make the most of the knowledge being offered here. This will be my home. My goal is to create a space where I can have casual jams and occasionally record myself and others. Regarding the isolation I'm looking for, I simply want to take measures to improve it. I don't have unreasonable expectations or needs. Just want to do what I can to minimize the rumble in the upstairs living space during a band jam, and minimize footfall noise if possible. The room will be at the opposite end of the house as the master bedroom (which is over a separate crawl space). I have the budget, but because this'll no longer be a working studio, I am staying mindful of diminishing returns.

This room will be in the basement of a mid-50s ranch style home.
- The basement is block wall construction with an I-beam and support posts. The room will be situated between the block walls and the I-beam.
- The water leakage/seepage I'm battling occurs only after very prolonged rain periods and occurs in two isolated places only at the floor/wall interface only. The maximum amount of water after prolonged rain event is no more than a couple ounces. The mold I mentioned was very contained to only the baseboard (of now torn out construction) directly surrounding the 2 leak areas (very minimal, but can't be ignored). I have decided to address the issue by installing a small L-shaped gutter along the floor/wall interface and camouflage it with a cable trough around the perimeter (hiding the gutter while providing access).
- Having made the decision to not cover the block walls and knowing I must build walls opposing both of the block walls, my conundrum is determining the best configuration for the ceiling. So, I had gravitated to using resilient channel thinking it would provide some improvement in isolation (some comments making me question it's validity). I also have another motivation for using resilient channel, it would allow me to avoid interference by a few copper water lines currently routed along the bottom of the floor joists. The offset the channel provides would be enough to clear the water lines.

I've come a long way from my original room within a room design but the water leakage issue has forced my hand, and likely saved me a boat-load of money. Thanks all for the great advice so far!

BW
Old 18th June 2020
  #16
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Your choice in resilient channel works against your desire to mitigate footfall. It also works against the isolation in the low frequencies.

You need to go with one of the clips/channel options or ideally a true room in room.
Old 19th June 2020
  #17
Is your basement Floor Level?

I ask because if it’s perfectly level and you only get water in two places after heavy rains then it probably isn’t the water table rising, its surface Water puddling and then getting in between an unsealed space between the footer and the block wall.

That might be addressed by gutters, irrigation, or grading.

Otherwise, I assume that you don’t have enough room to build the jam space with a large corridor around the outside? If you could do that then you could build a room within a room.

How loud are you playing?

I’m just guessing, but I would bet that 41Hz at 100dB is going to shake the block wall and all the wood that’s sitting on it.
Old 19th June 2020
  #18
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The floor is reasonably level, sloping towards the drain at the opposite corner of the basement. Outside of the house along the wall where the leaks are, I've cleaned gutters, raised my window well tops and added dirt to increase the slope away from the house. Considering larger gutters and diverters. How loud?.... Tweed Deluxe, Portaflex, 147 Leslie loud...... not very loud.

Thanks for putting me onto the RSIC-1 clips. I'm convinced that 2 sheets of drywall with green glue hung from RSIC-1 clips will give me the most bang for the buck. Because I do not have concerns over moisture issues at the top of the block walls, I still hope to interface the ceiling to the block walls with backer rod and caulk.

- Would I see any improvement by using different thicknesses of drywall for the 2 ceiling layers?

- For interfacing the ceiling to the blocks, what caulk would be most appropriate?

The RSIC-1 clips provide the clearance I need for any obstructions (air returns and water lines). So, unless my ceiling plan is still flawed, seems I'd be good to go to begin erecting the ceiling abutting the blocks with backer rod and caulk and stopping just short of the I-beam??? Inviting y'all to save my ass one more time before I start ordering materials. Thanks for all the advice so far!
Old 19th June 2020
  #19
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Quote:
Originally Posted by Burstwurst View Post
- Would I see any improvement by using different thicknesses of drywall for the 2 ceiling layers?
NO!

Quote:
- For interfacing the ceiling to the blocks, what caulk would be most appropriate?
Acoustic caulk. It remains pliant.
Old 19th June 2020
  #20
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I have MANY 2'x4' drop ceiling panels I've removed from the previous construction. Might these panels be repurposed to any positive affect? I saved them thinking I'd cut them at 14 1/2" and tack them to the underside of the sub floor before placing my insulation. Any benefit or detriment in incorporating this material as additional insulation? Regarding the pink insulation, my budget allows for using more or better insulation between the floor joists (and in my 2 framed walls). What are my best choices here?

I'm faced with removing paint (some flaking and some well adhered) from the block concrete walls. Anyone aware of any "magical tool" or process that might make this task easier/quicker?
Old 19th June 2020
  #21
Quote:
Originally Posted by avare View Post
NO!

Acoustic caulk. It remains pliant.
OSI 175 is good, but it is such a pain in the ass to clean up which makes finishing a bit of a nightmare.

Take this with a grain of salt. I am a complete amateur...

If it’s just a little bit of water, personally in my own home, I would drylock the walls, and put up 2” foam insulation.

I’d install dricore for the subfloor of the room.

Build your walls John L sayers style (inside out). For the bottom 2’ of the wall I would use cement board. For the top, you could use drywall on the first layer and ground contact plywood for the second.

Caulk the seams on the wall then paint it with more drylok. Put it up, and leave a gap between the wall and the foam insulation.
Old 19th June 2020
  #22
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Quote:
Originally Posted by Burstwurst View Post
I have MANY 2'x4' drop ceiling panels I've removed from the previous construction. Might these panels be repurposed to any positive affect? I saved them thinking I'd cut them at 14 1/2" and tack them to the underside of the sub floor before placing my insulation. Any benefit or detriment in incorporating this material as additional insulation? Regarding the pink insulation, my budget allows for using more or better insulation between the floor joists (and in my 2 framed walls). What are my best choices here?

I'm faced with removing paint (some flaking and some well adhered) from the block concrete walls. Anyone aware of any "magical tool" or process that might make this task easier/quicker?
Standard fluffy insulation is all you need.

If the subfloor is a wood framed deck, it needs to be filled with sand so it doesn't act like a drum head.

Maybe the ceilinh tiles can be used for some gobos.

Are you adding mass to the existing ceiling above? If so you have to do it before you install the clips and channel.
Old 19th June 2020
  #23
Are the ceiling tiles fiberglass or cellulose/gypsum/crumbly stufff?

If the latter you can probably ditch them.

If they’re yellow fiberglass with a white facing then they’re probably something like OC701. Remove the facing and they should function similarly.

I like 701 because you can put it in front of a bass trap made of pink fluff or safe’n’sound and you don’t have to worry about lumps showing through the fabric.
Old 27th June 2020
  #24
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OK, I've decided that my ceiling (2 - 5/8" drywall, green glue between) will be hung from RSIC-1 clips. It will interface with the very top of the 2 concrete block basement walls with backer rod and acoustic caulk. On the opposing sides of the room (opposite the block walls), the new ceiling stops just short of the I-beam running down the center of the basement (dividing the basement into my music room and workshop) and the other framed wall, separating the studio from another living area. Those 2 framed walls will utilize backer rod and caulk to interface with the ceiling. How should my walls best interface with the basement floor? While I'm still stripping old paint from the block walls and implementing my moisture control system, I'm anxious to learn all about where my plan has shortcomings.

Here's where I wonder if I don't have a real opportunity. The house (ground floor) is now down to the raw flooring. Plank laminate flooring will be soon going in over the entire upstairs. Should I be considering some "barrier" under the new floor?
Old 27th June 2020
  #25
Quote:
Originally Posted by Burstwurst View Post
Should I be considering some "barrier" under the new floor?
If you can isolate the outer leaf (subfloor above) then that would be good, but expensive.

But the weight it could add significant load to your structure and you should get approval from an engineer.

Do you have Rod Gervais’s book?

It answers all your questions in much greater depth than you will find here.

He addresses isolation of floors above studios and interfacing drywall and basement flooring.
Old 25th August 2020
  #26
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Thanks for thoughts and suggestions so far! I've had what I believe is a lucky CL find, having purchased 14 4' x 8' x 2" sheets of Owens Corning theater board "Select Sound Black Acoustic BD" (the black stuff you see on theater walls). Would love to hear your ideas on how to best utilize this material in my new 16' x 21' x 8' room.

Thanks,
BW

Last edited by Burstwurst; 25th August 2020 at 11:28 AM.. Reason: added ceiling height
Old 25th August 2020
  #27
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Quote:
Originally Posted by Burstwurst View Post
Thanks for thoughts and suggestions so far! I've had what I believe is a lucky CL find, having purchased 14 4' x 8' x 2" sheets of Owens Corning theater board "Select Sound Black Acoustic BD" (the black stuff you see on theater walls). Would love to hear your ideas on how to best utilize this material in my new 16' x 21' x 8' room.

Thanks,
BW
Ive never used it. Based on the data sheet it looks like it could be useful on the ceiling to grab mids and highs to preserve ceiling height. It depends if your hanging nice thick clouds for bass trapping.
Old 25th August 2020
  #28
Damn that is a score!

OC703 provides a nice finished front cover for bass traps.

It provides the most acoustical benefit when used in membrane absorbers, at the back of a fluffy trap, or in absorbers that are less than 8” thick (I may be misremembering the oft repeated best material for X thickness rule, but it’s available, Jens posts it all the time).

It’s good at FR points. It’s also nice when you have a few lingering high mid issues that you can’t figure out.

It depends on how much work you want to do. Since they fit your 8’ ceilings I would probably use them floor to ceiling in some areas after you have gotten the bass under control.

Don’t put 2” on every wall, you will end up with a very unpleasant sounding room.

Oh they would make it very easy to build a fluffy wall! You could use wood as vertical supports and use the 2” 703 as horizontal supports. They should be able to support 1-2 layers of R30 with just a few vertical supports.

You could also cut holes the size and height of your speakers and use it to make a soft soffit (though there’s a lot of debate as to whether that’s worth the trouble. Lucky for you it wouldn’t be much trouble at all!
Old 11th September 2020
  #29
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Second layer of drywall (with green glue) going up on the ceiling tomorrow. I've got all this (14, 4'x8' sheets) 2" theatre black insulation and want to be sure I use it to my best advantage. Room is 16' x 21.5' x 8'. I definitely want to hang insulation panels from the ceiling and construct bass traps in all corners. After traps and ceiling are done, the remaining insulation can be placed around on walls. Question is, how much absorption will be too much. I'm blessed to have all this theater black, but also don't want to over-do it either.
Old 11th September 2020
  #30
Cool! Nice to see your build coming along!

There’s no way to know what that stuff will do if you stack it in layers based on the data sheet.

It does say that 2” mounted type A (directly on the wall) has an NRC of .18 at 125Hz. That Means it will absorb 18% of the sound that passes through it.

You should measure your room to find your listening position and try to deal with low frequency issues before moving on to treating the mids and highs.

Lucky for you it fits your wall to ceiling height exactly so testing should be easy.

At a guess, I would say that this stuff would make a nice cover for a deep fluffy trap.

Cover your rear wall with r38.

Cover the R38 with the OC black board. That’s 4 sheets.

Maybe do the same thing for your RFZ, once you’ve decided on speaker placement and listening position.
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