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Wrapping MLV around bolt for noise isolation?
Old 3 weeks ago
  #1
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Wrapping MLV around bolt for noise isolation?

I am making a soundproof chamber and in order to isolate the frames (walls contain so the room can be removed), I was considering using MLV around the bolt and between the washer. So, I will cut out small MLV pieces for the ends (like washers, slightly bigger than the washers), and cut MLV pieces to wrap each bolt with.

The goal is total isolation of the bolt from the wood that it is holding together.

Here is my design:

https://i.imgur.com/hwvDMvr.png

Here's an actual product sold for this very purpose, and there are others, called bolt sleeves:
https://www.farwestcorrosion.com/iso...rs-by-gpt.html
Also, acoustic washers, although they don't do much without the sleeve:
https://www.farrat.com/anti-vibratio...tic-washers#15

What I'm doing is basically that, just with MLV as the isolating later.

I ran into a couple challenges.

1. I realized that wrapping the bolt with 1/8" (1lb) MLV will increase the diameter by 1/4". I figured, I could calculate for the hole size, and add the MLV, and add a small space to make it easy to insert. I thought 1/32" around the hole? Is this enough?

2. The extra 1/8" width of the MLV will cause the shaft+MLV to be the same size as the head (and nut). I will be using a washer, but with the washer, it's only 1/8" larger in diameter than the hole. I could use a bigger washer which will add 1/8 inch, but with 1/8" washer bigger than the hole, while the head is the same size as the hole, will that work?

3. Will this design allow both sound isolation as well as structural integrity holding together 4' x 4' 2x4 frames?

Also I'm wondering if this will be worth the hassle, over simply bolting it together. (Bolting it together is so that the room will be removable, as the house I am living now is rented. By the way the room is on the ground level, and the house is single-story.)

Note that on the exterior there will be double 5/8 drywall with green glue. I'm considering adding insulation as well as double drywall with green glue on the inside, I plan to do one thing at a time until I achieve the desired isolation.

By the way the project for this room within a room is intended for sleeping, to noiseproof against the outside. This room within a room will also have a floor with double MDF with green glue, isolated from the floor.

The main reason for considering dampening the bolts themselves is to prevent vibration/noise transmission across the structure.
Old 3 weeks ago
  #2
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Jason Foi's Avatar
 

Can you provide drawings of your wall design so i can be clear on what your goal is, please? This shouldn't be necessary for a room within a room. Also, provide details of what frequencies you are isolating, their levels, and sources.
Old 3 weeks ago
  #3
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I don't know the exact frequencies but I believe it's lower frequencies. I'm not sure how to measure it, but it isn't something I can actually hear, because it merely wakes me up during the night, and I want to sleep without earplugs, and even with earplugs I still get woken up.

It's a wall, ceiling, and floor. It is two frames made of 2x4s bolted together for each wall, ceiling, and floor. Then walls bolted to each other, and to the floor and ceiling.

I've already built the frames. Waiting on the green glue to arrive before picking up the drywall.
I also already have the bolts, washers, and nuts.

It will certainly be easier to do this project without isolating the bolts, because although that is ideal, it would be a lot more work.

Here is a picture of the frames dimensions that are now built, including the door which I just completed.

https://i.imgur.com/aeRmYBY.png

Note that besides the frame sides, there are 24" spaced studs on the 4' frames and 18" spaced studs on the 3' frames (in the middle). That's what the tan lines are. While the frames are 2x4, the studs are 2x3s to achieve better isolation.
Old 3 weeks ago
  #4
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Jason Foi's Avatar
 

Quote:
Originally Posted by QuietSleepNow View Post
I don't know the exact frequencies but I believe it's lower frequencies. I'm not sure how to measure it, but it isn't something I can actually hear, because it merely wakes me up during the night, and I want to sleep without earplugs, and even with earplugs I still get woken up.

It's a wall, ceiling, and floor. It is two frames made of 2x4s bolted together for each wall, ceiling, and floor. Then walls bolted to each other, and to the floor and ceiling.

I've already built the frames. Waiting on the green glue to arrive before picking up the drywall.
I also already have the bolts, washers, and nuts.

It will certainly be easier to do this project without isolating the bolts, because although that is ideal, it would be a lot more work.

Here is a picture of the frames dimensions that are now built, including the door which I just completed.

https://i.imgur.com/aeRmYBY.png

Note that besides the frame sides, there are 24" spaced studs on the 4' frames and 18" spaced studs on the 3' frames (in the middle). That's what the tan lines are. While the frames are 2x4, the studs are 2x3s to achieve better isolation.
When we are building for isolation the best practice is a 2 leaf fully decoupled MSM system. To do this we need the outer layer/framing and the inner layer/framing to never come into contact with eachother.

It sounds like are you are building a free standing structure inside your existing room. If so, there is no need to try and decouple bolts on their respective frames. You would only want to break mechanical connections if you were attempting to secure the outer leaf to the inner leaf (or vise versa), which should be avoided at all cost.

I dont know your buildings current construction, but you seem to be potentially creating a 3 or 4 leaf system, which is bad. If you are on slab on grade, decoupling the floor is not necessary in most cases.

Please provide more details of current construction and drawings of leaf locations, and spacing.

Your current drawings lack many details.

Also, for isolation to work we require airtight cavities. This is bad for people. You must have a ventillation system in your design at minimum.
Old 3 weeks ago
  #5
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The room is not on slab. It is on wood and carpet with a crawl space. Floor isolation absolutely needs to happen, as vibrations are being felt through the floor.

I am not building a 3 or 4 leaf system. Consider this as a separate structure. The outer room which is exposed to the outdoors on the other side of the wall is not part of this structure. It will not create the 3-leaf as I am not building 2 walls with drywall in between. There will be quite an air gap of 1 foot to 10 feet between the size of the room and the size of this inner room. It is a very large room. Also above there will be about 12 feet+ between the ceiling of the inner room and the roof of the room, the ceiling is nearly 20 feet high.

I already mentioned it is 2x4s. This means the gap between the outside and the inside is 3.5" since that is the depth of a 2x4.

I didn't mention that I do have a good ventilation system designed already. Good tip, but I did consider ventilation.
Old 3 weeks ago
  #6
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Kyle P. Gushue's Avatar
A leaf is can be a mass sheet. So your outer walls can only have sheathing on outer side, your new inner walls, on the interior. With a 10-12ft gap the triple leaf effect is basically not an issue. 1 ft can be an issue. The distance is between the two mass layers not the frames, so a typical double 2x6 wall has about a foot between the mass layers.

Your floor will require very careful planning. You will have to most likely incorporate a massive floating floor of some type. This is not a diy part of the project.
Old 3 weeks ago
  #7
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Quote:
Originally Posted by Kyle P. Gushue View Post
...(mindless rambling)...
Yes it is a DIY part of the project. The whole thing is DIY.

I already ordered rubber feet (forget the name, it's for noiseproofing, I need 20 for my size room) for this purpose and there will be two sheets of 3/4 MDF layered with green glue in between. This will be a totally isolated floating floor. Not very much "careful planning" needed, besides the careful planning already planned.
Old 3 weeks ago
  #8
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Kyle P. Gushue's Avatar
Quote:
Originally Posted by QuietSleepNow View Post
Yes it is a DIY part of the project. The whole thing is DIY.

I already ordered rubber feet (forget the name, it's for noiseproofing, I need 20 for my size room) for this purpose and there will be two sheets of 3/4 MDF layered with green glue in between. This will be a totally isolated floating floor. Not very much "careful planning" needed, besides the careful planning already planned.
Im not sure what you expect to isolate with that, but that's generally not going to work. Your effectively building a big drum head and wasting money.

You need mass, significantly more than 2 sheets of mdf. You need the floor to have a resonant frequency of preferably lower than 10hz. GG doesn't aid this goal. Think concrete slab here...

Have you looked at the test data for the assembly you so carefully planned? This is doubtful.
Old 2 weeks ago
  #9
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Quote:
Originally Posted by Kyle P. Gushue View Post
...(rambling about nonsense)...

I'm sure at this point that you have no idea what you're talking about. I will ignore future posts from you.

Open to hearing real advice from people who actually know something, looking forward to replies.
Old 2 weeks ago
  #10
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Kyle P. Gushue's Avatar
Quote:
Originally Posted by QuietSleepNow View Post
I'm sure at this point that you have no idea what you're talking about. I will ignore future posts from you.

Open to hearing real advice from people who actually know something, looking forward to replies.
Ok buddy have fun. The title of this thread is "wrapping bolts with mdf". That shows your not qualified to judge my level of knowledge. "2 layers of mdf creating a totally isolated floor" further reinforces your level of misinformation.

Have fun. Remember after your project turns out to be a waste, that you heard it here first.
Old 2 weeks ago
  #11
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Kyle P. Gushue's Avatar
You misquoted me.
Old 2 weeks ago
  #12
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Jason Foi's Avatar
 

Quote:
Originally Posted by QuietSleepNow View Post
I'm sure at this point that you have no idea what you're talking about. I will ignore future posts from you.

Open to hearing real advice from people who actually know something, looking forward to replies.
His concerns are legitimate
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