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Discussion Starter · #1 ·
I am finishing up the planning stages of my home theater and had some questions, as some of my plans are drawing the most amazed looks from people.


#1: I plan on using 3/4 MDF on a standard walls built inside the current room. These walls will be completely filled with sand.


#2: The Ceiling will be built to sustain several tons of roof load and will be covered with a thin sheet of plastic and then load up the sand, but only about 1" thick on the ceiling.


#3: The air into the room will be going through a sound baffle and this sound baffle will run through the risers, which will be filled with...SAND.


My floor is an already existing slab of concrete. I still need to calc the load and add it to the existing load and verify the thickness of the concrete to see if it can support the weight, but I am looking at about 20,000# of sand. The room will be 23'x19', for an 84' perimeter. All wiring will be run in condiut attached to the exterior wall studs and then piped in through conduit into the room. All of these will need to be completely sealed to keep the sand in the walls.


Now my questions are:


Is anybody doing this or has anybody thought about this? I know that it will absorb a ton of sound and vibrations. I also know that many people do this with their stages and seating risers, but I have yet to find a person who will do this with their walls.


Am I on crack? If I am on crack, is this a great idea anyway? (The difference between genius and insanity is not much).


I don't know if this would be "up to code" but I feel that sand is fairly fireproof. I don't know where I could find the calculations for how much sound this would absorb, but I would think it would be substantial. I could add acoustiblok between the inner walls and the outer walls for another 26db, but that may be totally unnecessary. Does anybody know what 2 sheets of 3/4" fiberboard and 3 1/2" of sand would block?


Also, what is the best way to soundproof a door? I person at home depot suggested getting a hollow core door and filling it with sand, but I don't know if he was just making fun of me or if it was a good idea.


Mike Poindexter
 

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I'de hate to see what happens when you bust a watter fitting on your next vacation...... MUD.


But seriously... why not use established materals? Sure sand is safe, but I can't imagine the ammount of dust and other problems you could have over the years. There is a reason most people don't bring 10 tons of the stuff into their houses. Why not concrete at that point. You can get nice 4x8 sheets that you can use any way you would like without the hassle of sand.


As for the door. solid steel door with thick acoustic padding on the inside. Make sure the frame is well cauked and baffled too. I'm curious if a hollow door filled with sand would survive the experiment?
 

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For what it's worth, there is no such thing as a soundproof door--you can get close, but it will cost you dearly (I think the IAC STC 71 door is well over $10K). An IAC STC 51 door will run you just under $3K when all is said and done--and it's a real b*tch to install (shipping weight is 500 lbs.). I speak from experience--it's not fun to install, and even installed, it doesn't block everything as well as I expected/wanted.
 

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I'm not sure about sand in the walls...Sand is very compactable. With a vertical rise of 8', thats alot of pressure for sand to compact. You'll start with an 8' wall full of sand, and end up with a 7' wall of sand over time, with a 1' empty hole behind the wall...What will that do to your accoustics?


That's probably an exaggeration of the settling effect, but I don't see much way around it...Even if you somehow compact the sand in the wall prior to sealing, there will always be more settling over time...Especially with low bass bumping against your walls.
 

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Discussion Starter · #5 ·
Well, I will just add more sand when that time comes. I am going to drill a few holes in the top beam to let me fill the wall up. I can always add more at a later date.


The vertical rise is 9.' I wanted to splay the ceiling, but the roof won't allow it and I am not going to try to raise the roof on my home. Yes, there are some lengths I won't go to...


As for a door, I was thinking of building my own, using whatever materials will be best for blocking the sound. I saw a pretty awesome door at the Eleseye hotel in Hamburg that has a really gnarly door. It had two sets of weatherstripping and dual door jambs. I may try to make something similar, with some form of soundproofing in the middle.
 

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You are nuts (but in a good way).


My concern is that you need to remember that solica dust is a carcinogen, and you don't want to be breating it as it seeps into the room form every direction.
 

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Discussion Starter · #8 ·
I will be putting up a continuous sheet of plastic on each side of the 2x4 studs, then the fiberboard. This should keep all the dust inside.


If silica dust is a carcinogen, then I am already screwed. I live on a farm. The entire surrounding area is full of sand. Technically, it is Hesperia Fine Sandy Loam, but I think that if dirt & dust cause cancer, then none of us are safe.


I am surprised I haven't seen Ron and Ted here egging me on. Maybe it hasn't gotten through the grapevine yet that there is another demented soul here who is going where no man (here) has gone before...


So far, all I have gotten is that I am crazy or Mark Brown and I are crazy. Still, that is none for good idea, none for bad idea and 7 with an opinion of sanity. It's amazing how many psychiatrists we have on this board.


This room will be almost 100% airtight, except of course for the HVAC system, so I don't see dust coming into the room as an issue, but thank you for your concern.


Mike
 

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Quote:
Originally posted by Mr.Poindexter
I will be putting up a continuous sheet of plastic on each side of the 2x4 studs, then the fiberboard. This should keep all the dust inside.

What about electrical intrusion into the room...Outlets, Lights, phone jacks, etc....How will you seal them?
 

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Hi Mike,


Have you run this idea past your home owner’s insurance company for their thoughts on this? Should this extra weight cause some sort of catastrophic structure failure, I'm pretty sure that they would disallow any claim you file.
 

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I think it will be very hard to keep the sand in the walls and ceilings. There will be tremendous pressure from the weight of the sand. It will try to leak out around outlets, lights, cracks in the bottom of the wall, etc. With all that pressure, I don't think a thin layer plastic can stop it. In addition, sand is abrasive so if the sound causes the sand layer on the inside of the room to vibrate it may wear through the plastic. In addition, plastic gets brittle and cracks over time.


Sand is heavier than water. Imagine how hard it would be to seal a wall to contain an 8 foot high column of water.


So as sand escapes into the house you will have a dust problem that would aggravate lung problems and allergies, as well as making a mess.


I am guessing the walls would have to built with studs on either side of a central chamber in order to withstand the pressure from the sand. Then you would still need to build in inner wall on the exposed studs. If you put studs inside the sand chamber the studs will transmit sound through the wall thus defeating some of the advantage of having a layer of sand to limit transmission.


I don't know if 2x4s can handle the weight of the ceiling. You would need to get a structural engineer or architect to calculate loads and design a suitable framing design.


Somewhere I saw a guy drying his sand by spreading it out and using a blow dryer. How and where are you going to throughly dry 20,000 pounds of sand?


I think you would be much better off building a multiple layered wall. If you really wanted to use a lot of mass to limit sound escaping the room, you could build concrete walls and ceiling on the ouside, and use the normal multilayered wall suggested by this forum on the inside.


Or another alternative is to build a underground room for the home theater. The HT room could be connected to the main house by a long tunnel. The sheer mass of the earth between the house and the underground HT room would block the transmission of sound. Then use a seperate heating and cooling system for the underground HT room. Put a well sealed door at either end of the tunnel to the HT theater room. If those two doors and the length of the tunnel don't block enough sound, add more doors.
 

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Discussion Starter · #12 ·
Quote:
Originally posted by settopguy
Or another alternative is to build a underground room for the home theater. The HT room could be connected to the main house by a long tunnel. The sheer mass of the earth between the house and the underground HT room would block the transmission of sound. Then use a seperate heating and cooling system for the underground HT room. Put a well sealed door at either end of the tunnel to the HT theater room. If those two doors and the length of the tunnel don't block enough sound, add more doors.
One of the great things about this system is it would have been cheaper than using accoustic tiles, more effective at absorbing sound transmissions, etc. Now I have suggestions on building a new underground home theater. Although this would be very nice to do and I could choose all three of my dimensions (finally - a 14 ft. ceiling!) I think that would surpass my entire budget by a long shot and then some.


Keeping sand in place and water are two different things. Sand wouldn't wear through a sheet of plastic if it is thick enough and the plastic can be sealed. I can keep the sand inside the walls, but that isn't the main objection from a lot of people here. That means that either I am seeing something visionary that nobody else can see, or I am way off base here. I will hedge my bet on the latter, although I would love to see another loony take up the charge. Even if the sound room would have been better, the sheetrock method is tried and true. Time to stop being an early adopter and put the sandbox plans on the shelf between the DAT, DCC deck, Minidisc player and Iridium Sat phone. At least I have HDTV and as long as there is content to watch, either from providers or things I recorded on the hard drive, I will never give it up.


Maybe I can go back to looking at those plans on the full wall screen...


Mike
 
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