# sound proofing utility room



## BlueBSH (Oct 29, 2009)

I have a room where the furnance and water heater are at (both are gas powered) the room is in a finished basement, but the utlity room is unfinished so the studs are showing in this room for the other rooms walls... now the furance and water heater are loud! (the water heater especially since it has a powered vent fan on it)... is there anyway I can keep this sound out of the rest of the basement? you can hear it in the entire basement and part of the house above it clearly when its running and its annoying... can I stuff insulation in the wall to block some of the noise? or is there a special way to do this? I'd really like to quiet it down and damper the noise some... thanks!


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## pyper (Jul 1, 2009)

I've done a lot of reading on sound isolation (being a bagpipe player).

Most of what you'll read about sound mitigation is based on not knowing the frequencies of the sounds you want to block. There are different strategies you can use for different frequencies. Do you have a high pitched sound, a low pitched sound, or both. I'm guessing it's probably both. You can find out easily if you can make a recording and open it up in Audacity -- open source audio editing software and look at the frequency analysis window.

Somewhere on the internet you can find really cool graphs that show how much of each frequency is absorbed by all sorts of different methods.

Anyway, high frequency sound can be stopped with mass. If you put up more sheetrock, less noise will go through. It's pretty much linear -- if you hang a layer of sheetrock on the room side of the studs it will stop a lot of high frequency noise. Putting batts of insulation will help some, but not a lot. Putting acoustic ceiling tiles (the 2x4 suspended ceiling kind) will help a lot. So will 30# felt.

I'm guessing the room doesn't have a door. If you can put one up, and if it's a tight fitting solid door, then it will stop a lot of noise. But you have a conflict here, because your furnace needs make-up air. I can't help with that You can probably make some kind of baffled tunnel for the air to flow through. The baffles will work to muffle the sound while allowing the air to flow through.

It could be that a lot of the sound you hear in the basement is high frequency noise. If that's the case, then putting carpet (or an actual acoustic treatment) on the walls of the utility room will prevent the high freqency noise from bouncing around so much.

You mention sound going from the downstairs to the upstairs. If it's low frequency sound (the rumble of the motor) then you can put drywall on the ceiling and use special sound-isolation clips. You attach these metal clips to the studs, and then hang the drywall from the clips. That will help to stop the vibrations from going straight through the drywall, into the studs and the then radiating out from the floor. Put some insulation there too.

Unfortunately, sound travels through air, and your furnace moves air. One of the biggest issues in really isolating a room is that sound will move through the ducts and get from one room to another that way. Not much you can do about that.

A lot of the literature you read is also about trying to totally stop the sound. What I ended up doing with my practice room was to design it to greatly reduce the sound in the higher frequencies. You can try a similar approach -- figure out exactly what sounds are most irritating and try to reduce them.

Graphic Standards for architects (in your local library reference section) will show you how much sound can be absorbed with various wall and ceiling strategies.


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## Bob Mariani (Dec 1, 2008)

using insulation will help. But overlaying the drywall with QuietRock is by far the best sound deadening method to use.


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## BlueBSH (Oct 29, 2009)

Bob Mariani said:


> using insulation will help. But overlaying the drywall with QuietRock is by far the best sound deadening method to use.


Looks like that might be a good suggestion, I'll look into it


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## 06bluez (Nov 3, 2009)

what I did that was cheaper than quietrock or greenglue/multiple layers of drywall was to use fiberglass insulation between studs, then cover the walls with pegboard. The holes let sound in and it is deadened by the insulation. It is a very effective sound dampener.


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## BlueBSH (Oct 29, 2009)

06bluez said:


> what I did that was cheaper than quietrock or greenglue/multiple layers of drywall was to use fiberglass insulation between studs, then cover the walls with pegboard. The holes let sound in and it is deadened by the insulation. It is a very effective sound dampener.


Would that be safe to do when your water heater / furance is 12" or less from the wall though? I think I have 12" clearance right now, I'll have to check again.. but its about a foot from the rear of them to the bare studs now... I might want something that is a higher fire rating I'd think?


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## gregzoll (Dec 25, 2006)

Rockwool on the ceiling and walls.


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## pyper (Jul 1, 2009)

06bluez said:


> what I did that was cheaper than quietrock or greenglue/multiple layers of drywall was to use fiberglass insulation between studs, then cover the walls with pegboard. The holes let sound in and it is deadened by the insulation. It is a very effective sound dampener.



What you describe is perhaps an effective way to control reflected sound within the room (as would be useful for a practice room or a recording studio), but it won't really stop much sound.

Do this test: Turn up your stereo really loud. Now put a piece of fiberglass and pegboard on top. Doesn't stop much sound. Maybe 3db, but not the 30 or more that we're probably looking for.


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## Bob Mariani (Dec 1, 2008)

06bluez said:


> what I did that was cheaper than quietrock or greenglue/multiple layers of drywall was to use fiberglass insulation between studs, then cover the walls with pegboard. The holes let sound in and it is deadened by the insulation. It is a very effective sound dampener.


you might want to go to the QuietRock site and read on. Your method offers much less sound deadening and not cheaper. QuietRock is equivalent to 5 layers of 1/2" sheetrock.


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## pyper (Jul 1, 2009)

Bob Mariani said:


> you might want to go to the QuietRock site and read on. Your method offers much less sound deadening and not cheaper. QuietRock is equivalent to 5 layers of 1/2" sheetrock.


5 layers of drywall... in a laboratory setting. It pretty much says right on the home page that it isn't really going to work that well in a real-world application.

Still looks like a pretty good product.

Like I said before though, it doesn't matter if your walls are totally soundproof if the sound has three other ways to get from here to there -- work from the weakest part of the project to the strongest.


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## jerryh3 (Dec 10, 2007)

Bob Mariani said:


> using insulation will help. But overlaying the drywall with QuietRock is by far the best sound deadening method to use.


I don't know if it's "the best" method out there, but it's certainly good. But, at that price it better be. There seems to be a lot of debate of Double drywall/Green Glue vs. Quietrock on the A/V forums.


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## pyper (Jul 1, 2009)

jerryh3 said:


> I don't know if it's "the best" method out there, but it's certainly good. But, at that price it better be. There seems to be a lot of debate of Double drywall/Green Glue vs. Quietrock on the A/V forums.


It's all about the weakest link, which is rarely the wall itself -- much more likely to be the door.


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## jerryh3 (Dec 10, 2007)

pyper said:


> It's all about the weakest link, which is rarely the wall itself -- much more likely to be the door.


True. The first step would be a solid core door with the proper weatherstripping. But, being this is a mechanical room, and as you pointed out, it may need to be vented. And as you also pointed out, a baffled type of vent would probably give the best results.


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## pyper (Jul 1, 2009)

jerryh3 said:


> True. The first step would be a solid core door with the proper weatherstripping. But, being this is a mechanical room, and as you pointed out, it may need to be vented. And as you also pointed out, a baffled type of vent would probably give the best results.



If he can have an outside air supply that would be even better:thumbsup:

I wonder how much of the noise is being transferred from the furnace directly to the basement floor and propogating through the foundation. No amount of wall treatment can mitigate that.


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## jerryh3 (Dec 10, 2007)

pyper said:


> If he can have an outside air supply that would be even better:thumbsup:
> 
> I wonder how much of the noise is being transferred from the furnace directly to the basement floor and propogating through the foundation. No amount of wall treatment can mitigate that.


HVAC isn't really my thing so I'm not sure of the requirements for the venting. I don't think there would be a lot of transfer to the floor. I'm sure most of the noise is from the combustion and blower noise. I'm sure a good door, insulation, and 5/8" drywall would take care of most of the noise, and if not, Green glue and another layer of drywall would take of the rest.


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## Ted White (Jun 23, 2009)

Many good thoughts here. The pre-damped drywall brands mentioned do a great job. These panels are essentially (generally) standard drywall with a bit of damping compound put in between on an assembly line. QuietRock, Supress, ComfortGuard, SoundBreak. All great, and all work.

Better and cheaper to just use really inexpensive standard 5/8" drywall and damp the panels yourself in the field. You can use QuietGlue, Swedak, DecibleDrop or Green Glue. The resulting wall will be heavier (very critical) and likely better damped.


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## BlueBSH (Oct 29, 2009)

pyper said:


> If he can have an outside air supply that would be even better:thumbsup:
> 
> I wonder how much of the noise is being transferred from the furnace directly to the basement floor and propogating through the foundation. No amount of wall treatment can mitigate that.


what do you mean by outside air supply? The furnance right now has its fresh air intake coming in from outside, it has PVC pipe running to the side of the house along with the exhaust going a similar route..


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## Ted White (Jun 23, 2009)

pyper said:


> I wonder how much of the noise is being transferred from the furnace directly to the basement floor and propogating through the foundation. No amount of wall treatment can mitigate that.


That's certainly a consideration. Given the mass of the slab, it's not likely to get excited from the vibration of the fan. Not _likely_, but anything's possible


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## BlueBSH (Oct 29, 2009)

Ted White said:


> That's certainly a consideration. Given the mass of the slab, it's not likely to get excited from the vibration of the fan. Not _likely_, but anything's possible


I think 90% of the noise is transfered in the open air... because in the furance room its loud... go to the next room next to it, its about 70% of the noise... farthest room abou 30%.. upstairs about 10-20%


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## Ted White (Jun 23, 2009)

That's a good bit of data and a good assessment.

In my opinion there's just not enough noise to warrant anything more than drywall. The mass of double drywall will stop a great deal of sound. The trick is sealing the room up. This means any air exchange in and out of that room as well as the door itself. Someone else mentioned this. Maybe pyper. He had nailed some great info.


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## BlueBSH (Oct 29, 2009)

Ted White said:


> That's a good bit of data and a good assessment.
> 
> In my opinion there's just not enough noise to warrant anything more than drywall. The mass of double drywall will stop a great deal of sound. The trick is sealing the room up. This means any air exchange in and out of that room as well as the door itself. Someone else mentioned this. Maybe pyper. He had nailed some great info.


I kind of think if I sub divide that room into two rooms, one where the furnance and water heater are and drywall it up, and maybe have something like a low profile carpet on the floor around the rest of the room (with some space left between it and the furance for fire reasons) it would damper the noise a good bit, the other half of the room now has "extra" carpet laying in it and the noise on that end does damper down some due to the carpet...


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## Ted White (Jun 23, 2009)

Not a bad plan. I think, though, that just sealing the room will do the trick. Any sound waves that are of a low enough energy to be absorbed by that carpet would (generally) have insufficient energy to make it through a sealed wall, especially if made more massive with a second layer of drywall.


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## BlueBSH (Oct 29, 2009)

Ted White said:


> Not a bad plan. I think, though, that just sealing the room will do the trick. Any sound waves that are of a low enough energy to be absorbed by that carpet would (generally) have insufficient energy to make it through a sealed wall, especially if made more massive with a second layer of drywall.


Going to have to run these ideas up against the local code guy and see what comes back as a plan


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## Ted White (Jun 23, 2009)

I suspect the biggest issue is sealing the room. I'm no HVAC guym but most utioity rooms require a slooted door, etc due to the combustion taking place in there. May not be an issue with you, as you have fresh air coming in as part of the air exchange.


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## user1007 (Sep 23, 2009)

Cork is a renewable resource. You might even be able to claim a green credit for using it. It has great natural sound insulating properties perfect to your situation. Libraries and museums have been using it for years for this reason. 

Since this is a utility room, you don't care but it does come in beautiful colors should you ever want to be creative and do a floor. Clients do not always take my advice but any nailed floor I recommend installing comes with a recommendation for a cork underlay layer because of its natural qualities. 

You should probably insulate those walls with something before you put it up. Your local box store will not have it in the thickness and sizes you need to finish a wall but shop online.


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## Ted White (Jun 23, 2009)

Cork is a little soft and a little resilient and essentially does a little. It was used to reduce footfall noise years ago as an underlayment.

Today there are much more effective materials and systems, but the real issue here is that a floor treatment isn't going to help in this fellow's case.


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## user1007 (Sep 23, 2009)

Ted White said:


> Cork is a little soft and a little resilient and essentially does a little. It was used to reduce footfall noise years ago as an underlayment.
> 
> Today there are much more effective materials and systems, but the real issue here is that a floor treatment isn't going to help in this fellow's case.


Was not suggesting a flooring material. I use panels of cork all the time on walls. I get nice, thick 4x8 sheets.


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## Ted White (Jun 23, 2009)

Well, cork on the surface of a wall may help with sound conditioning (reverb) for the sound waves that have insufficient energy to leave the room. Just like the use of foam panels on the walls of a sound room.

For higher energy waves (low frequency bass or high volume mids), lightweight spongy materials just aren't going to do a whole heck of a lot. 

Given that the walls are drywalled and sound is still escaping, we can conclude that the energy of the sound is sufficient to get the walls moving and / or the sound is leaking.

I'm more in the camp of the sound leaking, but sound would likely easily pass through single sheet drywall.

Anything we use for sound isolation (not in-room sound conditioning) has to fall into one of these four buckets:

- Decoupling
- Absorption
- Mass
- Damping

Lightly spongy, lightweight materials can't effectively decouple if deployed on the studs.

Spongy materials are too dense to contribute to cavity resonance absorption.

These materials generally have very low density and mass.

These materials don't damp what thay are in contact with. 

This is why humble drywall really works well. Very low cost, yet great mass.


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## Bob Mariani (Dec 1, 2008)

sdsester said:


> Was not suggesting a flooring material. I use panels of cork all the time on walls. I get nice, thick 4x8 sheets.


this method is used to reduce the sound from bouncing around the room. Usually used in media rooms to retain a pure sound. BUT... it will do nothing to keep the sound from leaving the room which is what the OP is asking for.


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## Ted White (Jun 23, 2009)

Exactly


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