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+-- Thread: Soundproofing a large closet with HVAC inside. (/showthread.php?tid=7325606)
RE: Soundproofing a large closet with HVAC inside. - daddo - 11-29-2016
When trying to reduce sound, remember that a hard dense surface is used to reduce sound transfer through it and reflect the sound away and softer surfaces are used to absorb sound and help prevent reflecting it.
RE: Soundproofing a large closet with HVAC inside. - frule - 11-30-2016
I wonder if 1" blue/pink foamboard would be a good soundproofer?
RE: Soundproofing a large closet with HVAC inside. - daddo - 11-30-2016
Basically, if it's fireproof- you can use it.
RE: Soundproofing a large closet with HVAC inside. - Cooler - 11-30-2016
The Google search you want to make is "sound attenuating building materials". I doubt you will find foam building panels in that search.
There is a bit of science involved. It involves harmonics, vibration, sound absorption, etc.
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=sound+attenuation+building+materials
This article, published by HUD, a US government agency is pretty good at explaining the whole thing: https://www.hudexchange.info/onecpd/assets/File/Noise-Guidebook-Chapter-4-Supplement.pdf
Basically you want to minimize resonance, and sound reflection, and you want to include sound absorbing materials.
I watched with amusement a home improvement show where they were building a practice room for a band inside a garage. They covered the interior of the garage with convoluted foam. This is exactly the wrong way to go about this.
They should have built a room within the garage not attached at any point to the garage walls or ceiling (the concrete floor can be shared). They should have used ceramic tiles on the interior of the practice room.
They should have used the staggered stud arrangement to isolate the interior and exterior walls and prevent transmission of vibrations.
And they should have put the convoluted foam on the interior of the garage walls if needed (I doubt that it would have been needed).
The reason that the show's approach was all wrong is that the band wants to play at a sound level that approximates a stage performance. The convoluted foam on the interior walls means that they would have to play louder than normal to achieve that sound level.
But if they had lined the interior with ceramic tiles, it would be like singing in the shower. The sound would get reflected all around and seem louder than normal. So they would be able to achieve the perceived sound levels at a much lower actual sound level. The ceramic tile would add density to the walls reducing vibrations, and the isolated room would reduce sound transmission.
So you need to think this through entirely.
Putting a second layer of sheetrock may be sufficient to minimize the drum head quality of the single layer of sheetrock. Sound reflects like an image on a mirror. So you need a non-reflective material (convoluted foam is the most effective).
I would get some convoluted foam and glue it to 1/4" thick ply and hang the panels from the ceiling with wires. Leave a little space between the wall and the panel. Do this on the rear and sides. That might be sufficient to achieve your requirements. Make sure the convoluted foam is fire rated.
These are about $2.00 per square foot, and come in 12" x 12" panels; they look pretty cool too. Fire rated : https://www.amazon.com/12-Acoustic-Panels-Studio-Wedges/dp/B00U3ZIAUE/ref=sr_1_10?s=musical-instruments&ie=UTF8&qid=1480514897&sr=1-10-spons&keywords=B00MAQ97AQ%7Csewell+foam&psc=1
RE: Soundproofing a large closet with HVAC inside. - TDKPE - 11-30-2016
When I built my basement office, I used RC-1 resilient channel to isolate the ceiling drywall from the joists. I also used FG insulation batts, but that was for thermal insulation, both walls and ceiling. That stuff will do virtually nothing for sound.
The RC-1 puts compliance between the framing and the giant diaphragm of drywall. And it worked far better than I expected. And it's cheap, and easier to do than staggered studs, and only adds 1/2" to the wall thickness, if memory serves. I can play my big audio system at annoying levels, and while I can hear it in the room above, it doesn't even interfere with TV or other activities. And I usually listen at lower levels anyway.
Since it's the inside of an enclosure, the taping doesn't have to be pretty. And you can stack a double layer of drywall.
And do seal the door, as others have strongly suggested. The tiniest crack admits a LOT of sound.
Sealing is, of course, dependent on a sealed system (intake and exhaust, usually through a side wall), or a separate combustion air inlet from outdoors.
RE: Soundproofing a large closet with HVAC inside. - Snipe Hunter - 12-01-2016
(11-30-2016, 05:02 AM)frule Wrote: I wonder if 1" blue/pink foamboard would be a good soundproofer?
no
RE: Soundproofing a large closet with HVAC inside. - daddo - 12-01-2016
We had our walls in this old house filled with cellulose insulation. It freaked the kids out because the house became so quiet! However, just one extra sheet of 1/2" sheetrock with a space would probably do the same thing.
RE: Soundproofing a large closet with HVAC inside. - frule - 12-02-2016
Still going to consult with HVAC company, but it looks like spaced sheet-rock will be the answer.
Fred
RE: Soundproofing a large closet with HVAC inside. - Splinter Puller - 12-02-2016
(12-02-2016, 06:54 AM)frule Wrote: Still going to consult with HVAC company, but it looks like spaced sheet-rock will be the answer.
Fred
Don't forget the doors. If the existing doors are hollow core think of them as a reverberating drum that lets the sound right through. They need to be solid and sealed (sound gasketed) for sound mitigation. Otherwise, any wall fixes are like leaving a hole in the fix. The three solutions to sound problems. Mass, Distance and air tightness. You're closet solution can only use Mass and Air tightness. Mass (extra drywall and solid doors) convert sound into heat and air tightness... (filling any holes and sealing the door edges) prevent sound from bypassing the masses. Distance... moving the noise further away is probably not workable
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RE: Soundproofing a large closet with HVAC inside. - BrokenOlMarine - 12-05-2016
We had been in our home about fifteen years when the AC died. When we replaced the AC they had to tear out portions of the duct work in the Furnace closet to install some of the control works for the new AC unit and we asked if it wouldn't be wise to replace the Furnace at the same time. (We had asked this same question of all the bidders on the job.) They all said that the furnace could last another ten years, or go next year. Since labor was a large portion of the job, we decided to go with replacing it at the same time, and went with the OEM unit. BIG mistake. We saved about 30% over the next bid, but..... (Replacing the 15 year old unit wasn't a mistake, the new unit was more efficient and saved propane in the long run... but)
When they fired up the new unit it sounded like a 747 taking off. I called the owner of the company and he sent his "boys" back out. They made some "adjustments" and it was certainly quieter. Funny, but it was no longer cooling. (Seems they overrode the system and prevented the three speed fan from going into HIGH.) They came BACK out and reset the system to run at all three speeds and told me that they could order another FAN... at about $400. The savings on the OEM system was accomplished in a variety of ways, but one way was to use a CHEAP blower motor / fan assembly. The assembly has cheap bearings and very few of them and rumbles when it turns. The fan blades are not the best in the market and are themselves noisy. The motor and fan blades vibrate and that is transmitted through the metal closet it's mounted in and thru the duct work. If you replace the fan, it will make a huge difference. They put some silver insulation on the duct work behind the motor and it made a small difference, but they re-emphasized, if you really want to lower the decibel level, upgrade to a high end blower/fan assembly.
We haven't done it yet, just haven't gotten around to it. Really need to. When the heat/ac cuts in, you have to turn the TV up loud. When it cuts out, you have to turn it back down. You watch tv with a remote in your hand.
Ask your HVAC guy if you have a low end assembly in your unit. Perhaps replacing that will make a big difference and you won't have to insulate?
I can tell you that before we replaced the old system, we never had this issue.
