Author Topic: A/C Enclosure  (Read 13097 times)

Vince Bell

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A/C Enclosure
« on: May 11, 2004, 04:47:10 AM »
Hi, I plan on making an "L" shaped enclosure with open top to reduce compressor noise from my HV/AC unit to the rest of the yard.
Two questions:
1) is your MVL weather proof, and how best to attatch it to sound board?
2) where one end of the "L" attaches to the house, will sound now be transmitted into the house?  And what method of attachment/seal would you recomend, if so?


scott swisher

  • Guest
Re: A/C Enclosure
« Reply #1 on: May 18, 2004, 10:22:45 PM »
Hello Vince,

First of all, one of the most difficult things to do is to soundproof the outdoors from the outdoors.

To answer your questions:

1) The MLV is for the most part "weatherproof" if sealed properly.  However, soundboard is not "weatherproof" and therefore you should use CDX exterior plywood.  You can either glue or staple the MLV directly to the CDX.

2) You would want to use an Acoustical Caulking  at the seam where your enclosure attaches to the house.

Additional considerations:

The barrier needs to be at least 8 ft taller than the noise source for maximum effectiveness.

The barrier can have a slanted top to allow for drainage or run off.

This semi enclosure may reflect some of the sound towards the house when it is blocked from dispersing into the yard.

It may be advantageous to include some closed cell foam material  in conjunction with the MLV to both block and absorb noise.

If you have additional questions, regarding making your barrier please give us a call at (888) 942-7723.

Thank you,

BJ Nash
Super Soundproofing Consultant

vince bell

  • Guest
Re: A/C Enclosure
« Reply #2 on: May 21, 2004, 05:07:03 AM »
Thanks so much for the reply.

I'm a bit confused about the plywood, as I read another article on your site about soundproofing a "Generator or other noisy things", and it said: "Plywood is not recommended because wood transmits sound so readily".  It recommended Soundboard, or Homasote?

Is the Homasote also not weatherproof?

I'm trying to reduce sound transfer through an outdoor barrier, (not expecting to eliminate it), as well as reflect much of it into a wooded area.

The A/C unit is right at the corner of the house very near the "wooded area".  The outdoor shaded seating area with view is only about 20' from the A/C unit, unfortunately!

An "L" shaped barrier seems like the only answer as the top of the unit must remain open.

Does the MLV reflect as well as absorb vs. the closed cell foam?  Which does which better?

Any further construction suggestions would be much appreciated.

Again thanks for your input.   :)


Scott Swisher

  • Guest
Re: A/C Enclosure
« Reply #3 on: May 24, 2004, 04:12:55 PM »
Hello Vince,

The exterior plywood would be ok to make your barrier out of because you would be placing a barrier material over it in the MLV Mass Loaded Vinyl.

Best case scenario would be to have an L shaped enclosure made out of sheet metal to your specifications and then to use the closed cell foam material to absorb sound.

The two main principal materials here are MLV for sound blocking ability and closed cell foam for its ability to absorb sound.  The MLV is a superior sound blocker or reflector and the closed cell foam is a superior sound absorber.

To the best of my knowledge, the homasote is not a waterproof material.  Homasote is a board made out of recycled paper materials.


BJ Nash
Super Soundproofing Company

Vince Bell

  • Guest
Re: A/C Enclosure
« Reply #4 on: May 28, 2004, 05:15:38 AM »
Thanks again.

Is the closed cell foam something you sell as well as the MLV, and is it also weatherproof, or will it absorb water?

Is closed cell available in local outlets?

I'm suprised you suggested sheet metal, what gage?

Are we talking double wall with MLV inside, and closed cell facing the noise on the surface of the barrier?

thanks for sticking with it!.   ;D


just a guy

  • Guest
closed cell foam
« Reply #5 on: January 17, 2006, 11:18:25 PM »
hey guys good stuff but you might want to know closed cell foam does not absorb sound. open cell foam absorbs sound by trapping vibrating air molecules in the open cells and converting the energy to heat. you can tell if its open cell if you can blow into it. if not, its acoustically useless. theres a good resource here if you want to look it up:


  • Guest
Re: A/C Enclosure
« Reply #6 on: June 08, 2006, 08:47:55 PM »
This is a coincidence! I just finished plans for an A/C enclosure and am trying to decide what material to use for the soundproofing.  I had priced the pink foam builders use to sheath house walls until I read this great site.  Now I have four questions:
1) Is the pink foam at my building supply store a "closed-cell foam" as referenced in your comments to Vince?  2) Can I use it without the MLV though given it wont be as effective? 3) Do I need to leave ventilation beneath the barrier wall? (I assumed so in order to allow the A/C unit best air flow. I planned to leave 4".) 4) Is the referenced cost of shipping your closed-cell foam a cost per pound or a one price cost?
Thanks in advance for helping!


  • Guest
Re: A/C Enclosure
« Reply #7 on: September 28, 2006, 12:03:54 AM »
Hi Vince Bell,

Air conditioners outside are discussed at in a thorough manner.  You need to have a top on the enclosure as well.  To attach MLV to sound board use heavy duty adhesive and staples.  You can paint the MLV to protect against UV.  To keep sound from being transmitted into house where the "L" attaches use isolation tape.  It is discussed and shown at You always want to decouple any mechanical fasteners when soundproofing.