[Job2Do]

Hello Everyone,

I'm in the process of finishing a home theater room in my basement and I'm running into a few issues with my HVAC returns and I need some advice. I am completely sound proofing the walls and ceiling and the return vent is using the entire joist for the return, so I can't get any sound deadening material installed in the joist. I know usually these returns are calculated to match the supply vents most the time, so I'm not sure if I have any room to move the return vent panning up in the joist a little to allow about 3" of room to put in my Roxul "Safe n' Sound" below the panning? I will list my supply information below with a little detail about my house. If I wasn't able to move the return panning up 3" because the supply to return ratio would be off to much I was wondering about using the joist next to it as part of the return, by adding some holes in the joist (to code). With a 12' joist I could put some 3" holds in the middle of the joist spaced 2" apart. If this would work I would need some type of idea on how many holes would be required. The additional joist would be connected into the return run off the furnace that runs the length of the house. I am not sure if this would be efficient enough to make up for the air flow or not?

The room the return is connected into is my living/kitchen area. The two rooms are connected together with a wall partially separating them. This partial wall is floor to ceiling and may be about 45% in length (Picture Below). There is a hall way connected into the living room that has a return vent (around 30" x 6") that would not be altered since it is in a different area of my basement. No supply vents are in the hall. The two rooms are supplied with three standard size floor supply vents. One in the living room, one in the kitchen, and one between the two rooms. The return vent is located on the partial wall pointing on the living room side. This return vent has an opening of around 30" x 6". It travels down two 16 o.c. stud cavities into the return joist vent in the basement that I want to adjust. The joists are 16 o.c. and 2" x 12". The total square foot of the living/kitchen rooms are around 675 sq. ft. All other rooms on the main floor have their own supply and return.

Below is a picture of the return vent in the basement. Again I am thinking of moving the return pan up 3" if it wouldn't cause any issues in the current ratio of return to supply or moving the return pan up 3" and adding another joist into the return. Any other ideas are welcome as well.


**Picture of home theater room HVAC**
postimg.org/image/r7x9frps5/

**Picture of living/kitchen area**
postimg.org/image/3wnkdcqmp/

My final question is I have another joist panning return in my home theater room that goes nowhere. It probably extends off my return 3 feet into the room and that is all it does. Not sure if it was intended on it going up a wall or anything. I wouldn't image this would be for any volume? Was thinking I could just remove this or move the panning up 3" as well? you can see it in the very back left corner.

Thank you all very much for your time reading through this and any feedback would be greatly appreciated.

 

[Fix'n it]

i can't give much advice. but i have to ask = why do you need it sound proofed ?

 

[Job2Do]

Sound proofing a movie theater room keeps all the sounds isolated within the room. This allows movies to be watched at theater like volume without disturbing the neighbors and keeping the sound from breaching the other parts of the house.

 

[Fix'n it]

yeah, i understand that. are you in a town house or something ?
. and, do you think stuffing the joists with roxul will "sound proof" the room ?

 

[Fix'n it]

far as your return duct goes. can you make a twin of the reduces size duct, in a joist next the the current one ? in other works, make the current duct half size, then make a twin of it in a joist bay next to it.

 

[Job2Do]

I'm in a sub division with houses all around me. I'm putting in a huge $5,000+ surround audio system, so my neighbors wouldn't be to happy with me.

I know using Roxul between the joists wouldn't help 100%. It is just part of the process help isolate the sound. Once the joists are filled with Roxul "Safe n' Sound" I will use resilient channel to decouple the sound. This separates the drywall from resting totally against the studs and makes it harder for the sound to pass through. This process is the most critical part of sound proofing. There are other things involved like solid doors and stuff, but right now I'm just focusing on making sure all my floor joists are filled with Roxul first.

 

[Fix'n it]

so, your in a "house" = not attached to any other building ?

$5000 = 2 nice'ish subs. that would not bother any house neighbors. soundproofing or not.
unless the houses are 3' apart.


btw. i have a HT that most people would consider insane. though it is not to those that "know". its just nice.

 

[Job2Do]

Yes, it is a house and the houses are really close to each other. I have had many different audio systems over the years and have made a lot of neighbors mad (different town) from the bass and stuff, so I know soundproofing is a must for this area. My neighborhood has houses almost stacked on top of each other. My only reason is not related to just the neighbors. I want to be able to keep the sound down throughout the rest of the house. Since the living room is directly above the HT, having a sound proofed room will allow other members of my family to still relax up stairs and watch TV or talk on the phone without hearing the movie scream through the floor. This is the main reason I'm wanting to make sure the floor is filled with Roxul. Right now without I can hear people talking directly under me. I know drywall will help with sound, but not as much as Roxul, resilient channel, and double layer drywall.

I put $5000+ because I haven't picked out all my audio system stuff yet. Just trying to state that the system is going to be loud and it would pierce through the walls. I know my amps along are going to be well over $3,000+ without the speakers. My goal is to be able to watch movies or play video games at late hours of the night and not worry about the chance of me keeping the neighbors up or even members of my family when they are trying to sleep.

Thank you for the FYI though! If I was out in the country and had the movie room in an area of the house that didn't matter I wouldn't care about doing any of this.

 

[Job2Do]

Fix'n it, I just saw your question about the twin duct next to the current one at half the size. That was part of the main question that I was asking above. I am thinking that may be possible, but it would require boring holes (3" w/ 2" separation) in the existing joint to allow the air to transfer over to that joist. I was hoping someone that has some experience with HVAC could help with that answer. I'm not an expert in HVAC, so I don't know all the tricks of the trade. I do know that you have to balance the return and supply. I bought my house from a previous owner, so I'm not aware if the original HVAC installers calculated everything 100% or maybe over calculated the return and I have room to move the duct panning up 3" (about half) or do that and use the other joist to compensate for the loss. Hopefully someone can assist with that answer. Thanks for the suggestion!

 

[beenthere]

You can safely reduce the joist cavity to only 8" high, and still move more air then the wall cavities feeding it can. Could go to only 6" high if needed.

 

[Job2Do]

Thanks for letting me know. I just wanted to make sure I wouldn't have any type of vent whistle or any reduction by reducing the joist return down. This was the information I needed. Thank you for your time!

 

[beenthere]

Your welcome.

 

[Fix'n it]

my idea would not need holes drilled in the joists.

whatever way you do it = check your before and after delta's.

 

[akjose]

Thanks for letting me know. I just wanted to make sure I wouldn't have any type of vent whistle or any reduction by reducing the joist return down. This was the information I needed. Thank you for your time!

You won't hear the whistle with all the noise

If you did the twin duct, could you not add another return grille instead of drilling holes in the joist?


Sent from my iPhone using Tapatalk

 

[sktn77a]

"Soundproofing" will reduce mid and high frequency sound transmission but it will do little to nothing for lower bass energy transmission. If your neighbors complained before, they will still complain!

 

[Bob Sanders]

STKN is absolutely right.
Bass travels in strange ways. I have dual 15" subs in the van and my wife can "feel" the bass when I'm down the street (van windows closed). Can't hear the music, but she "feels" it.

I also have dual 15's on my home theater system and our houses are packed pretty close. My neighbor has told me she clearly knows when we're watching a movie. The vibration carries through the pipework, the concrete, the ground... etc. Not much you can do about though I don't think.... at least not without affecting the movie viewing (the vibration is part of the experience)

 

[Bob Sanders]

You won't hear the whistle with all the noise

Surround sound relies heavily on dynamics. In other words, sure there are loud portions, but there are also soft portions too and it's those times when you can clearly hear the vent noise.

If I wasn't so lazy I would probably connect the furnace blower through relay to the movie theater in some fashion which would lock the blower into its lowest speed for the duration of the movie.