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post #1591 of 3163 Old 08-08-2016, 01:21 PM
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I would add that LED lights run far cooler than incandescencents and overheating them within a backer box is much less problematical.


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post #1592 of 3163 Old 08-08-2016, 01:52 PM
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I would add that LED lights run far cooler than incandescencents and overheating them within a backer box is much less problematical.
Agreed. Should be a non-issue.

Most of the LED lights now have auto-shut off @ 60°C, and the A/C wire should be 90°C+ rated.

OP wanted to know if he can circumvent the manufacturer's requirements on air-space around the luminary. I'd bet he'll be fine but it seems wise to perform a bench-test first and see how it performs.

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post #1593 of 3163 Old 08-15-2016, 07:07 AM
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Quick question for you guys. How effective would it be to run a piece of drywall on an angle from the bottom of a joist to the top of the one next to it? A friend sent me a pic of that asking if it was any good, we are pretty sure its only the drywall, nothing in the space behind it. I am no expert, but it seems like if it was that easy a lot of you guys here would do something similar. So how effective could something like that actually be?


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post #1594 of 3163 Old 08-15-2016, 08:01 AM
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Originally Posted by Broke EF View Post
Quick question for you guys. How effective would it be to run a piece of drywall on an angle from the bottom of a joist to the top of the one next to it? A friend sent me a pic of that asking if it was any good, we are pretty sure its only the drywall, nothing in the space behind it. I am no expert, but it seems like if it was that easy a lot of you guys here would do something similar. So how effective could something like that actually be?


Thanks,
Sean
I would think this would likely create a triple leaf effect, which actually decreases effectiveness. Triple leaf is when there are three separate 'masses' with air space separating the masses. If you have the theater ceiling DW (Double DW with GG), that is 'one mass', the 'angled DW' becomes a second 'mass' as it isn't directly connected, and then the OSB subfloor (and flooring above), is a 3rd mass... thus, possible triple leaf effect. I have seen most of this in the context of three parallel masses vs an angle, but I would personally steer clear of it.

The 'gold standard' of sorts, is putting Green Glue & DW (an a second GG & DW layer) directly on the sub-floor, flat against the OSB sub-floor. This is a 'single mass'... the flooring above/osb sub-floor/GG-DW/GG-DW are all virtually 'one piece'... The theater ceiling construction is then a second mass... so, only two 'masses', and thus, no triple leaf effect.
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post #1595 of 3163 Old 08-15-2016, 08:07 AM
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Originally Posted by kmhvball View Post
I would think this would likely create a triple leaf effect, which actually decreases effectiveness. Triple leaf is when there are three separate 'masses' with air space separating the masses. If you have the theater ceiling DW (Double DW with GG), that is 'one mass', the 'angled DW' becomes a second 'mass' as it isn't directly connected, and then the OSB subfloor (and flooring above), is a 3rd mass... thus, possible triple leaf effect. I have seen most of this in the context of three parallel masses vs an angle, but I would personally steer clear of it.

The 'gold standard' of sorts, is putting Green Glue & DW (an a second GG & DW layer) directly on the sub-floor, flat against the OSB sub-floor. This is a 'single mass'... the flooring above/osb sub-floor/GG-DW/GG-DW are all virtually 'one piece'... The theater ceiling construction is then a second mass... so, only two 'masses', and thus, no triple leaf effect.
Thanks for the response! Judging from the photo he shared it looks like they were going with that angled drywall then just regular old drywall against the joist under that. All of which seems pretty ineffective at best to me.

I did tell him, and show him the standard practice and said that if something like what he sent was effective I doubt everyone would do so much more work for the standard setup.

Also, just to clarify, no OSB in this house! It is about 140 years old, built by his great grandfather and stayed in the family. He bought it from his Mom recently and gutted it down to the studs to modernize all of the HVAC, plumbing, and electrical. He must have seen that pic somewhere and was asking if it was actually useful. You can follow his house on instagram at thehouseonwood.


Sean

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post #1596 of 3163 Old 08-15-2016, 08:26 AM
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Originally Posted by Broke EF View Post
How effective would it be to run a piece of drywall on an angle from the bottom of a joist to the top of the one next to it? A friend sent me a pic of that asking if it was any good, we are pretty sure its only the drywall, nothing in the space behind it.
Sean,

In general, I'd second what Kmhvball stated. However, you left out details (though based on your follow-up post it sounds like Kmhvball may be on the right track in terms of envisioning what you're talking about).

A photo would go a long way to be sure we all understand the question thoroughly. Or a diagram. For instance, when you say "joist," are you talking about a ceiling joist? If so, what is above the ceiling joist?

If the scenario is a 2nd floor room with an attic above it, the issues Kmhvball mentioned ought to be less pronounced, but I agree with him there's very little point in taking your suggested approach even if that's the case. Your friend's approach is more likely to cause problems vs. fix them.

What is his rationale behind the proposed drywalling method? What is he trying to accomplish and why did he arrive at that concept? Is there some reason he can't do 2x layers of drywall on the ceiling? Even without GreenGlue, QuietGlue, etc., the extra mass would be helpful. What are the joists made of and what are their dimensions? Which floor of the house? What is above/below the room?

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post #1597 of 3163 Old 08-15-2016, 08:49 AM
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Sean,

In general, I'd second what Kmhvball stated. However, you left out details (though based on your follow-up post it sounds like Kmhvball may be on the right track in terms of envisioning what you're talking about).

A photo would go a long way to be sure we all understand the question thoroughly. Or a diagram. For instance, when you say "joist," are you talking about a ceiling joist? If so, what is above the ceiling joist?

If the scenario is a 2nd floor room with an attic above it, the issues Kmhvball mentioned ought to be less pronounced, but I agree with him there's very little point in taking your suggested approach even if that's the case. Your friend's approach is more likely to cause problems vs. fix them.

What is his rationale behind the proposed drywalling method? What is he trying to accomplish and why did he arrive at that concept? Is there some reason he can't do 2x layers of drywall on the ceiling? Even without GreenGlue, QuietGlue, etc., the extra mass would be helpful. What are the joists made of and what are their dimensions? Which floor of the house? What is above/below the room?

Again, thank you for the response.

Because it was posted on instagram, its not really easy to get a pic to post. This was the best I could do.

This was the one he sent me


And this was the next photo


Both of these photos are from down.to.the.studs on instagram.

So this is NOT my friends house, just a photo that he found and sent over to me asking how effective that method is. I don't have any of the details you are asking about for the pictures posted. As far as my friends house all of those details vary pretty greatly depending on where in the house we are talking about. Some are 2x10 (actually 2" x 10", not like current 2x10's) with just a layer of hardwood above. I don't believe there is any subfloor anywhere, but I would have to clarify. For the third floor he is replacing the 2x4's with 2x10's so that the floor is more stable/usable. I was up there when it was just the hardwood over 2x4 and it was a bit too bouncy for my taste

Like I said, he hasn't done anything yet. He was more curious if that would be effective since it would be very easy for him to do at the current stage. He can just as easily do drywall with GG or something similar, but that is a lot of time and cost to do the whole house like that vs just throwing up some drywall on an angle.


Sean
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post #1598 of 3163 Old 08-15-2016, 09:09 AM
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Thanks. That helps.

If he's seriously considering that route, your best bet is to get input from one of the audio or sound-proofing experts such as Bryan Pape (@bpape;)or Ted White (@Ted White;).

Generally speaking, I wouldn't do it. I'd go with the validated concept of 2x drywall sheets, or a material combo such as OSB+Drywall, and I'd also focus on the sub-floor for any room(s) above it.

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post #1599 of 3163 Old 08-15-2016, 09:14 AM
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When building a room within a room, the obvious goal is to not mechanically link the framing of the theatre to the framing of the rest of the house. However, since both are connected to the concrete foundation, what's the consensus on having the framing of the theater right against the short wall of concrete?

Not the 10 foot wall mind you, but there is a foot of concrete where the floor was dropped, and the sill plate of the load bearing wall sits ontop of. I'll go and take pictures to illustrate my question. If I jut it up against that short wall, I still have 2.5 inches of space between both frames.

Also, what do people do about vapor barriers underneath frame? Am I to apply acoustic sealant to the vapor barrier? Or is it useless at that point... basically how do you work around that 6mm vapor barrier underneath the frame?

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post #1600 of 3163 Old 08-15-2016, 08:57 PM
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When building a room within a room, the obvious goal is to not mechanically link the framing of the theatre to the framing of the rest of the house. However, since both are connected to the concrete foundation, what's the consensus on having the framing of the theater right against the short wall of concrete?
Amit,

I appreciate you going to the trouble to upload pictures. It makes it much clearer with regards to your question.

Ideally, you want a small separation from the concrete wall. However, your concrete wall is so short, if you don't have separation... it's not end of the world. That said, I would suggest you start framing your "room within a room" ~3.5" from the stud walls shown, so that you're 'inside' wall is off the concrete.

Quote:
Also, what do people do about vapor barriers underneath frame? Am I to apply acoustic sealant to the vapor barrier? Or is it useless at that point... basically how do you work around that 6mm vapor barrier underneath the frame?
In the U.S., ordinarily pressure-treated lumber is used in place of a barrier+kiln dried wood. In your case, as you mentioned there is a barrier but this is actually a moisture barrier, not a vapor barrier. Concrete will allow moisture to pass through it, but wood doesn't like moisture, which is why the barrier was placed there by your builder. Technically, a physical moisture barrier should provide superior protection vs. treated wood.

When adding new wall framing for a room-within-a-room build out, if it's in a basement (which your future room obviously is), you need to follow the same rules. In your case, I would do what the builder did. Get yourself some good 6mm poly sheeting to place under the framing. Basically, replicate what your home builder did. Your best will likely be a building supply store (i.e. not the big box stores such as Home Depot... though Menard's is better than most from what I've heard, if you have any nearby).

You may also need a vapor barrier up against any exterior walls (or you might not if they're de-coupled). For that, you should consult your local building codes to determine what is recommended for below-grade exterior walls.

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post #1601 of 3163 Old 08-20-2016, 07:23 AM
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I'm rebuilding my house and have a soundproofing question. I was thinking of adding DD with GG in between the floor joist for better sound proofing in my theater/game room. The framing of the house is done and I have a lot of extra Rim Joist. They are about 1" thick. Could i just put this between the joist? From what i understand the best soundproofing has to do with adding mass. So maybe this would help.

Thanks
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post #1602 of 3163 Old 08-21-2016, 06:42 PM
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I'm rebuilding my house and have a soundproofing question. I was thinking of adding DD with GG in between the floor joist for better sound proofing in my theater/game room. The framing of the house is done and I have a lot of extra Rim Joist. They are about 1" thick. Could i just put this between the joist? From what i understand the best soundproofing has to do with adding mass. So maybe this would help.
Actually, the best soundproofing methods have to do with de-coupling first, mass second. Combining both is ideal.

That aside, I'm a bit confused by your post. Are you considering applying DD/GG combo vertically to the rim joists, between each of the floor joists?

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post #1603 of 3163 Old 08-22-2016, 12:16 PM
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I was going to cut strips of drywall and screws them between the the joist to the floor above. Then add GG and then another piece of drywall.

Then for the theatre ceiling I was going to use resilient channel and then DD with GG.
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post #1604 of 3163 Old 08-22-2016, 11:53 PM
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Amit,

I appreciate you going to the trouble to upload pictures. It makes it much clearer with regards to your question.

Ideally, you want a small separation from the concrete wall. However, your concrete wall is so short, if you don't have separation... it's not end of the world. That said, I would suggest you start framing your "room within a room" ~3.5" from the stud walls shown, so that you're 'inside' wall is off the concrete.



In the U.S., ordinarily pressure-treated lumber is used in place of a barrier+kiln dried wood. In your case, as you mentioned there is a barrier but this is actually a moisture barrier, not a vapor barrier. Concrete will allow moisture to pass through it, but wood doesn't like moisture, which is why the barrier was placed there by your builder. Technically, a physical moisture barrier should provide superior protection vs. treated wood.

When adding new wall framing for a room-within-a-room build out, if it's in a basement (which your future room obviously is), you need to follow the same rules. In your case, I would do what the builder did. Get yourself some good 6mm poly sheeting to place under the framing. Basically, replicate what your home builder did. Your best will likely be a building supply store (i.e. not the big box stores such as Home Depot... though Menard's is better than most from what I've heard, if you have any nearby).

You may also need a vapor barrier up against any exterior walls (or you might not if they're de-coupled). For that, you should consult your local building codes to determine what is recommended for below-grade exterior walls.
Sweet, thanks so much. That's what I ended up doing. Leaving about an inch or so off the concrete. With that done, I can start worrying about the supply/returns. Contractor thought I was out of my mind to ask for something bigger than 4 inch flex ducts (one return/one supply). Finally caved and gave me 8 inch supply and return to the outside. He assured me that cycling it with the outside will work just as well though advised I get a heater.

Now I'm a little concerned about door... my two door openings have almost a 4-6 inch (I'll have to measure to get a precise reading) gap between them. At this point I imagine it's communicating doors or bust. Do I just leave that cavity open? I imagine going through all that trouble only to couple the two door frames would do a lot of harm.
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post #1605 of 3163 Old 08-23-2016, 04:42 AM
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With that done, I can start worrying about the supply/returns. Contractor thought I was out of my mind to ask for something bigger than 4 inch flex ducts (one return/one supply). Finally caved and gave me 8 inch supply and return to the outside. He assured me that cycling it with the outside will work just as well though advised I get a heater.
I'm confused by your statements above. Are you planning to circulate fresh air only, like a dead vent? Or will you install a mini-split HVAC system? Bringing unconditioned air into your HT room is generally unadvised. The exhaust may not be an issue, but you will bring humidity into the room (when present) from the outside. It also can create a flanking path for sound in/out of the theater, depending on how your ducts are routed and what they're made of (i.e. metal vs. flex).

What is your rationale for not simply adding a trunk from your HVAC system to the room? It's just as much work.


Quote:
Now I'm a little concerned about door... my two door openings have almost a 4-6 inch (I'll have to measure to get a precise reading) gap between them. At this point I imagine it's communicating doors or bust. Do I just leave that cavity open? I imagine going through all that trouble only to couple the two door frames would do a lot of harm.
You're talking about space between the original door framing and where you will create a new door frame in your double-stud wall setup, correct? There are a number of possible solutions. The best route is to use a custom-made frame. If you DIY it, you will want to take your time and verifying measurements and making sure you fully understand all the parts. It's not a huge amount of work, just a bit detailed. Or you could get a millwork company to make one for you. In the case of the latter, you would need to provide them with a drawing (can be a rough one) with accurate dimensions of your opening, so they can figure out the details for you.

The most important thing to keep in mind with a custom door frame is sound will leak out around the door unless you use specially designed door seals - such as those produced by Zero Noise. You will need to factor the size/dimensions of these seals into your other door frame measurements. Standard door framing practices will not produce the desired result in sound containment.

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post #1606 of 3163 Old 08-23-2016, 09:22 AM
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I was planning on using flex duct and running it in a soffit with a duct boot. So I imagine flanking would be similar to if I had done the same but hooked it up to the HVAC in the rest of the house.

He was adamant that I would not be able to use that big of a duct if I had connected it to the HRV that the rest of the house was connected to.

To be honest, he wasn't even taking into account how many people or how much heat would be generated in this room. Which has me a bit wary about what he's thinking.

EDIT: Adding more info, the rest is connected to a HRV. The specialist told us that he wouldn't be able to do more than 4 or 5 inch ducts from that to the theatre room. I can't tell if he meant in terms of pressure or capacity.

EDIT EDIT: Or am I totally thinking about it in the wrong way. Allow him to size the duct to the theatre but I size the transition to a larger size (essentially let him calculate the volumetric needs) By using a larger size, I slow down the river in the open area which then opens into a duct boot.

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post #1607 of 3163 Old 08-23-2016, 02:02 PM
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I was planning on using flex duct and running it in a soffit with a duct boot. So I imagine flanking would be similar to if I had done the same but hooked it up to the HVAC in the rest of the house.
Generally speaking, that should be the case, yes.

Quote:
He was adamant that I would not be able to use that big of a duct if I had connected it to the HRV that the rest of the house was connected to.

To be honest, he wasn't even taking into account how many people or how much heat would be generated in this room. Which has me a bit wary about what he's thinking.

EDIT: Adding more info, the rest is connected to a HRV. The specialist told us that he wouldn't be able to do more than 4 or 5 inch ducts from that to the theatre room. I can't tell if he meant in terms of pressure or capacity.
Could be either one, or both. Did he say anything about reaching a point where your system would require a larger capacity unit due to adding on your HT room?

Higher CFM (volume) into a room can only happen with either a larger duct and/or higher velocity. If he meant your system's velocity would drop off to a point that he thought would be insufficient, that could be a good thing for a HT room, since in this case you want a lower velocity so that would be a good thing.

My suspicion is he's thinking the issue is both capacity and velocity, unless as I said he was simply thinking the velocity would be too low. HVAC technicians have tables for FPM (velocity in the U.S.) and they tend to think it's a problem when the figures don't reach those levels or higher, but as I said we want lower FPM in the case of a dedicated HT room.


Quote:
EDIT EDIT: Or am I totally thinking about it in the wrong way. Allow him to size the duct to the theatre but I size the transition to a larger size (essentially let him calculate the volumetric needs) By using a larger size, I slow down the river in the open area which then opens into a duct boot.
That would solve noise and velocity issues, but not capacity (CFM) into the room. Starting with a 5" wide duct you won't get much air through (CFM).

How many 5" register vents are we talking about? If more than 1, do they feed off a larger trunk? What is the diameter of the flex duct coming off the air handler to your room, before it splits into 1 or more registers? Was his suggestion 5" for that?

You also need to ensure there is equal air pushed in (supply) and pulled out (return), so the pressure in the room is equalized. This is particularly true with an isolated, sound-proofed room that is designed to be as air-tight as possible.

BTW, a mini-split system would solve all these issues. Food for thought.

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EDIT: Adding more info, the rest is connected to a HRV. The specialist told us that he wouldn't be able to do more than 4 or 5 inch ducts from that to the theatre room. I can't tell if he meant in terms of pressure or capacity.
What do you anticipate will be the cubic volume of the room when completed? Or alternatively, what do you anticipate will be it's completed dimensions?

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post #1609 of 3163 Old 08-23-2016, 02:44 PM
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Could be either one, or both. Did he say anything about reaching a point where your system would require a larger capacity unit due to adding on your HT room?
He never directly said it, but he hinted a few times that it was too small for what I wanted to do. However, I'm going to give him a call and ask him how much air he was planning on supplying the room. If I'm happy with the amount, then it's just a matter of figuring out how to slow that supply down. That should be down to duct size in the theatre right? Changing the duct size near the end of the run should not have any ill repercussions.

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Originally Posted by HT Geek View Post

Higher CFM (volume) into a room can only happen with either a larger duct and/or higher velocity. If he meant your system's velocity would drop off to a point that he thought would be insufficient, that could be a good thing for a HT room, since in this case you want a lower velocity so that would be a good thing.

My suspicion is he's thinking the issue is both capacity and velocity, unless as I said he was simply thinking the velocity would be too low. HVAC technicians have tables for FPM (velocity in the U.S.) and they tend to think it's a problem when the figures don't reach those levels or higher, but as I said we want lower FPM in the case of a dedicated HT room.




That would solve noise and velocity issues, but not capacity (CFM) into the room. Starting with a 5" wide duct you won't get much air through (CFM).

How many 5" register vents are we talking about? If more than 1, do they feed off a larger trunk? What is the diameter of the flex duct coming off the air handler to your room, before it splits into 1 or more registers? Was his suggestion 5" for that?
His suggestion was just 1. So one 5" return, one 5" supply. Currently I'm not sure because he was merely doing a walk through as our framing had just been completed.

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Originally Posted by HT Geek View Post

You also need to ensure there is equal air pushed in (supply) and pulled out (return), so the pressure in the room is equalized. This is particularly true with an isolated, sound-proofed room that is designed to be as air-tight as possible.

BTW, a mini-split system would solve all these issues. Food for thought.
A mini-split air conditioning unit? Maybe it's the end of a long day, but I don't quite follow. An split AC unit would replace the need for any return and supplies? (sneak edit, just realised how dumb I sound. Of course there needs to be fresh air lol)

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What do you anticipate will be the cubic volume of the room when completed? Or alternatively, what do you anticipate will be it's completed dimensions?
Currently, it's sitting at 163" x 294" x 108". Approx 3000 cubic feet. Minus riser and stage, it should settle down to around 2750.

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post #1610 of 3163 Old 08-23-2016, 04:44 PM
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He never directly said it, but he hinted a few times that it was too small for what I wanted to do. However, I'm going to give him a call and ask him how much air he was planning on supplying the room. If I'm happy with the amount, then it's just a matter of figuring out how to slow that supply down. That should be down to duct size in the theatre right? Changing the duct size near the end of the run should not have any ill repercussions.
Reducing air velocity is a matter of spreading out the area over which the air travels before it enters the room. You can do this with a larger/wider face opening, longer duct work, or going to wider flex duct before it enters the room. Many people use a combination of the above, depending on whatever constraints you have in your room. HOWEVER....

Quote:
His suggestion was just 1. So one 5" return, one 5" supply....

... Currently, it's sitting at 163" x 294" x 108". Approx 3000 cubic feet. Minus riser and stage, it should settle down to around 2750.
FWIW, I suggest you find another HVAC person. This guy doesn't understand what you're trying to accomplish.

First off, a single 5" supply for 3,000 cubic feet is way too small (IMHO). A 5" round flex duct will transfer 80 CFM. That works out to 4,800 cubic feet per hour or 1.75 room changes per hour. Way too little. I would bet you will feel like the room is stuffy with that little air flow. The recommended range is 6-10 room changes per hour. So, to get that level you would need ~16,500 cubic feet per hour at a minimum, or 275 CFM. You would need a 9" duct to reach that level (9" flex duct = 300 CFM).

HVAC technicians are accustomed to looking up desirable CFM values based on the use-case scenario of a given room, but as you may imagine, HT rooms are not on that list.

They're also typically trying to get the airflow to some particular velocity (often 600 FPM or higher). If you tell them you want velocity below 250 FPM, that could make a difference in their suggestion if they can figure out the math. However, I think it's easier to just tell them you want 300 CFM airflow and you don't give a crap about the velocity (FPM)!

Then it's just a question of them calculating if the load on the system is capable of providing that CFM level, in conjunction with the demands on it in other parts of the home. If this is a brand new home, chances are good that your HVAC system is undersized to begin with (hate to tell you that... but it is a common problem with home builders).


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A mini-split air conditioning unit? Maybe it's the end of a long day, but I don't quite follow. An split AC unit would replace the need for any return and supplies?
It may have a supply and return (depends on type). It's basically a small, self-contained HVAC unit where the evaporator and air handler are a single unit. They can be ductless (requires a fairly obtrusive wall mounted unit) or ducted (more sophisticated units).

They are designed for smaller spaces. Very common in Europe. Mitsubishi is prolly the most well known brand.

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One more thing... if velocity becomes a problem... install an in-line fan: problem solved.

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One more thing... if velocity becomes a problem... install an in-line fan: problem solved.
Sweet, thanks for all the help, been spending all day with this and I felt like I was like running around in circles. You've been an immense help today.

If money was no option, I think using a separate HRV combined with a ductless AC split would be the best way to go about this. Most likely will rough in the AC and then tackle the Ventilation part of HVAC first.

The HRV will take care of fresh air, while the AC will act to cool and dehumidify.

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post #1613 of 3163 Old 08-24-2016, 04:40 PM
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What's the difference in performance between clips/channel and a floating joist ceiling? Particularly at attenuating bass? I think it'd be a lot easier to do clips on my ceiling, but would consider joists if the gains were large enough.
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post #1614 of 3163 Old 08-24-2016, 05:01 PM
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Hello All,

I'm debating the sound-proofing measures that would be wise for my room. I have a build thread, but I haven't updated it in a long time (Diablo Theater).

My theater room has a window and a large french door that goes to a patio under the deck. The theater is under the living room.


Room Pictures:
Looking towards window and doors:

Looking towards screen location with room entrance at right:


I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood). If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.

I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?

Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).


Thanks!
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The most critical element in sound proofing is isolation, so I'd suggest isolating the theater ceiling with hat channel and isolation clips, following by DD and green glue. The only superior method I'm aware of is specially designed sound proofing springs, which I would assume are prohibitively expensive. Best of luck!


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post #1616 of 3163 Old 08-25-2016, 04:08 AM
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Quote:
Originally Posted by wingm8 View Post
I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood). If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.

I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?

Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).

Thanks!
I think it looks like a Triple Leaf situation. It looks like there is plywood/some type of sheet product, between the 2x6 wall and the added 2x4 wall. When you add drywall to the outer sides of the 2x6 and 2x4 walls, you'll have 'three masses'... the two outer drywall, and then the inner plywoodish looking sheet. Is that sheeting required as part of the 'Sheer wall'? Could it be on the other side of the 2x6? I did a layer of OSB & a layer of DW on my walls... so, maybe it it could be on the other side and needs to be plywood/OSB, that could just be the first layer.

In my current house basement, I have three different 'ceiling' structures:
1) Theater room: GG/DW/GG/DW on sub-floor, insulation, clips & channel, DW/GG/DW on the ceiling

2) Basement BR (under Master BR): GG/DW, insulation, clips & channel, DW/GG/DW on ceiling

3) balance of basement: Insulation, Clips & Channel, single DW

I do think that even in the balance of basement, that I get a 'benefit', in terms of both limiting some sound going up, and definitely from sound above coming into that area. I even have an open stair well from 1st floor into the basement, and still feel I get some benefit from this very basic effort. I am comparing to my old house, where I didn't have any insulation or clips/channel, and could hear footsteps & the tv from above a lot more.

Certainly the windows/french doors (into theater and out side) will compromise sound containment, but I would still be inclined to do what you can. My electric panel is on my theater front wall, and therefore there is a large 'hole' in my soundproofing, and I am still VERY pleased with my soundproofing efforts. So, if you are looking for "Perfection", maybe it is all or none... but my $0.02, having done a single effort at sound proofing (i.e., not a lot of experience), is that you can still get benefit by doing some.
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post #1617 of 3163 Old 08-25-2016, 05:30 AM
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Quote:
Originally Posted by wingm8 View Post
I'm not too concerned about sound reaching the bedrooms since the theater is on the opposite site of the house. Sound going directly upstairs and outside is more of a concern as well as sound coming in (not too worried about that though, very quiet neighborhood).
Do your neighbors use lawnmowers, have dogs, occasional parties outside, drive a motorcycle, etc.??? They may not be as quiet as you think.


Quote:
If some sound goes upstairs, I'm not too worried, since I'll be in the theater anyway. The theater is partially subterranean, which might help some with the sound reaching the neighbors. The wall facing the neighbors two walls (one 2x4 wall and then a wall that is 2x6 on top of a block wall). That should help cut down sound transmission I hope.
Those concrete block walls will be good for your neighbors but bad for you; they will reflect sound back into the room. Furthermore, sound will behave differently along the portion where the concrete block is not present (on same walls).

Quote:
I was thinking originally of doing DD+GG on the ceiling, but many experts here have stated a half-way solution is no solution at all. I'm not sure that going all-in on the soundproofing will even be worth it with the window and large french door anyway. Can someone let me know their thoughts on my situation?
I would do clips and channel on the ceiling at a minimum. You can deal with the french door and window most efficiently by sealing them off when you soundproof the room (if that is an option), or using a plug in the case of the window. Your best bet would be to build an inner stud wall in front of them to give you plenty of space for isolation. Another (perhaps more efficient) option would be clips & channel.

Everyone's situation is unique, and their tolerance for extra effort and budget is unique, and their desired outcome. That said, I would definitely do clips and channel on the ceiling as a minimum. Any basement theater really needs that or you're going to have sound transmission in both directions (from whatever is going on above into the theater room and from inside the HT room out). The flooring and framing above your room will conduct sound all over, not just up and down. Sound travels remarkably well across wood studs.

Now, in my case I have a 2nd floor HT room above my garage and with an attic above the room. For my ceiling, I chose to do OSB+DD in the middle and a DD soffit around the perimeter. I chose not to use clips and channel and secure my room-within-a-room double stud walls to the ceiling joists. It was a calculated decision based on cost, effort, and perceived gain of using clips versus not using them. Time will tell if it was a wise choice or not, but in my case the potential downside is limited by my future use of the HT room and the home environment. The attic above is pretty big, so there's lots of air to help dampen the HT room noise (plus the mass on the ceiling, plus tons of insulation above the room). Even though that's the case, I am aware of joists in the ceiling that are horizontal toward the one room (a bedroom) that shares a wall with the HT room (the other walls face either the attic or outside).


Quote:
Seperate concern: The wall between the theater at the adjacent room is a 2x6 shear wall with an extra 2x4 wall next to it (not touching, was added for sound-reduction, perhaps naïvely). I'm concern that I've created a "triple-leaf". Given my thoughts above, can someone let me know if this is something to worry about? Can I do anything about it? I can't remove the plywood because it's shear wall (structural requirement).
Back to your situation.... Again looking at your walls.... Even though you have double stud walls, as @kmhvball pointed out, the wall in between those studs is a no-no and will create a triple-leaf effect when you cover either side of the double wall with drywall.

How is that inner wall attached and what is it attached to?

Quite frankly, in your case I would suggest you go with clips & channel for your entire room. You have a number of noise issues that would be significantly mitigated via use of C&C: windows, concrete block, triple leaf wall, floor above ceiling.
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Im mid build with my house and Im starting to notice I have a few issues about to pop up. Ive had a busy year so far and the house and theater planning has taken a second seat to the priorities like the health of my family and other things. Everything is fine and we are back on track but I just need some help steading the ship lol.

This morning I notice the ducts for my aircon go in. I totally forgot about this.


Also Ive run a little dry on my budget. I have r2.5 insulation in the walls and ceiling with 2 layers of 10mm ordinary plaster and a double stud wall separating the hallway and bedrooms. But now I hear I should go 17mm Marine Ply wood on all the walls first then a single layer of plaster. I accept sound is going to get out but just trying not to blow the budget. Im lucky my wife let me have a room this big and not just a spare bedroom. I will have in ceiling speakers but they will have back boxes but you cant do that with pipework. I also got told to forget about mounting my in wall speakers as i was the sound proofing by cutting holes so I will make boxes forf my speakers lol. I could have just bought freestanding and bookshelfs haha. And then the lighting too. So any help would be great for this poor confused man.

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post #1619 of 3163 Old 08-25-2016, 06:02 AM
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Quote:
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What's the difference in performance between clips/channel and a floating joist ceiling? Particularly at attenuating bass? I think it'd be a lot easier to do clips on my ceiling, but would consider joists if the gains were large enough.
A floating ceiling is the gold standard, but most people don't have the option for one reason or another (most often it's the starting height of the room for example). Clips & channel are your next best bet. You also want lots of mass in between the sound source and whatever you don't want it to reach.

Regarding floating joists, you will need to take into consideration the span of your joists and how much weight they will hold. Those values dictate your options for joist height and width. I created a rather comprehensive spreadsheet in Excel indicates one's options for joist dimensions if you input the joist length. I'll see if I can work on cleaning it up this week and try to post it this weekend. It's easier than pouring over span tables.

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Originally Posted by hatlesschimp View Post
Im mid build with my house and Im starting to notice I have a few issues about to pop up. Ive had a busy year so far and the house and theater planning has taken a second seat to the priorities like the health of my family and other things. Everything is fine and we are back on track but I just need some help steading the ship lol.
Just wanted to say you are not alone. Beginning late last year, my life hit the pause button when one of my kids developed a very serious infection that resulted in a (physical) disability. So, I get that completely what you're going/been through. In my case, it was a motivator to push me to begin my HT transformation from the "media room" that it was before. I needed an outlet.


Quote:
Also Ive run a little dry on my budget. I have r2.5 insulation in the walls and ceiling with 2 layers of 10mm ordinary plaster and a double stud wall separating the hallway and bedrooms.
Is there a complete physical separation and de-coupling between those double-stud walls? I can't tell for sure but it appears in one of your photos there are wood blocks in between the stud walls. That would be a bad thing as it physically connects them, dramatically reducing their effectiveness. Unfortunately, this is a common issue with typical builder-installed double stud walls. Even if that is the case, while you can access the framing you may be able to de-couple them by removing said blocks and using clips (e.g. DC-04), but you'd have to examine the situation carefully first and also take into consideration local building codes (and perhaps take this step between building inspections).

Quote:
But now I hear I should go 17mm Marine Ply wood on all the walls first then a single layer of plaster.
No, that's not true. At least not from a sound attenuation standpoint. 2x drywall/sheetrock or plaster will work well. What would be ideal is to insert a viscoelastic compound in between whatever the 2 layers are (e.g. Green Glue). It will help noticeably with sound reduction. It's not a miracle worker, but it is similar to adding another layer of plaster (and in some frequency ranges, better).


Quote:
I also got told to forget about mounting my in wall speakers as i was the sound proofing by cutting holes so I will make boxes forf my speakers lol. I could have just bought freestanding and bookshelfs haha. And then the lighting too. So any help would be great for this poor confused man.
Yes, it's much better to avoid making holes in your sound-proofed chamber whenever possible. After all the effort to contain sound, you don't want to create easy paths that let it in/out again. Many people use columns to hide surround speakers. That's probably the most common method of concealing in-wall type of speakers while keeping them inside the sound-proofed shell. Might that be an option for you? Make sure you take into consideration your seating plans (width, location in room) and where other things will go. You shouldn't need more than 100mm of depth (maybe less) for the columns to hide your speakers - presuming they are "in-wall" speakers.

Another tip for you.... While you're at the HVAC flex duct stage, try to ensure your supply vents in the HT room will be at the "front" of the room (toward the screen), and any return vents (if present - hopefully) are toward the rear of the room and definitely behind the seats. If you don't have a return vent in the room, I would strongly suggest insisting one is added. Also make certain they calculate the room load for 6-10 air changes per hour. I realize it may be a bit late in the process for you the HVAC stuff, but it would make your life easier if it could be handled before the HVAC is finalized and the walls/ceilings are up. Anything you can get the builder to do in this regard would be a plus. The return vent will matter if you truly seal the room (including the door) in an effort to make it as air-tight as possible.
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