Preliminary Design Considerations-Basement Aspiring to Amaze

OK, I hope I haven't frustrated you guys into silence :) One good update is that we are pushing back the HVAC guys, so they're not coming next week. That buys a few weeks, but unfortunately (for the studio project but fortunately for me!) we're going on a babymoon to Europe next week and the week after. So that will be awesome, then it's pedal to the metal for the next 5 months when I get home. Any thoughts in the meantime would as always be appreciated. And I've started working on the Sketchup model in earnest, and it's coming along decently. Probably won't get one posted until I get back because I want it to be as well fleshed out as I can make it right now, with the caveat that there are some "known unknowns" still, and I'll be tweaking extensively.

Sorry about making you wait. I've been swamped!

CFM = 160, I believe. I did this by using 6 air changes an hour x 1600 cubic feet of air (200 ft2 of studio x 8 ft high) divided by 60 minutes.

:thu:

I saw in Rod's book that you need about 15 cfm per person (saw 22 on another post here) - am I understanding correctly that this would be the amount needed to dump overboard? So if I almost always have 2 people in the room, I would need to make up 30-44 CFM, or about 20-30%?

25-30% is what you should be exchanging :thu:

So how would I check this against my current system? Ask the contractor if it can handle an additional 160 CFM?

The CFM is one part of the equation (that's how much air your fan can move). However, the BTU rating of your system is what is really going to throw things for a loop.

And if we add a return (tied into the existing system?), if it can remove 30-44 CFM?

Here's another problem with trying to tie into an existing house system -- most homes are leaky, and older ones don't even have a designated stale air out system other than bathroom exhaust fans, which as you know aren't getting used very much. However, they provide yet another leaky spot in the home for the stale air to leave through. The home system typically has a fresh air intake that is FAR from 30% of the system CFM. So, if you wanted to tie into your system and have a true 30% fresh air intake, you'd have to upgrade your fresh air intake a pretty crazy amount. And if you aren't running your fresh air in and stale air out through an HRV, you'll be wasting a ton of conditioned air. An HRV that is sized for an entire home CFM at 30% will be very very expensive. Now, to rewind in my point a bit, I mentioned that older homes don't typically have a designated stale air out system. So, if yours doesn't, you'd have to implement one as your room is air tight!

OK, so if we go with 160 CFM, and say we want 200 FPM at the register, it appears to me that I would want my registers to be about .8 ft2 (160/200), which is about 115 in2. So register size would be something like 16"x8", which seems to be common enough.

:thu:

I don't know what options I have yet on duct sizes, but I think the existing ductwork is 8"x8", so about 50 in2. So I'll need to obviously do some more math but that seems to be in an ok ballpark to build the silencer boxes and double the air volume, if I'm understanding this (somewhat) correctly. I should have options on where to put them so I think I can worry about these particulars later.

You say existing ductwork -- is this existing work designated for your room area or is it going elsewhere?

OK, I'm having trouble figuring out how to calculate the static pressure. I'm seeing that you need to know the length of the duct run, but I will have some control over that. I'm thinking it would be roughly 20 total feet with one 90 degree bend, but the calculators and search results I'm finding are like reading Greek. Any advice?

This is annoying to sort out for sure. I have a pretty crazy process myself. It includes several different resources and a lot of annoying steps. The hilarious thing is that talking to several different "HVAC journeymen" they all say they never figure this out for their designs and just assume blah blah blah. So, I bought an app called ASHRAE DFDB and in it, you can type in your elbows and such to determine their loss coefficients. This is extremely helpful for determining your loss coefficients in your silencer boxes which may have 90 degree corners with no vanes, beveled throats, rounded throats or radius heel. For our sharp 90 degree corners, I use ASHRAE fitting CR3-6. This app also gives you the air velocity through the elbows (in your case based off of the 160 CFM). From there, I figure out the equivalent center distance of the length of duct or elbow. From there, I also use a Rect duct to RD duct equivalent converter. With this info, I can calculate the total friction loss, dynamic loss, and of course, adding those will give me the total static pressure. I can add up every chunk of the system. Then using the manufacturer specs, you can figure out the pressure drop across the filters and crap. Then you'll know your total in wg your fan will have to overcome. Also, I can't remember every detail about you build, but you say you will only have one 90 degree bend? Are you saying you aren't going to have any HVAC silencers? In other words you aren't going to have any isolation? IF you are wanting to build a room with isolation, you'll need a total of 4 large silencer boxes per room. Each one having at least 3 baffles in it. So, even if you come in either end of the silencers, you will have SIX 90 degree bends per silencer, so a total of 24 90 degree bends. If you come in and leave the top and bottom of each box, that adds another 2. So 4 boxes with 8 90's in them will be a total of 32 90 degree bends. Trust me, this adds a TON of static pressure to the system. Your best way to alleviate the static pressure caused by these bends is to have a massive cross sectional area. With this comes size of course. So, it's a catch 22! You have to design your system with as little static pressure as you can because as you can see, your in wg sure adds up fast!

I re-did the math, and I think a normal scenario would be closer to 7,000 btu from gear, lights, people, etc. I don't know how to calculate the load of the replacement fresh air...

Welcome to the party. This topic in particular is such a challenge because every site or person I've talked to lands me with values that are half or double the last calculation I did. I'm actually going to meet up with a company which will hopefully give me a legit answer on this. However, the most convincing method I've used is on this site (follow the steps): http://www.tombling.com/cooling/heat-lo ... ations.htm Note: their online calculator didn't work for me so I did it manually.

I also plan on running at least one or two dehumidifiers in the basement, including one in the studio, pretty much no matter what (obviously not while tracking and mixing). I don't want to factor that in necessarily, but I figure the dryer the better in general.

Not necessarily. From what I've learned, for a studio, you want to aim for around 40% relative humidity, not as dry as possible. I know a lot of people prefer like 27% or whatever, but with a properly designed system, you should be able to tweak this number to whatever you want.

So...my head is swimming even more than before, but please tell me I made some progress here :) Any help figuring out the rest would be greatly appreciated.

At least your head is swimming. My head feels like it's under water drowning every day hahaha You're doing great!

1. Tap off existing ductwork with an appropriately sized silencer box and register to get air into the room

Balancing dampers, ductwork, 4 silencer boxes. Also, upgrade your system to provide 25-30% fresh air into it's system -- this means the entire house get 25-30% fresh air which means you're dumping a lot of conditioned air overboard so you should get a expensive ass HRV. This HRV would also serve as a designated stale air out mechanism.

2. Have contractor install a return of the same size, with the same size silencer box and register, connected to the overall system (UPDATE after Greg's post - so no? I should install return and vent to the outside?)

Returns would tie into your existing system's returns and then off that return, you'd tap in an HRV system as per the diagram.

3. Run a new vent outside (not connected to the existing system) to bring in roughly the same amount of air that is being removed from the return

It would connect to the existing system as you need your supply air to have fresh air in it. The only way to condition fresh air is to have it enter your air handler unit via the return air. So, like the diagram, you'd put an HRV in the return path.

Possibly an inline fan or two in this setup? Again, if I'm missing a clear explanation of all of this, I apologize, and please feel free to chastise me (while hopefully providing links) :)

Having multiple fans work in unison is apparently as difficult as winning the lottery. It seems the best bet is to use an HRV as their supply and return fans are in sync.

UPDATE: Thanks Greg! I wrote this before I saw your post. I'm not sure if an HRV is an option or not yet.

If you're able to find a solution that works, please share it. After many discussions and research, it seems this is about the only option that will efficiently do the job :? If it inspires you, I'd like to share that I went to check out yet another commercial studio for me to cut drums in while I build my studio and like all of the others, it is built so incorrectly that their rooms don't even have return ducts in them. The owners say the supply ductwork is "sound proofed" yet you can hear things coming through the ducts from the other side of the building. Within 10 minutes of being in the control room (the acoustics of these places is a different story!), it felt stuffy and uncomfortable. Don't cheap out on your HVAC. If you want the most easy (but not cheap) solution, get a ductless mini split and an HRV. The ductwork is small (remember, only 25-30% of your CFM) and your HRV will take care of it! Greg

Sorry about making you wait. I've been swamped!

Oh man, please do not apologize! The amount of help y'all are providing is just amazing, and I feel honored to receive any replies at all :) Thanks for the clear replies to the first couple points! Next:

Here's another problem with trying to tie into an existing house system -- most homes are leaky, and older ones don't even have a designated stale air out system other than bathroom exhaust fans, which as you know aren't getting used very much. However, they provide yet another leaky spot in the home for the stale air to leave through. The home system typically has a fresh air intake that is FAR from 30% of the system CFM. So, if you wanted to tie into your system and have a true 30% fresh air intake, you'd have to upgrade your fresh air intake a pretty crazy amount. And if you aren't running your fresh air in and stale air out through an HRV, you'll be wasting a ton of conditioned air. An HRV that is sized for an entire home CFM at 30% will be very very expensive. Now, to rewind in my point a bit, I mentioned that older homes don't typically have a designated stale air out system. So, if yours doesn't, you'd have to implement one as your room is air tight!

My house is definitely old and super leaky, and I'm almost certain it doesn't have a stale air out system. So OK, sounds like you are steering me towards an HRV :) Depending on price, that might be a solution I could afford, but I'm wondering if a single room "ERV" is an option. The one below looks damn near perfect - I could install myself, and it's not crazy expensive: https://www.amazon.com/Panasonic-FV-04V ... B000XJNZ1Y It's also supposed to be very quiet, but maybe I would still need to do a silencer box on it somehow? It's rated up to 40 CFM, so that is 25% of my 160 CFM, and it's rated to work well in Atlanta since it shuts off when it freezes, which it rarely does here. Thoughts?

You say existing ductwork -- is this existing work designated for your room area or is it going elsewhere?

When I finally post my layout this will make more sense, but there is ductwork coming off the furnace/AC that goes upstairs, and our plan would be to tap off of that, so that we don't have to run much more ductwork.

This is annoying to sort out for sure...

Oh man. That app is $130, which I could justify potentially as it is relatively inexpensive given the overall cost of this build, but I'm worried I will do all this work and since I don't know what I'm doing, end up with meaningless numbers because my math is wrong. Need to think and research more on the pressure issue.

Also, I can't remember every detail about you build, but you say you will only have one 90 degree bend? Are you saying you aren't going to have any HVAC silencers? In other words you aren't going to have any isolation?

I said the 90 degree bend because that's in the existing ductwork that we intend to use, mentioned above. Definitely planning on whatever silencers I need, but didn't think to include those as 90 degree bends.

IF you are wanting to build a room with isolation, you'll need a total of 4 large silencer boxes per room.

OK, I'm a little confused here. So is it 2 large silencers each for the intake and return? One on each leaf of the wall? I guess I was thinking it could be one large silencer per vent, but I'll do whatever the correct thing to do is.

Trust me, this adds a TON of static pressure to the system. Your best way to alleviate the static pressure caused by these bends is to have a massive cross sectional area. With this comes size of course. So, it's a catch 22! You have to design your system with as little static pressure as you can because as you can see, your in wg sure adds up fast!

I may be overly optimistic, but I think I can figure out a way to get pretty large silencers without giving up too much space, by putting them in dead zones or "outside" the room, basically taking up space from a planned non-studio storage area or the foyer. Again, this will make more sense as my layout develops. But by and large, if I don't feel confident in my pressure calculations, is it a reasonable safeguard to build very large silencers with huge cross sectional areas to minimize pressure problems?

Welcome to the party. This topic in particular is such a challenge because every site or person I've talked to lands me with values that are half or double the last calculation I did. I'm actually going to meet up with a company which will hopefully give me a legit answer on this. However, the most convincing method I've used is on this site (follow the steps):

Awesome, thanks! I will give that a shot when I have some time.

Not necessarily. From what I've learned, for a studio, you want to aim for around 40% relative humidity, not as dry as possible. I know a lot of people prefer like 27% or whatever, but with a properly designed system, you should be able to tweak this number to whatever you want.

Gotcha. I guess my point here, and with some of my other comments and issues, is that I will not be in this room 90%+ of the time, and it's definitely an option to leave the doors open to the rest of the basement while I'm not there. So everything I'm doing will be to make it safe and comfortable for while I'm in there. I feel like if I'm keeping temperature and humidity at appropriate levels while I'm not in there, the equipment will be happy and any moisture/smell/etc. issues will be minimized, because it won't be an airtight space most of the time. Is that a reasonable thing to think?

At least your head is swimming. My head feels like it's under water drowning every day hahaha You're doing great!

:D Thank you! Swimming may be optimistic...but at least I have this site for a flotation device, to torture this metaphor ;)

Balancing dampers, ductwork, 4 silencer boxes. Also, upgrade your system to provide 25-30% fresh air into it's system -- this means the entire house get 25-30% fresh air which means you're dumping a lot of conditioned air overboard so you should get a expensive ass HRV. This HRV would also serve as a designated stale air out mechanism.

OK, I think that makes sense. I'm interested to hear what y'all think of the ERV thing I linked to above. Seems like if that could work, then I basically need to build silencer boxes for the air coming in from the existing HVAC system, and the ERV would take care of the return and fresh air component. I'm really hoping that's an option :) If not, I will ask the contractor about a whole house HRV. If it's under let's say $1,500 or so installed, I could probably swing that.

If it inspires you, I'd like to share that I went to check out yet another commercial studio for me to cut drums in while I build my studio and like all of the others, it is built so incorrectly that their rooms don't even have return ducts in them. The owners say the supply ductwork is "sound proofed" yet you can hear things coming through the ducts from the other side of the building. Within 10 minutes of being in the control room (the acoustics of these places is a different story!), it felt stuffy and uncomfortable. Don't cheap out on your HVAC. If you want the most easy (but not cheap) solution, get a ductless mini split and an HRV. The ductwork is small (remember, only 25-30% of your CFM) and your HRV will take care of it!

It definitely inspires me to know that lots of people trip up over this stuff too! ;) I'm hoping to avoid those very problems, and one way or another I will get there. I know the mini-split is an attractive option, but unless all else fails, I don't think it's in the cards for me. Contractor quoted about $3,500, give or take, and I think that is just out of my price range for this part of the build. Anyway, thanks as always!

I'm wondering if a single room "ERV" is an option. The one below looks damn near perfect - I could install myself, and it's not crazy expensive:

To repeat what I said in my last post, I'm pretty sure you'd have to put the unit in front of the air handler unit. I don't think you can just run it into your room as it won't be pumping conditioned air back into your space. PLUS, this will eat up a lot more room than necessary. If you tap into your system AND make more holes in your walls for the ERV, you'd need a total of 8 silencer boxes. That is just unnecessary space and headache dealing with silencer boxes.

It's also supposed to be very quiet, but maybe I would still need to do a silencer box on it somehow?

The silencer boxes aren't there attenuate the sound of the unit itself. It's there to maintain the isolation of your room.

When I finally post my layout this will make more sense, but there is ductwork coming off the furnace/AC that goes upstairs, and our plan would be to tap off of that, so that we don't have to run much more ductwork.

This won't work. That duct work is sized specifically to provide the correct amount of air to your "upstairs". You can't just tap off a branch like that. If you did want to tap off of a branch, you'd have to upsize the branch between your tap and the air handler itself to accommodate the extra air flow. So in short, you'd have to rip out what exists up until your tap, and redo it the correct size. Now, in order to determine the needed size, you'd have to first figure out exactly how they designed the system. There are several different design methods and you'd have to use the method they did.

Oh man. That app is $130

The app I got is the HVAC ASHRAE Duct Fitting Database iOS App. It sells for $15.

OK, I'm a little confused here. So is it 2 large silencers each for the intake and return? One on each leaf of the wall? I guess I was thinking it could be one large silencer per vent, but I'll do whatever the correct thing to do is.

Think of it this way: You have a sheet of drywall. It is providing you with x amount of transmission loss. You cut a hole in it. You've now lost that isolation. To "patch the hole" you need to obtain the same level of isolation you had before. Problem is, you need air to still come and go all while stopping the sound from propagating in and out of your room! THAT is where the silencer box comes into play. The silencer box will provide x amount of insertion loss, matching your old amount of transmission loss. So, to put this into practice, let's look at your room. If you build a room in a room, you have drywall (on outer leaf), insulation, then drywall (on inner leaf). That is TWO different masses of drywall you're cutting holes in. That means you need a silencer box on each one. You have both supply and return holes in your walls. So, that means you need four silencer boxes. The most ideal way to design your room is to have the silencer boxes live between your inner and outer leaves.

I may be overly optimistic, but I think I can figure out a way to get pretty large silencers without giving up too much space, by putting them in dead zones or "outside" the room, basically taking up space from a planned non-studio storage area or the foyer. Again, this will make more sense as my layout develops. But by and large, if I don't feel confident in my pressure calculations, is it a reasonable safeguard to build very large silencers with huge cross sectional areas to minimize pressure problems?

Remember, for your inner leaf silencer boxes, they either have to live between your leaves, or inside your room. These are the problematic ones. Draw out one on paper and check out how large it is. Remember, they need at least 3 baffles and it has to zig zag back and forth at twice the cross sectional area as it's inlet/outlet. If you have the quite standard 2 layers of 5/8" drywall for your leaves, the smallest you can make the structure of your silencer would be 1" thick MDF. You need at least 1" thick duct liner inside of the silencer. So, as an example: - inlet = 160 CFM - based on a 0.1 friction rate, your inlet duct size would need to be an 8" round duct - 8" round duct = 50.27 square inch cross sectional area - cross sectional area of your silencer box = twice the inlet. 50.27 sq in X 2 = 100.53 sq inch. - so as an example, the inside dimensions of your box could be a 10"x10" path. if your 10" dimension can be assigned to the value "x": The needed inside dimension width of your box = 2x+4 = 2 x 10 + 4 = 24". Then add the 1" MDF and 1" duct liner on each side of that: 1 + 1 + 24 + 1 + 1 = 28" wide - the height of the box is as simple as adding the MDF and duct liner to your 10" height. So that = 14" - the outer length of the box would be: (4x) + 11.5" = 4 x 10 + 11.5" = 51.5" The 11.5" I derived from: 2" for the MDF and duct liner, then x as above, then 2.5" for 2" duct liner plus 0.5" of MDF for the baffle, then x, then the 2.5 again for the second baffle, then x, then 2.5 again for the third baffle, then x again, then 2" for the other side MDF and duct liner. SO the dimensions of each silencer box would be: W = 28" (note, this is over 2 feet wide) H = 14" (note, this is over 1 foot wide) L = 51.5" (note, this is over 4 feet long) FOUR of those. That's a lot of space! If you want to for a nice low static pressure and air velocity, you could build them like Stuart does and Y split them. So, he basically builds 1 box long box that splits in the middle and off of this Y branch, he puts one of these big boxes (like I just mentioned above) off each side! This allows him to have half the static pressure, twice the cross sectional area, and half the air velocity. It's an awesome design, if you can fit them!

Awesome, thanks! I will give that a shot when I have some time.

I have a feeling that once you run these figures, you'll realize that your air handler is not designed to provide enough BTU. It's crazy, but as far as I've learned, HVAC dorks don't even calculate the basement in their cooling loads. And they aren't going to put in an oversized unit for several reasons, the biggest one being cost!

Gotcha. I guess my point here, and with some of my other comments and issues, is that I will not be in this room 90%+ of the time, and it's definitely an option to leave the doors open to the rest of the basement while I'm not there. So everything I'm doing will be to make it safe and comfortable for while I'm in there. I feel like if I'm keeping temperature and humidity at appropriate levels while I'm not in there, the equipment will be happy and any moisture/smell/etc. issues will be minimized, because it won't be an airtight space most of the time. Is that a reasonable thing to think?

Unless you're able to fully recirculate the air in your room (opening a door does not circulate air) 6 times per hour, then you're not following the ASHRAE guidelines for your room.

If it's under let's say $1,500 or so installed, I could probably swing that.

I'm not sure what things cost where you live, but an HRV costs that without installation here. It's easy enough to do yourself though.

I know the mini-split is an attractive option, but unless all else fails, I don't think it's in the cards for me. Contractor quoted about $3,500, give or take, and I think that is just out of my price range for this part of the build.

Like all of us, you might just have to save some pay cheques for a while and get your studying and design done. By the time your design is 100% complete, you could have that extra $3500 in your build out budget ;-) Greg

Man, just when I think I've figured something out, back to reality :D Sounds like the ERV is probably not an option...bummer.

This won't work. That duct work is sized specifically to provide the correct amount of air to your "upstairs". You can't just tap off a branch like that. If you did want to tap off of a branch, you'd have to upsize the branch between your tap and the air handler itself to accommodate the extra air flow. So in short, you'd have to rip out what exists up until your tap, and redo it the correct size. Now, in order to determine the needed size, you'd have to first figure out exactly how they designed the system. There are several different design methods and you'd have to use the method they did.

Apologies if I wasn't being clear but my understanding is that the contractor will be doing what you describe. They are redoing most of the ductwork in the basement, so I'll make sure for the run that we tap off of (assuming this is what we end up doing) that they start with a bigger duct so they can split off for the studio, and maintain the existing size for the rest of the run. I will not be doing this work - I'll be doing the silencer boxes and possibly HRV/ERV/whatever I end up with for that solution.

The app I got is the HVAC ASHRAE Duct Fitting Database iOS App. It sells for $15.

Thanks! I will check that out - I googled it and saw the $130, not sure what's going on there.

Think of it this way: You have a sheet of drywall. It is providing you with x amount of transmission loss. You cut a hole in it. You've now lost that isolation. To "patch the hole" you need to obtain the same level of isolation you had before. Problem is, you need air to still come and go all while stopping the sound from propagating in and out of your room! THAT is where the silencer box comes into play. The silencer box will provide x amount of insertion loss, matching your old amount of transmission loss. So, to put this into practice, let's look at your room. If you build a room in a room, you have drywall (on outer leaf), insulation, then drywall (on inner leaf). That is TWO different masses of drywall you're cutting holes in. That means you need a silencer box on each one. You have both supply and return holes in your walls. So, that means you need four silencer boxes. The most ideal way to design your room is to have the silencer boxes live between your inner and outer leaves.

Thank you for the clear description. That, plus the explanation of sizes and Stuart's design, is very helpful.

I have a feeling that once you run these figures, you'll realize that your air handler is not designed to provide enough BTU. It's crazy, but as far as I've learned, HVAC dorks don't even calculate the basement in their cooling loads. And they aren't going to put in an oversized unit for several reasons, the biggest one being cost!

So far he is saying it's not a problem, but I still need to run several new things by him. We shall see.

Unless you're able to fully recirculate the air in your room (opening a door does not circulate air) 6 times per hour, then you're not following the ASHRAE guidelines for your room.

I hear ya. I'm not sure how one would be able to calculate that, but fwiw there will be two doors/entrances into the studio, both into my supremely leaky basement, and certainly we're not figuring this stuff out for the rest of the basement...

I'm not sure what things cost where you live, but an HRV costs that without installation here. It's easy enough to do yourself though.

Gotcha. I'll have to ask the contractor, and it might be an option for me to do it myself. But just so I'm clear, and leaving out numerous factors, and assuming that the current system can handle it, a combination of a whole house HRV, plus supply and return vents into my studio into the existing system, with appropriate silencer boxes as you describe...that would pretty much be a high level description of the plan?

Like all of us, you might just have to save some pay cheques for a while and get your studying and design done. By the time your design is 100% complete, you could have that extra $3500 in your build out budget ;-)

Fair point :) Unfortunately my timeline and budget are not going to allow me to do this 100% how I would like, but it's gonna be the best I can do under my circumstances.

Apologies if I wasn't being clear but my understanding is that the contractor will be doing what you describe. They are redoing most of the ductwork in the basement, so I'll make sure for the run that we tap off of (assuming this is what we end up doing) that they start with a bigger duct so they can split off for the studio, and maintain the existing size for the rest of the run. I will not be doing this work - I'll be doing the silencer boxes and possibly HRV/ERV/whatever I end up with for that solution.

So what happens when you're sweating your ass off in your air tight room and the rest of the house is comfortable? There will be a thermostat in the main living area. This is what will control your air handler. Unless you zone the system (which is pretty much impossible without a variable speed fan, your room will always get neglected by the system.

So far he is saying it's not a problem, but I still need to run several new things by him. We shall see.

I wouldn't trust this guy. How on earth can he say it will be fine without you giving him numbers and him doing calculations to figure out what the rest of your house needs and then checking to see if the air handler will provide all of that? Sounds like he just wants your money and then when the job is done and things are uncomfortable, is he really going to warranty his design using existing old equipment? Nope.

I hear ya. I'm not sure how one would be able to calculate that, but fwiw there will be two doors/entrances into the studio, both into my supremely leaky basement, and certainly we're not figuring this stuff out for the rest of the basement...

Hypothetically, let's say you could recirculate air in your room via the doors (blocking the openings off with fans that would move the air of course), legally, you can't exhaust stale air into a living space. So that's off the list of possibilities.

that would pretty much be a high level description of the plan?

:thu:

Fair point :) Unfortunately my timeline and budget are not going to allow me to do this 100% how I would like, but it's gonna be the best I can do under my circumstances.

Why don't you just throw up some gobo's or basic 2'x4' panels and stuff some insulation in the joists above and use it as it is while you make a plan and save up some money to do it safely and correctly. Imagine going through all of this and having it perform horribly. So much so that you physically can't stand to be in the room due to humidity and temperature issues. Then top that off with poor isolation. You will be better off throwing together a ghetto set up. Right now, I'm working in a ghetto set up and as uncomfortable and not perfect sounding as it is, I'm still making money that I can put towards my dream studio. May I remind you that your thread says "Basement Aspiring to Amaze"? Don't get overwhelmed. I think it's pretty clear that myself and others are here to help in any way we can. You just have to be willing to take the necessary steps to do this correctly. Unless someone is holding a gun to your head, there's no reason you can't makeshift a space together to work out of while you finish your design and save some money up. Greg

So what happens when you're sweating your ass off in your air tight room and the rest of the house is comfortable? There will be a thermostat in the main living area. This is what will control your air handler. Unless you zone the system (which is pretty much impossible without a variable speed fan, your room will always get neglected by the system.

That's obviously a major concern. As it is right now, when we run the AC, it runs pretty consistently to cool the rest of the home. My lady knows that it's possible that we would have to keep the upstairs cooler if this becomes an issue, and she's ok with that. I guess I just find it hard to believe that this isn't possible - I've seen other threads on this forum where people, even in basements in the south, tapped off their existing systems and have great studios. Here's one that I have bookmarked and is somewhat similar to my situation: viewtopic.php?f=2&t=18680

I wouldn't trust this guy. How on earth can he say it will be fine without you giving him numbers and him doing calculations to figure out what the rest of your house needs and then checking to see if the air handler will provide all of that? Sounds like he just wants your money and then when the job is done and things are uncomfortable, is he really going to warranty his design using existing old equipment? Nope.

I have not done a good job describing our interactions, or that he's done great work for me before. True, he readily admits he does not have experience with studios, but he's trying to understand and do what I'm asking, and he's a very standup guy with a reputable company. The issue is me conveying information to him, not him giving me unrealistic assurances or promising everything will be ok.

Hypothetically, let's say you could recirculate air in your room via the doors (blocking the openings off with fans that would move the air of course), legally, you can't exhaust stale air into a living space. So that's off the list of possibilities.

I think this also might be an issue of miscommunication, and will be greatly helped once I have the layout in better shape. I'm of course only saying I'll leave the doors open when I'm not using the room, and the rest of the basement will be conditioned as well. I guess I would think all of the air would be shared - I wouldn't be exhausting into somewhere else, it would just be an open area.

Quote: that would pretty much be a high level description of the plan? :thu:

I feel like this is real progress :)

Why don't you just throw up some gobo's or basic 2'x4' panels and stuff some insulation in the joists above and use it as it is while you make a plan and save up some money to do it safely and correctly. Imagine going through all of this and having it perform horribly. So much so that you physically can't stand to be in the room due to humidity and temperature issues. Then top that off with poor isolation. You will be better off throwing together a ghetto set up. Right now, I'm working in a ghetto set up and as uncomfortable and not perfect sounding as it is, I'm still making money that I can put towards my dream studio.

This is a very fair point, but at this point I'm trying to avoid it. It may be inevitable, but for a variety of reasons, I'm going to push forward, at least for now :)

May I remind you that your thread says "Basement Aspiring to Amaze"? Don't get overwhelmed. I think it's pretty clear that myself and others are here to help in any way we can. You just have to be willing to take the necessary steps to do this correctly. Unless someone is holding a gun to your head, there's no reason you can't makeshift a space together to work out of while you finish your design and save some money up.

Touche! In the end, you may be right. I'm not trying to half ass this, and many of the issues here are that I just don't understand the HVAC stuff in particular. On the other hand, I don't want to make perfect the enemy of the good, or whatever that saying is. My worry is that if I don't finish this in the window that I have open right now, it will be years before I have another chance, especially with a baby on the way.

What a great thread guys. Its really making me think about my studio build. The mini split system with the HRV might be the thing I need. Now to do more research on the HRV install.

OK, I'm back! And ready for more abuse...I mean reality checks ;)

What a great thread guys. Its really making me think about my studio build. The mini split system with the HRV might be the thing I need. Now to do more research on the HRV install.

Glad to hear it, and you'll probably have a better set up than I do :) Anyway...got some more information. The HVAC guys are coming either Thursday or Friday so I need to get this as sorted out as I can. It's sink or swim time for me :) So I've pretty much ruled out the whole house HRV unfortunately. We just don't have the budget for it. And it's not a matter of saving up more money - we have other financial needs coming up (see: baby, plus a new car for the lady, etc.). So, I need to do the best I can with what I have. I spoke with the HVAC contractor, we are able to put a return into the room, on the existing system. Also, he's hoping to be able to run a new duct line into the room, so it won't be "tapped" off an existing line like I originally thought/described. So if I'm understanding this correctly, that will basically take care of the heating and cooling requirements, but now my issue is once again ventilation. Is the only issue with the single room ERV that I posted earlier (such as this: https://www.amazon.com/Panasonic-FV-04V ... B000XJNZ1Y) that I would have to build additional silencer boxes? I agree that that sounds like no fun, but it also seems like a DIY and cost effective way to solve my problems. I feel like I could mount it in the room, and it has two 4" ducts that would have to go outside, which seems achievable. Reading more, it also appears to be compatible with a Y connector to a single 5.5" duct, so in theory it would only be two additional (and not ridiculously huge) silencer boxes. Does anyone have experience with such a thing? Are there any other options that I should be exploring? I apologize if I'm being frustrating (I'm pretty frustrated myself!) - I would love to have more time and money and do this, but I just don't. Of course, I'd also love for it not to be in this terrible basement, but here we are :)

Hello! OK, HVAC dudes are coming tomorrow, so any last minute advice or warnings (especially about the single room ERV thing) would be greatly appreciated! I figure no matter what, I'm having them put in the supply and return (location still to be determined) and I can always have them come back if I absolutely need to change something. Part of the reason for the rush is because they are moving around all the crappy ductwork, which needs to happen before we can continue framing other rooms, and especially my father in-law's room. In other news, I have a first draft of a SketchUp model, after many hours of work! I'm getting the hang of the program, and mostly using groups instead of components, so I hope that's ok. I'm including two PNG files, but it's saying the actual SketchUp file is too big to upload. I can put it on DropBox if that would be helpful. Anyway, I know it's a super crazy shape, but this is what I had to do to carve out as much space as possible for myself. The little cubby area in the top left of the second pic is to be used as a painting studio, because of course I can't just make music in here :) I'm thinking that my desk/computer/speakers will go on the wall near the top of the second pic (with the green insulation), and I'm trying to figure out the soffits, if angled walls are doable, etc. I also know I need to add some walls and obviously haven't done a lot of other work, but I thought the layout was at least done enough to get initial impressions. Rough measurements are that the longest open part is about 14' 6" from where I want to put the desk to the wall behind, and about 11' 9" across from the door to the wall in front of the furnace. I'm working on another post soon with more detailed questions and will continue to work on the SketchUp design, but I wanted to put this out to follow up on the HVAC situation and get any initial thoughts on the layout. Thanks a million as always!! -Dan

Hey Dan! Good work with SketchUp so far! I personally don't use Groups much, but there are certainly times they come in handy. 99% of the time I use and prefer components. If you want to copy something but don't want it attached to the other components, just copy it, right click it and make it unique. Sorry I didn't reply when you were asking. I haven't had internet for almost 3 weeks. Finally got it hooked up today! I understand that you're trying to make the best out of the space you have. Having said that, remember that you need a symmetrical listening position (at least for the front half of your room. So if you need to build walls or move doors to make that happen, do it. I don't fully understand where you're picturing the mix position. Maybe draw in some speakers and some furniture (including your father in laws bed) to show what rooms are being used for what. How did the HVAC stuff go? You're correct in saying that you will need the extra silencer boxes. The financial part isn't the issue, rather the space to fix the boxes. I know you think they are small, but they aren't :-S Greg

Greg! No worries, on the delay, and thanks for the response!! Basically groups were the first thing that worked for me so I went with that, but I have much room to improve :) Glad you're back online, I'm jealous of the time unplugged ;)

I understand that you're trying to make the best out of the space you have. Having said that, remember that you need a symmetrical listening position (at least for the front half of your room. So if you need to build walls or move doors to make that happen, do it. I don't fully understand where you're picturing the mix position. Maybe draw in some speakers and some furniture (including your father in laws bed) to show what rooms are being used for what.

I'm starting to feel more optimistic, but that could change at any point. I've attached a new pic below with a very general idea of where I'm thinking the mix position will be. I still need to figure out angles, wall lengths, etc., but the circle is where my head would be, theoretically - about 38% the length of the room. Then I did 45 degree angles off of that, and tried to make it work. My thought is I could make the angled wall that doesn't hold the speaker, at least on the furnace side, so that it could move out of the way when I need to go back to the painting area. But this is all still very much up in the air. Also I'm still working out how/where I would add other room treatments, and I don't want to screw myself too badly if I can avoid it.

How did the HVAC stuff go? You're correct in saying that you will need the extra silencer boxes. The financial part isn't the issue, rather the space to fix the boxes. I know you think they are small, but they aren't :-S

It went! I think it's ok, and believe me, you've already successfully disabused me of the notion that the silencer boxes are small ;) I did want to run some thoughts by y'all on the main supply and return boxes. So the HVAC guys, at my request, basically ran the lines to either side of the furnace, and left them hanging there for me to mount when I figure out the silencer boxes. Hopefully you can kind of see that in the other attached pics. So basically my question is, do I need to build two walls to enclose the furnace, or can I consider the outside wall/foundation to be the first leaf of the system? Obviously the latter approach is the more attractive, but I don't want to screw my isolation. I'm less concerned about sound getting out the side of the house than I am about it traveling upstairs. So I could do my best to beef up the area above the furnace, but there will be parts that I can't reach. My thought was that it might work for the whole furnace area to be considered the "void" between my two leaf system, so then I would just need to build the inner wall for the studio and would only need once silencer box. Does that make sense? And as you can hopefully see from the pics, I've tried to leave a good amount of room for the silencer boxes, in areas that are sort of out of the way. I think I'd still be ok if I need to build the second wall to seal off the furnace, but obviously that will be more lost space and more work, so it would be awesome to not have to do that :) And also, I do know that I need to provide access to the furnace - still working on that but basic plan right now is to have removable modules in the wall - basically same material that fits super snugly in an opening, but has grab bars so they can be lifted out of place for the furnace to be serviced.

I've attached a new pic below with a very general idea of where I'm thinking the mix position will be. I still need to figure out angles, wall lengths, etc., but the circle is where my head would be, theoretically - about 38% the length of the room.

You may find that your soffits won't be deep enough with the framing and speaker enclosure/ventilation to hold your speaker. That may result in you bringing that entire front soffit wall assembly towards you. Note though, your mix position is based off of your inner leaf dimensions, so your position should stay the same. Your soffit angles may just change. And, that leads to my next point.

Then I did 45 degree angles off of that, and tried to make it work.

Check out some soffit design detail notes on some forum threads. You'll see things like this (this is via soundman2020): 1) The speakers should not go in the corner, nor on the line that divides the corner. In other words, if your walls intersect at 90°, then draw a line out from each corner at 45°, and stay away from that: don't put your speaker exactly on that line, since it implies that you'll be getting the same artifacts from the side walls as from the front wall. Put your speakers either outside or inside of those lines. More commonly you'll want your speakers "inside" those lines (more towards the center line of the room). 2) The "38% of room depth rule" is not a rule, but it is a useful guideline for a starting point. You'll generally want to have your listening position a bit closer to the front wall than that location, but do be aware that you might be getting into problematic SBIR territory there. (You can treat that, to a certain extent). 3) Keep the mix position away from 25% and 50% of room depth, and try to stay between about 32% and 44% 4) You can angle your speakers differently than the "textbook" 30° angle: Anything in the range 25° to about 35° will work well under most circumstances. 5) Keep the speakers as far apart as possible, wile not violating rules 1 and 4. 6) Keep the mix position at a good distance from the speakers, within the range of about 1m to about 5m. Further away is usually better. 7) Don't put the speakers at 25% of the room width: that's a modal null for some frequencies, and a peak for others. Try something more like 28% to 34%. 8 ) Make the front baffle of your soffit as wide and tall as you can, within reason. The width should be at least three times the diameter of your low frequency driver. In other words, if you have a speaker with an 8" woofer, then you want the soffit baffle to be at least 24" (60cm) wide. Wider is better. 9) Do not put your speaker in the middle of the soffit baffle: Offset in both directions. In other words, the distances from the acoustic center of the speaker to each edge of the baffle should be very different, by at least 20%. So for example if your speaker axis is 30cm from one side of the baffle, it should be more than 36cm from the other side, less than 24cm from the bottom edge, and more than 44cm from the top edge. (Rough distances, for illustration only...). Larger differences are generally better. 10) Make the baffle as massively heavy as you can, and as rigid as you can. 11) Make the structure inside the soffit (the framing that holds the baffle and speaker in place) as rigid and massive as you can. 12) Mount the speaker inside an enclosure box that is either a very tight fit, in order to keep the speaker rigidly fixed in place, or mount it on suitable rubber pads, to completely decouple it from the the box. Carefully choose the properties and dimensions of that rubber, to make sure the speaker is still decoupled down to at least one octave below the speaker's low cut-off frequency. 13) Take into account that speakers need a lot of space behind them for cooling, and a path through the soffit for cooling air to flow. 14) Rear-ported speakers need special attention: Do not overload the rear port, acoustically, with an enclosure box that is too small, or un-ventilated, or un-damped. 15) Damp the hell out of the soffit interior! Fill it entirely with suitable damping if you want, except for the cooling path. Also, angle your soffit baffles so that the speakers fire across the tips of your ears, not your eye balls like you currently have drawn in your SketchUp!

My thought is I could make the angled wall that doesn't hold the speaker, at least on the furnace side, so that it could move out of the way when I need to go back to the painting area. But this is all still very much up in the air.

How would you maintain your isolation with this movable soffit? This would be a crazy design. I'd try to avoid that if possible. Maybe you could make your soffit wing out of a flat door?

Does that make sense?

I'm tired, so maybe that's my problem, but I don't quite follow your explanation. Maybe a crappy drawing in SketchUp would clarify it for us?

And also, I do know that I need to provide access to the furnace - still working on that but basic plan right now is to have removable modules in the wall - basically same material that fits super snugly in an opening, but has grab bars so they can be lifted out of place for the furnace to be serviced.

Don't make things large enough to just service the furnace -- make it big enough to REPLACE the furnace. Greg

Thanks a ton for the detailed info on the room layout! I will be spending a bunch of time figuring that out in the next couple of weeks, and will definitely be sure to keep all of this in mind. Any thoughts on my question about whether I need to build a second wall in front of the furnace, or if I can consider the outside wall/foundation of the house as the outer leaf? For the other stuff:

You may find that your soffits won't be deep enough with the framing and speaker enclosure/ventilation to hold your speaker. That may result in you bringing that entire front soffit wall assembly towards you. Note though, your mix position is based off of your inner leaf dimensions, so your position should stay the same. Your soffit angles may just change. And, that leads to my next point.

Awesome, I will definitely work this into my plans. The rest of the info is super helpful, and like I said, I'll incorporate it all into my eventual design. I think I have an ok space to work with at this point.

How would you maintain your isolation with this movable soffit? This would be a crazy design. I'd try to avoid that if possible. Maybe you could make your soffit wing out of a flat door?

I'm not doing a good job of explaining this, and it will hopefully make more sense with a better drawing, but basically the left side of the listening position will not really be doing a ton of the isolation work, because it's all isolated behind and to the side of it. So this will be interior to the room, and my understanding is that it will mainly be for creating the RFZ listening area, not for isolation. And note that it's only the "second" angled wall, in order to have an easier pass through to the painting area off the back. The speaker enclosure will be permanently installed. But if this isn't workable I can figure something else out, just seemed like a possibly good solution.

Don't make things large enough to just service the furnace -- make it big enough to REPLACE the furnace.

Good call - fortunately it's less than a year old, but it should be doable to provide space for replacing it, hopefully in like 20 years :)

Any thoughts on my question about whether I need to build a second wall in front of the furnace, or if I can consider the outside wall/foundation of the house as the outer leaf?

As long as your recording space has an inner leaf and outer leaf, you're good to go. Draw those leaves up and you'll find any flaws in your plan quickly.

I'm not doing a good job of explaining this, and it will hopefully make more sense with a better drawing, but basically the left side of the listening position will not really be doing a ton of the isolation work, because it's all isolated behind and to the side of it.

See my first point.

So this will be interior to the room, and my understanding is that it will mainly be for creating the RFZ listening area, not for isolation. And note that it's only the "second" angled wall, in order to have an easier pass through to the painting area off the back. The speaker enclosure will be permanently installed. But if this isn't workable I can figure something else out, just seemed like a possibly good solution.

This isn't your "interior room". You can call these your treatment walls, or false walls. They aren't sealed or anything. Heck, they might not even have drywall on them. They're just there for acoustic treatment, not isolation. I look forward to your progress! Hopefully these answer help! Greg

Awesome, thanks as always! Back from Thanksgiving break, hoping to get lots of planning and start of some of the basic construction stuff between now and Christmas. Whew! So I'm still trying to figure out this deal with the furnace. I found another thread that had a pretty similar issue - link and quote are below. Based on that, it seems like my best bet is to build the outer leaf wall in front of the furnace, and to basically not consider the outer wall of the house to be the outer leaf on that side of the room. Does that make sense? Or would I still be ok just building the inner leaf wall and consider the outer wall of the house to be the other leaf? In the second scenario, the whole furnace and ductwork would be in the "void" between my two leafs. In the first scenario, all of that would be behind both leaves. And does it make a difference that all of my ductwork is insulated, rather than just metal? Also, I was wondering about fastening the base plates for the wall to the floor. I read that you should run three beads of acoustical caulk on the lumber prior to fastening to the concrete floor. Is that all I need to do? They don't need to be decoupled in any other way? That's going to be the only part of the studio that touches the rest of the house, and my understanding is that that's fine, but I wanted to make sure. Link to thread mentioned above: viewtopic.php?f=2&t=18680&start=30 Quote:

Quote: I was originally thinking I would build a soffit around it with double 5/8s and have it occupy the space between the foundation wall and inner leaf for isolation purposes but then realized it would still be open on top so I think this might be pointless, Your basic plan is correct, but you also need to fix that "open on top" part, by enclosing it 100%. Quote: now I'm thinking that I will just leave it on the outside of the inner leaf and port it into the studio through a vent muffler which I was going to do anyway. If you did that, it would be in between your two leaves, and become part of your air gap. You do not want to do that! The air gap is where all the serious resonance business happens, inside an MSM wall, and since your HVAC duct is basically just a resonant box itself, made with thin metal walls, it will gladly pick that up and send it all over your house! Not to mention that any noise that is already present in your HVAC system will now totally bypass your outer leaf, and be present in the air gap.... So you definitely do need to soffit up fully, to make it part of the outer leaf, not leaving it inside the air.

Thanks as always for any and all help!

Also, I was wondering about fastening the base plates for the wall to the floor. I read that you should run three beads of acoustical caulk on the lumber prior to fastening to the concrete floor. Is that all I need to do? They don't need to be decoupled in any other way? That's going to be the only part of the studio that touches the rest of the house, and my understanding is that that's fine, but I wanted to make sure

:thu: - Stuart -

Sweet, thanks! For once that's what I was hoping to hear ;) Any thoughts on the other questions?

Hey y'all! Just wanted to provide a quick update because I'm still working on this! To the surprise of nobody, including myself, I am way behind schedule. More of the work of renovating the rest of the basement has fallen to me than I had hoped, and then we had some pretty bad flooding while it rained super hard for several weeks, so I've had to spend a bunch of time dealing with that. Trying to keep my spirits up, but I haven't done anything at all on the interior to my studio, and have instead had to focus on the other rooms in the basement. Bummer. Oh well, clearly this will not even be close to done by the time the baby arrives, but I'm going to keep at it...and I will end up in the finished studio thread come hell or high water! Happy New Year to all...and if you're bored and want to chime in on my questions about boxing in the ductwork, I'm still planning to get to that ;)

Sorry to hear about your bad luck! Keep chugging away at it and you'll be done before you know it! I too am feeling so behind on my build. But, I keep telling myself that every 10 minutes of work I do, I'm that much closer to being done.

So I'm still trying to figure out this deal with the furnace. I found another thread that had a pretty similar issue - link and quote are below. Based on that, it seems like my best bet is to build the outer leaf wall in front of the furnace, and to basically not consider the outer wall of the house to be the outer leaf on that side of the room. Does that make sense?

Yes, it makes sense to put your outer leaf in front of your furnace.

And does it make a difference that all of my ductwork is insulated, rather than just metal?

Depending on where it is, you really should have it insulated. Outside of your outer leaf it doesn't matter as much but in that location, it can help with actual furnace/HVAC noise. Inside of your outer leaf, everything should be insulated. Greg

Thanks Greg, greatly appreciate the support! It's been a slog already and I have tons left to do, but I'm gonna keep just plugging away. Hope you can make some good progress on your build too!

Yes, it makes sense to put your outer leaf in front of your furnace.

Awesome, thanks! That's what I figured but it's very helpful to have confirmation.

Depending on where it is, you really should have it insulated. Outside of your outer leaf it doesn't matter as much but in that location, it can help with actual furnace/HVAC noise. Inside of your outer leaf, everything should be insulated.

All of the ductwork in the basement is insulated. I'm gonna keep as much of it as possible outside the outer leaf, but on a couple places I think that's just not gonna be possible, so I'm hoping by boxing it it/beefing it up, putting Rockwool in there, and the fact that it's already insulated will not hurt my isolation too much. Thanks as always! Realistically at this point I am focusing on getting the other rooms done and that's gonna take probably til the baby gets here, but hopefully I can start chipping away at the studio room, and in the meantime I still need to finalize the studio layout, so I'll post again before too too long with updates.

All of the ductwork in the basement is insulated.

External insulation over top of the ducts themselves, or are they LINED with duct liner? What you want is for your ducts to be LINED with duct liner. This is what will improve your insertion loss. Ducts that have external insulation are improved only thermally, not acoustically. Greg

I'm not exactly sure, but you can see in the pics - I've attached another one for ease of reference. All ductwork is wrapped in the same shiny insulation.

That looks like flex duct to me. Which is externally insulated. Be sure to use internally insulated duct for all of your studio ducts! Greg

Whelp, too late for that :( I'm going to put as much as possible behind the outer leaf, and anything that is between leaves will have additional insulation...that's about the best I can do.