Turning an outdoor storage closet into a rehearsal space

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First of all, THANKS in advance for considering my situation and my questions!

I live in a townhouse. There's an uninsulated, unfinished storage closet that opens out to my deck but not to the interior of my home. I'm planning to turn it into a music "pad." It won't necessarily be a recording studio, although I'd like to lay down some demo tracks now and again, but it will be wholly dedicated to my musical endeavors: guitars, pianos, synths, singing. It doesn't need to be soundproofed in the sense that a recording studio is soundproofed. I'm ok with people being able to hear me as they walk by, but I would like it to be quiet enough that I don't annoy my neighbors at night. The space is not on the party wall side of my townhouse, but there are other condos very close to me – about 40 feet away from this space across a little grassy patch.

My budget: I'd like to spend less than $7k, but I'm flexible.

The space is very small. It's kind of like having a little garage, but it's way too small for a car. There are no windows. Floor space is just 7' x 7.5' plus a little 2' x 2.5' section in one corner. It's basically a square-ish space with a little extra space included in the corner – a space that would suit a water heater except that my water heater is located elsewhere. Ceiling height varies from 7' at one end to 12.5' at the other end (slanted). There's enough space for maybe two guitar players to jam. It'll just be me most of the time, though.

Currently, there is drywall, but no insulation. It's really beat up drywall, though. There's only one outlet and a ceiling light. The space is elevated off the ground (about 3 feet, so deck level) and not situated over a crawlspace or basement. It's actually totally open underneath... kind of like an extension of the deck, only enclosed.

My questions:

1. I know I need electrical, drywall/insulation, and HVAC. I think that's the proper order of operations, but it would be nice to have confirmation.

2. How many outlets will I likely need? I figure 2 new ones in addition to the existing one. That should be enough for three guitar amps, a keyboard amp, and a computer. Maybe a mini-fridge, too (I know, I know... those make noise). I'll be using power strips. Any thoughts on this?

3. Given my goals for sound (not soundproofed, but sufficiently sound "tight" to not annoy people), should I be thinking about anything other than standard (R-19 or whatever) fiberglass batts and standard drywall? Decoupling from the studs would be swell except I have minimal space to sacrifice!

4. Floor insulation: I was thinking about getting a spray foam kit and just foaming underneath the storage closet. It's basically just a space built over decking, and the boards holding it up are very clean and dry. Is this sensible, or should I be doing something different? Maybe some sort of insulated pad beneath some... carpeting? Speaking of...

5. Floors... Any carpet/pad recommendations?

6. For HVAC, I'm thinking a mini-split for noise, reliability, and variable speed capacity in such a small space. My HVAC guy agrees, although I suppose he has a vested interest. He thinks a 9,000 BTU unit is the way to go since I'll have a lot of equipment in there generating heat. Given the size of this space, that still seems... enormous. Any thoughts? My understanding is that oversizing a mini-split isn't that big a deal since they'll run at a low speed and low output most of the time anyway.

7. Ventilation: This is a very small, windowless room. It's going to be sealed up pretty tight. Should I be concerned about air quality?

8. What am I forgetting to ask about?

Thanks so much for considering my questions!

[Gregwor]

Welcome!

1. I know I need electrical, drywall/insulation, and HVAC. I think that's the proper order of operations, but it would be nice to have confirmation.

Well, it kind of has to get done in the order that makes the most sense for your build. You need to draw this all up in SketchUp Make (don't waste your time using the online "free" version). Make is free but it's discontinued so just download the newest one that works for your computer.

https://help.sketchup.com/en/downloading-older-versions

2. How many outlets will I likely need? I figure 2 new ones in addition to the existing one. That should be enough for three guitar amps, a keyboard amp, and a computer. Maybe a mini-fridge, too (I know, I know... those make noise). I'll be using power strips. Any thoughts on this?

In full fledged studio builds it's recommended to use isolated grounds. For your jamming situation that might be overkill. In a room that small it doesn't cost much to add a few extra outlets. Having said that, I would imagine where everything will go, put outlets in appropriate places and then add a few extra just in case. Remember, it's annoying having cables run across the floor so just place your outlets to avoid messy cabling everywhere.

3. Given my goals for sound (not soundproofed, but sufficiently sound "tight" to not annoy people), should I be thinking about anything other than standard (R-19 or whatever) fiberglass batts and standard drywall? Decoupling from the studs would be swell except I have minimal space to sacrifice!

To sound "tight", you should build your place inside out. This means that you don't end up with drywall as your finish. If I were you I would "beef up" the exterior sheathing and stuff the stud bays with insulation. Pretty simple. You can then run your electrical like normal, put fabric and maybe wooden slats on the fabric. This will mean all of your outlets and light switches will be flush to the wall for a nice clean look too.

4. Floor insulation: I was thinking about getting a spray foam kit and just foaming underneath the storage closet. It's basically just a space built over decking, and the boards holding it up are very clean and dry. Is this sensible, or should I be doing something different? Maybe some sort of insulated pad beneath some... carpeting? Speaking of...

Spray foam from the underside would be great for thermal reasons. Carpet is cozy but dirty and is not good for acoustics. I could recommend some of that play mat puzzle piece foam for your floor if you're worried about cold feet.

5. Floors... Any carpet/pad recommendations?

See my answer to question 4.

6. For HVAC, I'm thinking a mini-split for noise, reliability, and variable speed capacity in such a small space. My HVAC guy agrees, although I suppose he has a vested interest. He thinks a 9,000 BTU unit is the way to go since I'll have a lot of equipment in there generating heat. Given the size of this space, that still seems... enormous. Any thoughts? My understanding is that oversizing a mini-split isn't that big a deal since they'll run at a low speed and low output most of the time anyway.

Oversizing is bad, especially for air conditioning. Are you REALLY going to have a ton of gear running all the time? I'm guessing a computer, a few lights and maybe a few smallish guitar amps. That isn't a lot. Properly size your mini split. Using a mini split means you can have a smaller ventilation design so that's good.

7. Ventilation: This is a very small, windowless room. It's going to be sealed up pretty tight. Should I be concerned about air quality?

Yes. Put a homemade silencer box on both ends of your closet. Put an exterior fan on the end of one of them. Simple. Ideally you want your fresh air coming in above your mini split condenser so that it blows nice fresh air around. Luckily you don't need massive silencer boxes since your room isn't large and you're only going to need to ventilate 25-30% of your total CFM.

8. What am I forgetting to ask about?

Transmission loss. If you don't want to piss off your neighbours, you should figure out how much transmission loss you actually need in order to prevent the police from knocking on your door. Maybe the amount of isolation you have right now is fine and you can just yank off the drywall and stuff the walls/ceiling with insulation. OR maybe you need to add 1.5" of OSB to the outside (or inside) of your exterior sheathing. Maybe you need something more extreme than that! Nothing would be worse than building the space and then having the police tell you to shut it down.

Permits. Make all of your drawings -- I can't stress this enough. Once you start drawing it up in SketchUp, you will hit roadblocks that force you to research and solve issues. It will make you work out every last detail before you start and that is key for a successful easy build. With these drawings you can apply for permits and make sure everything is legal and your ass is covered. Imagine causing some crazy mold issue or fire and since you built it illegally you're personally on the line for everything!

Doors. Doors are a major source of sound leaking in/out of your space. There are many examples on the forum of how to properly build and implement doors.

Do you have space for the mini split heat pump? How are you getting the power to the heat pump?

Greg

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Thank you! This is incredibly helpful. I think I understand everything with one giant exception:

Put a homemade silencer box on both ends of your closet. Put an exterior fan on the end of one of them. Simple. Ideally you want your fresh air coming in above your mini split condenser so that it blows nice fresh air around. Luckily you don't need massive silencer boxes since your room isn't large and you're only going to need to ventilate 25-30% of your total CFM.

Would I be mounting a fan to the wall so that I could move air from the outdoors directly into the space? If so, this seems like a problematic ventilation system, but maybe I'm misunderstanding. In my climate, you definitely DO NOT want to push a bunch of unfiltered outdoor air inside except on a handful of days each year. There's too much pollen and humidity. The only mechanical ventilation systems people ever use are ERVs or some kind of positive pressure system ducted into a whole-house dehumidifier.

So if I was actually going to do this, I'd need to know about filtration, fan sizing, frequency of operation, and whether it would be a variable speed fan.

Also, is a silencer box just some kind of baffled box I would put around the fan? If so, why do I need one at both ends of the space if said fan is only at one end? Where might I find instructions on building this? I searched the forum, and there are several places where such contraptions are discussed, but it seems to be taken for granted that everyone understands what they are. I have really never heard of this.

[Gregwor]

Would I be mounting a fan to the wall so that I could move air from the outdoors directly into the space?

If you're able to, you should mount one silencer on the exterior of each side of your room. Instead of an exterior inline fan you could use an ERV to do the job but I'm not sure how you'll do that outside!

Also, is a silencer box just some kind of baffled box I would put around the fan? If so, why do I need one at both ends of the space if said fan is only at one end? Where might I find instructions on building this? I searched the forum, and there are several places where such contraptions are discussed, but it seems to be taken for granted that everyone understands what they are. I have really never heard of this.

You can see some on this thread: (I designed these ones and helped cut and glue/nail them)
http://www.johnlsayers.com/phpBB2/viewt ... 10&t=21704

You can also use this cool design which Y splits the air path. If you have the space you can build them twice as big as a single path version which ends up giving you twice the internal cross sectional area which gives you better insertion loss and half the air velocity. All good things. But again, twice the material and size. A Y split design would also work good when built the same size as a single path version. The benefit to this would be having your inlets/outlets in your room spaced out for a more even coverage of fresh air.

20160328_141126.jpg

Here is a quick guide I drew up to speed up the single path design:

Gregwor's Silencer Box.png

Greg