New Music Room 'Shed' floor/slab alternatives

[boomchaka]

Howdy,

I am planning/designing a 10x14 office/music outbuilding to be constructed on a rental property. The property owners
are very good friends of mine as well as supportive and encouraging of my creative pursuits and are fully aware of
the project and its scope. That being said the design and build of the structure is being approached as 'temporary'.
They hope I stay as long as possible being as I am also their 'contractor' and continue to make paid and unpaid
upgrades to the property. I have plans to buy my own property however I have no idea when. Its a money, location
and life timing thing. Our baseline agreement is when the time comes for me to leave if they need the structure gone
I am committed to tearing it down. For them and for me. I would like to be able to recycle the structure and its materials
as much as is 'feasible'. this feasibility is a pretty broad category for me. possibly all the way down to demo'ing a concrete
slab Possibly, tho I think I would rather not. which brings me to you all.

May I just say thank you now for being so committed to helping the community at large with your breadth and depth of
knowledge on the matter of creating incredible spaces to do so many kinds of sound related endeavors. it is a very noble
contribution indeed.

I've been pouring over this forum and the internet in general pretty intensely for the last week trying to figure out how to
proceed with the foundation/floor. lots of rabbit holes and tail chasing. my head is spinning with information (mostly I'm cracking my head wondering if there is a non-slab solution that acts more like a slab than a post and pier build). It seems a 2 leaf system/room inside a room on a single slab foundation( vs. pier and beam) is the optimal baseline sound control system? I get that there is so much more. But in terms of a general grok/talking point, am I understanding?

I would love to pour a slab but I am less fond of the idea of potentially demo'ing it. But being as I am starting with a blank slate I feel compelled to want to do something possibly more effective than that which is beautifully detailed out for the foundation/floor in the 'from shed to studio' design. I'm sorry but I don't have the tool(or the structure for that matter ) to test my levels in order to present a desired db reduction. I hope this lack of information doesn't end the dialogue. But how about I try and get there with...

what I want:

I play drums(by trade in a past life) but I also like to create sonic landscapes that hover in/emphasize the lower end of the frequency range. I picked up the bass once upon a time enough to learn some basics and probably would enjoy doing some more of that. fwiw, I also dabble(in so much as one can dabble) with the trumpet. if I had a place to practice where I felt like I wasn't torturing anyone with my squaks and sqeaks, I might actually dig into a regular practice routine. I don't need an overly critical listening environment but would address the interior acoustics as best I could to the degree that I appreciate the value of having a nice sonic experience. The closest neighboring structure is approximately 15' from the proposed location of the new structure. I don't need to blast whatever I want whenever I want. I just want to get a leash on what is escaping, for the neighbors sake, and again primarily in the lower end. depending on whatever sound reduction I actually ended up with I would then adjust volumes and time schedules of making noise accordingly. In other words I'll adapt to whatever the resultant sound levels may be but would like to get as much reduction as possible within my constraints....

what I have:

budget wise, pretty limited. I would say approx $1000 for foundation/floor. I already have the outer shell materials. from what I've seen online of studio builds it looks to be a fairly novel material solution so I will call it out here...

office_panel.gif

its a sandwich panel of 4" of closed cell foam with a steel panel on either side. they t&g together to form a self supporting wall system secured to the floor in a metal u channel. the roof is a similar material except 3" thick. I will be laying the roof panels on
2x6 joists 24" o.c.. from what I've read closed cell foam isn't great at sound control but I hope the inner leaf(standard build as called out on this forum, studs/insulation/2 sheets of drywall) will give me something. I procured these panels from a 3rd party private sell. they were leftover from a larger job. enough roof and walls to build this structure and then some for $800. if the sound control is a bust, at least I'll have a nice warm office on a budget

here is a beginning stages sketchup model. very much a work in progress but will hopefully give you a general idea as well as call
out some basic measurements...

office.jpg

This is going to be an iterative project driven by replenishing funds. I would build the foundation/floor and outer leaf. probably use the space as an office and limited use music room to start with. eventually coming back around to building the inner leaf. my hope is to start off on a good footing, pun intended.

soooooo, my questions are:

is there a non-slab that acts like a slab solution? in other words a slab that is easily demoable, like say oh I dunno, a field of cinderblocks fill with sand? or thick pavers bedded as if it were going to be a slab then a thin ish layer of sand/cement screed on top to tie it all together. I'm throwing spaghetti on the wall here and realize there are structural considerations. I have some other squirrly ideas but perhaps now is a good time for some interjection to keep me from going too far afield.

Or should I just go with the 'shed to studio' build? and if so is there a potential improvement by way of enclosing the perimeter of the footing/joist system(with ventilation considerations of course)? say for example cinderblocks filled with sand(haha, yes, fond of this idea).


phew, well, I hope I have enough information here to engage you all in a discussion. not to mention, I hope I hit all the posting rules thanks again for all you do here!

cheers!
-chanda

p.s. - I realize the proper build of the inner leaf(green glue sandwich, caulking et al) makes it salvage prohibitive. if I get enough use out the install it will have been worth it. I mostly want to retain the outer leaf roof and wall panels. just wanted to clarify that.

[boomchaka]

Hi again,

bumping this as its been more than 2 weeks. perhaps it fell thru the cracks
or maybe I overlooked a posting rule/missing information? please let me know.

thanks!
-chanda

[Gregwor]

Welcome to the forum!

It's almost as if this did slip through the cracks. This is the first time I've seen your post!

I'm totally unqualified to answer your questions, however I thought I would reply to let you know that your post has been seen!

A few thoughts:
- the sand type floor probably wouldn't be horrible acoustically (presuming you really made sure that no sand were to ever settle and ultimately create a resonant chamber underneath your sub floor wood). However, structural integrity-wise, probably not. Passing building permits, probably not.
- even though this is a smallish shed type building and not the pentagon, it will still possess enormous weight and require a very strong foundation. Remember, you live in California *earthquakes much?*
- your wall and roofing material visually looks like it has very little mass. As much you're hoping that adding an inner leaf to create an MSM wall, with very little mass on one leaf, you're damned near going to be working entirely with the single leaf mass law equation. It takes mass on both leafs to make the system work. Furthermore, that material looks far from air tight at it's joints. I appreciate the bargain shopping, and maybe it's great to use on the OUTSIDE of a framed plywood exterior, but your drawing implies that you are just wanting to set that stuff down on some roof truss. You can totally get a decent enough outer leaf mass with plywood. If you want crazy good isolation, you could use a few layers and even beef up between your studs inside with more plywood or drywall. Then you'll be off to the races.
- That material also could pass as having two leafs (the two metal pieces filled with the foam). So having that plus another leaf would make a 3 leaf system. However, since it looks so thin, it will probably act as nothing, acoustically speaking.
- I realize that your SketchUp is in it's infant stages, but have you considered your heating/cooling situation?
- It looks like you have windows in your plan. Nothing is better than natural light to life your spirits, but when you're on a shoe string budget and having a main goal of isolation, my first instinct is to tell you to ditch them.
- If you have to tear this sucker down, what's another few days worth of jack hammering a concrete slab out?
- You can build the inner leaf using the inside out technique and have a totally controlled/tunable room that should serve your purpose well.

I hope this helps!

Greg

[boomchaka]

Hi Greg, thanks for the reply! phew, I'm glad I didn't spurn the forums rule makers

regarding structural integrity, I have a tendency to overbuild so I am sensitive to the solidity of the structure. yes, especially
given my geography as we've had 3 low rumblers in the last 2 months I have since procured 2x14 tji joists that
I plan on running 16 oc perpendicular to long sides of the structure. here is a crude idea mocked up in sketchup for alternate
foundation. I'm curious what folks think.

cinderblock_foundation.jpg

I am thinking it would be a build of selectively pouring footings/embed block/fill w concrete inside block/embed sill plate bolt. fill remaining block cavities w sand. the lower row of blocks would be set down at least half their height into a trench with a bed of base rock in it then back filled and compacted around it all. also there would be z flashing at the base of the exterior of the outer leaf over the top row of block to keep water out. I would also lay in a vapor barrior. its probably crazy I know. I'm just not feeling 100% about pouring a slab then having to remove said slab. somehow the concrete block idea seems much easier to dismantle/reuse.

alternatively I am pondering setting the tji joists in a traditional manner(on pier block and beams) then skirting around the perimeter of the sub floor build with sand filled cinder blocks. essentially whats happening in the above image minus the lower row of wider cinder block/sill plate. but of course continuting to the ground to cover everything from the sub floor down

musings on the sandwich panels:

they are fairly heavy. the metal is steel. if I had to guess I would say they are as heavy if not more so than its equivalent in a 2x4 + sheating build. the joints get a bead of caulk in the grooves at install so I'm hoping that addresses the slop/air escapage there. the panels themselves do have a very cohesive assembly. each sheet of metal is heartily attached to the foam core. perhaps at inner leaf build time I line the insides of the outer leaf with soft insulation then do the inside out inner leaf with an air gap inbetween?

regarding the windows and heating/cooling:

yes, put those in because it is going to start out as a functioning 9-5 office space to start/as funds replenish for inner leaf build. I am in the redwood forest so any kind of light is a beautiful thing. but, so is making music without disturbing anyone. alas, such a tradeoff. was thinking of either matching them with soundproof glass in the inner leaf or 'boarding' them up and not putting windows in the inner leaf. as for heating/cooling I have a small furnace I will be hooking up in my shop. the furnace will be in an attached utility room that will end up approx than 6' from the proposed office/studio build. the furnace can easily handle both structures. but I haven't fleshed out all the ducting between buildings. that or a split system.

thanks again for your reply and breathing some life into it! any other thoughts are greatly appreciated!
cheers,
-chanda

[Gregwor]

Good work on the SketchUp Chanda!

here is a crude idea mocked up in sketchup for alternate
foundation.

As long as your plans are approved by your county and will pass inspection, cool. You have much more knowledge regarding building structures than I do!

Acoustically, one issue I see is that your TJI joists will create a resonant chamber for your floor. This is not good. The best floor you can have is just concrete. If you're not going the concrete route though, I suppose if you dampen that cavity the best you can, then that will be that. It will certainly be a weak point to both the tone of your room and the isolation around the resonant frequency of the cavities under your feet. To learn more about resonant cavities around your room, read the post Soundman2020 just wrote today here:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21422

the furnace will be in an attached utility room that will end up approx than 6' from the proposed office/studio build. the furnace can easily handle both structures. but I haven't fleshed out all the ducting between buildings. that or a split system.

Sounds good. Just make sure you have homemade silencer boxes on your inner and outer leaf of your sound room. So that will probably mean having two inside your room (supply and return), and two outside in the elements (supply and return). After that, you can do whatever normal ducting practices you want.

Keep us posted!

Greg