Garage into live room

Hello, First off I'd like to thank everyone for doing a great job on this forum. It's helped me a lot. Now, I'm building a live room inside my garage and I have a couple questions on the room ratio/splayed walls. I want to achieve the best sounding room with the small space I have to work with. I'm not asking about acoustic treatment or sound isolation but just about the design of the room dimensions. This is my first build and I feel as if I need to get the green light before I get underway. My design uses the 1: 1.60: 2.33 ratio giving me 8'H x 13'W x 19'L and from there I splayed my walls at 12˚. My question is: In a room this small, would it be more beneficial to keep a rectangular room with the exact recommended ratio without splaying the walls? Should the flutter echo and such be controlled post build with acoustic treatment? I understand that there is no calculator to determine room modes on non-rectangular rooms. Below are 2 sketchup drawings. The first is the original room ratio with splayed walls. The second is the garage space I have to work with (19' 8" x 18' 8"). I can only get away with an 8' ceiling due to joists. Thanks for any advice.

On a side note... Would it be beneficial to cover the interior of the brick wall with insulation? I'm guessing it would create a better STC rating with insulation on both sides of the air gap but I"m not 100%.

Hi "notes2k", and welcome! :)

My design uses the 1: 1.60: 2.33 ratio giving me 8'H x 13'W x 19'L and from there I splayed my walls at 12˚.

You say you are building a live room, not a control room, so ratios are not as important here. As long as your ratio is far away from the bad ones, you'll be fine. You also don't need to splay the walls like that.

My question is: In a room this small, would it be more beneficial to keep a rectangular room with the exact recommended ratio without splaying the walls?

I would keep it rectangular, or close to rectangular, in order to not waste space.

Should the flutter echo and such be controlled post build with acoustic treatment?

Yes. You could splay one or two of the walls by a much lesser amount if you want, to help with that. For example, you could splay one wall "out then back in", in an inverted "V" shape: that wastes much less space than splaying the entire wall.

I understand that there is no calculator to determine room modes on non-rectangular rooms.

Well, it can be calculated, but not easily. It requires sophisticated FEM/FEA computer programs, and an experienced operator to set up your room model in the software, set up the boundary conditions, run the analysis, the interpret the results for you. Expensive, complicated, and absolutely not necessary.

Would it be beneficial to cover the interior of the brick wall with insulation? I'm guessing it would create a better STC rating with insulation on both sides of the air gap but I"m not 100%.

More insulation means more damping on the cavity resonance, which is good. So yes, that would help PROVIDED THAT the overall isolation system is correctly designed and properly built. In other words, that both leaves are totally sealed, hermetically, and that they are also full decoupled, with enough mass on each and a large enough air gap between them. Also, STC is a lousy way of measuring studio isolation: it does not take into account low frequencies. - Stuart -

Thanks for your thorough response! I guess I will go with a rectangular room as big as I can get away with and add the insulation against the brick wall. Now, I just need to decide on a way to control temperature and ventilation (which is a lot harder to plan than I expected). Does anyone have any recommendations from experience on the best way to handle the HVAC in a situation like mine? There are many obvious ways to deal with the heating/cooling, but I'm still unsure on how to handle the ventilation. Is there some sort of unit that can handle both temperature control and proper ventilation or do I need two separate systems? A dual hose portable A/C apparently doesn't bring in a sufficient amount of fresh air and it's loud, so that's ruled out... I like the idea of a ductless mini-split for heating/cooling but again, that leaves me with no ventilation... Please help! This is only for 1 room so I don't want to go overboard but I want it to be efficient. The dimensions are 17' x 15' x 8'. Again, it's a room inside a room with brick exterior. The climate here averages from 38˚ - 95˚ F. My goal is to find a solution that is cost effective.