A few questions about a studio build project

Hey, I will be relocating to France in 6 months and will be building a new studio. The purpose is essentially mastering (my main business), but I also want it to host a few instruments and occasionally be used to produce some music. I am considering two options: 1. Build a room inside the existing detached, underground garage Max possible dimensions: 530cm x 440cm x 245cm Pros: cheaper - naturally soundproofed (underground) Cons: smaller (ceiling is actually slanted: highest 250 lowest 240) - no natural daylight This would be in the back of the garage there: 2. Build a studio above the underground garage Max possible dimensions: 560cm x 470cm x 280cm Pros: larger - possible to get some natural daylight Cons: more expensive to build - needs some soundproofing This would be roughly where the children's wooden shack is there: Solution 2 would have my preference because the max dimensions for solution 1 are not great, especially the ceiling height. However I might not be able to go ahead because the project is subject to approval by the government (I live in a protected area). Now here are my questions: - Are there any other pros/cons that I might have forgotten for either one of the options? - What is the best way to make windows work without screwing up the acoustics in option 2? (position, shape and size) - In option 2, is it preferable to have a flat horizontal ceiling or a classic gable roof? - Again for option 2, what are the best solution (materials) for the walls, acoustic-wise? Thanks to anyone who takes the time to read and provide answers!

What a beautiful looking location. What are your soundproofing requirements? We need a number, spectrum even, on that? A light building above ground with a higher ceiling will be a lot easier to treat sonically, but a lot more difficult to keep sound/noise out or in. Insulation is not Isolation....

Thanks DanDan! Yes it's a nice place. Although I know a fair deal about acoustic treatment, I know almost nothing about soundproofing. My only requirement is that I don't bother my neighbors (I often work late at night). In terms of noise from the outside it's not really a problem, the place is quiet and I will only record every once in a blue moon. I just need to make sure the neighbors can't hear my monitors (I monitor around 80 dB SPL, often less, very rarely more).

Your outside environment is amazing. I would opt for maximizing that. If you own the property isn't there a way to build it without the government knowing? (I had to ask)

Haha, no this is going to be on Google Maps anyway so there's no way... The village I live in is tiny and remote, but there is a castle and we are in a nature reserve so that's a lot of reasons for the government to pay attention to what we build. I did have the underground built so I successfully obtained a permit once, I might get another one.

Okay so I'm working on option 2 (outbuilding). I've designed a simple model as a starting point, but it's really just a draft since the plan is to hire an acoustician for the design. The length is fixed (because the building is going to rest on the underground garage so it has to fit its shape) but the width and height can be adjusted within what the regulations will allow. https://i.ibb.co/WWq3hxM/studio-condec-v1-0.jpg Does this look like a good starting point? Any particular thing I should pay attention to at this stage?

so far looks good. planning for hvac is usually something most folks overlook but should be done early. the glass block is nice but may not offer as much isolation as two heavy glass panes - you want to try to match density & mass compared to the walls and ceiling. speaking of ceilings - this is often a weak area for isolation and it essential "broadcasts" sound (as well as receives - like rain noise etc) so ensure the isolation mass there is consistent as possible with the walls.

Very good points, well noted. Thanks!

gullfo wrote:

so far looks good. planning for hvac is usually something most folks overlook but should be done early. the glass block is nice but may not offer as much isolation as two heavy glass panes - you want to try to match density & mass compared to the walls and ceiling. speaking of ceilings - this is often a weak area for isolation and it essential "broadcasts" sound (as well as receives - like rain noise etc) so ensure the isolation mass there is consistent as possible with the walls.

Hey Glenn, What are some examples of your go-to built up roof/ceiling assemblies when trying to compete with the surface density of concrete block? (And, when formed concrete/block and beam are not practical options)

for ceilings where you don't have an option for significant mass (like a layers of steel reinforced concrete or even heavy SIP panels) i often use triple leaf and quad leaf to get there with large air gaps (attic space) which significantly offsets the TL issues with triple leafs. for example one project - we used Tectum for the interior absorption on the ceiling joists, 3x gwb on top of joists, then exterior mass layer on rafters (about 3ft air gap) 3x gwb, and in-between rafters another 3x gwb as mass enhancement on roof sheathing. near silence from the roof even with the band cranking 120db. however, not all projects can support this level of mass - we were lucky that the rafters were steel. in a situation with wood - i'd use less on the mass enhancement (which in another project) the interior top mass was only slightly damped, acting as a membrane absorber. so we have 3x gwb, 1x inner mass, 2x gwb, 1x 1" sheathing on a seismic resistant structure. again - cranking 120db, near silence just outside the door (weak point) and zero by neighbor 5' away... sometimes the "triple leaf" effect can be used to provide some gain in TL but i'd say it's a bit more luck than purely computational as products and construction can move from ideal to bad fairly quickly...

gullfo wrote:

for ceilings where you don't have an option for significant mass (like a layers of steel reinforced concrete or even heavy SIP panels) i often use triple leaf and quad leaf to get there with large air gaps (attic space) which significantly offsets the TL issues with triple leafs. for example one project - we used Tectum for the interior absorption on the ceiling joists, 3x gwb on top of joists, then exterior mass layer on rafters (about 3ft air gap) 3x gwb, and in-between rafters another 3x gwb as mass enhancement on roof sheathing. near silence from the roof even with the band cranking 120db. however, not all projects can support this level of mass - we were lucky that the rafters were steel. in a situation with wood - i'd use less on the mass enhancement (which in another project) the interior top mass was only slightly damped, acting as a membrane absorber. so we have 3x gwb, 1x inner mass, 2x gwb, 1x 1" sheathing on a seismic resistant structure. again - cranking 120db, near silence just outside the door (weak point) and zero by neighbor 5' away... sometimes the "triple leaf" effect can be used to provide some gain in TL but i'd say it's a bit more luck than purely computational as products and construction can move from ideal to bad fairly quickly...

Thanks Glenn, you've confirmed a few of my thoughts on this. Before I comment further, I am interested in what you do for cold roof systems when it is required to have a 50mm ventilation channel between every rafter pair, open to the outside world?

i leave the air gap in place and build mass before that - i've seen there are prefab panels which can provide the standoff for the vent channels and then attaching the mass. not used them but in the future when a project requires it, i'll spend some time investigating options including costs, structural capacity, etcv.

gullfo wrote:

i leave the air gap in place and build mass before that - i've seen there are prefab panels which can provide the standoff for the vent channels and then attaching the mass. not used them but in the future when a project requires it, i'll spend some time investigating options including costs, structural capacity, etcv.

Exactly, this is what I have been doing on all my builds (unless there's a warm roof). Do you also insulate above those added mass layers? Something like this: Roof Deck Ventilation channel Insulation Outer Mass layers Insulated Air gap Vapour barrier Inner Mass Layers

no. that's pretty much the layering of materials and insulation.

gullfo wrote:

no. that's pretty much the layering of materials and insulation.

So, you don't insulate above the outer leaf mass layers (below the ventilation channel)... Interesting.

no. :-) i don't insulate between the roof deck and ventilation channel as shown in your list :-) Roof Deck >> no insulation << Ventilation channel >>Insulation<< Outer Mass layers >>Insulated<< Air gap Vapour barrier Inner Mass Layers >>acoustic treatments<<

gullfo wrote:

no. :-) i don't insulate between the roof deck and ventilation channel as shown in your list :-) Roof Deck >> no insulation << Ventilation channel >>Insulation<< Outer Mass layers >>Insulated<< Air gap Vapour barrier Inner Mass Layers >>acoustic treatments<<

Great, actually, that's exactly the same as what I wrote :D in any case, glad to know I am doing it correctly

Paulus87 wrote:

Great, actually, that's exactly the same as what I wrote :D in any case, glad to know I am doing it correctly

yes, copy and paste are wonderful! ;-)

gullfo wrote:

Paulus87 wrote:

Great, actually, that's exactly the same as what I wrote :D in any case, glad to know I am doing it correctly

yes, copy and paste are wonderful! ;-)

hehehe, was good to chat to you yesterday Glenn