Wife has given me the carport - need help with design

My name is Paul, from Adelaide, South Australia. My wife has just decided to annexe our 16x9' detached shed for herself (this was going to be my TINY one-room studio) and has given me the carport for my studio instead for a two-room approach! The intended purpose of the studio is for recording of live drunken jams with my buddies, and occasional commercial work as a demo/low budget studio. The house is a 1977 brick veneer (AV Jennings Homes, for the Australians here) with a carport under the main roof open on 3 sides. The roof is of the Hip (is this the correct term?) tiled "A" frame variety. Carport is 8.5m long (length of slab) by 2.9m wide (width of slab) by 3m high (slab to weatherboard ceiling). The brick veneer side has ventilation bricks spaced evenly along its length, approximately 50cm above the slab. The long side opposite the brick veneer has 4 box steel uprights which support the main roof. Attached to the uprights on the exterior side is galvanised sheet (standard Aussie tin shed stuff) which covers roughly 75% of the long open side - this can be removed if neccesary. The property line is approximately 1m from the long open side and must remain accessible for garbage bin access and as a bushfire escape route. The two short sides are completely open, one faces the driveway and the other faces the back yard. The main entry door must be on the driveway end to facilitate loading of gear into the live room from vehicles. There may be a door on the back yard end, but it's not crucial. I envision having the control room at the backyard end and the live room at the driveway end. It would be nice if I could have control room access from the backyard but not strictly necessary. I'm not fussy about the actual dimensions of the two rooms other than that they possess the best possible acoustic dimensions given the space allowed, and that the live room should probably be the larger of the two. The live room will need to accomodate a drummer, bass player, hammond organ & leslie, guitarist with Marshall stack, and maybe a singer in the control room. There are no neighbours to speak of except for those on the long open side, their house is approximately 8m away. I have metered my Marshall stack on "11" played inside the nearest room to the neighbour's house and it metered at 70dB at the property line - this is in an untreated house with the amp metering 112dB in the room itself. The neighbour fires up his chainsaw on a regular basis and I've metered it at 60dB in my backyard, so there won't be too many noise complaints from him I don't think! I would be happy to get the noise at the property line down to 50 or 60dB from a rock band in the live room. I am not concerned about the sound transmission into the house itself (wife already tolerates cranked Marshall before 9pm most nights). Having read Rod's book, I imagine the following construction method: On the 3 open sides there will be a 2 leaf stud wall with independent top and bottom plates (i.e. completely decoupled). The long open side with the 4 box steel uprights presents a few options, but for the sake of simplicity I think it best to ignore the uprights and simply build the stud wall on the interior side of them. Exterior will be covered in weatherboard ("blueboard" in Australia). Interior will be 1 or 2 layers of plasterboard, with semi-rigid fibreglass insulation in the cavity (I have sourced OC-equivalent from Fletcher Insulation in Australia). Green glue will be used if 2 layers of plasterboard are implemented. Ceiling will sit on joists resting on the internal stud walls so as to be completely decoupled from the carport ceiling above. OC-equivalent fibreglass in the ceiling and a single plasterboard layer. The brick veneer wall has got me confused - is the best option to ignore the brick wall altogether and construct a 2 leaf stud wall the same as the open sides of the carport? - this would allow the ventilation bricks to function properly if the stud wall were say, 20cm away from the brick veneer wall, although this would eat into the available floor space. Other options? use the brick veneer wall somehow? - I don't know what kind of loads such a wall can handle. The live room and control room will be separated by a decoupled 2 leaf stud wall with OC-equivalent in both sets of studs. A soundproof door will be needed to join the live and control rooms. I intend to forgoe the traditional control room window and use video cameras instead for visual communication with the live room - thus saving the expense and headache of constructing a proper soundproof control room window. I won't have the budget nor the construction skills for angled walls and ceilings, unfortunately it will have to be straight lines all around. The rooms will be treated with fibreglass bass traps in the corners and clouds in the ceiling, with foam or fibreglass absorption panels on the reflection points and trouble spots. I figure I can add and modify treatments ad infinitum as more money becomes available over time, I just don't have the funds to build nice angled walls initially. HVAC will have to consist of in-wall reverse cycle air conditioners in each room, probably on the two short end walls - there's no budget or space for anything more elaborate here. The floor is a standard Australian concrete carport or driveway slab. It appears to be a separate pour from the house foundations, separated into 3 equal sections - I don't know if the 3 sections are physically decoupled and if the slab is decoupled from the house. I intend to carpet the slab or possibly lay bamboo tongue-in-groove boards directly on the slab and use rugs for shaping the reflectivity. As far as council approval is concerned, I have 5 cars' worth of parking on existing driveways, and many of the houses in the neighbourhood have built-in their carports and garages, so I don't forsee any objections to my project other than the lack of windows. My budget is limited - keep in mind the original project was for a 16x9' tin shed, no more than $5k for that one! I should be able to stretch to $10k maximum for this project, wife willing :) I am able to undertake some of the construction myself, eg. installing insulation & plasterboard, and constructing bass traps, clouds and absorbtion panels. I can get all of the electrical work for free from a qualified HT electrician (he works every day on 400kv systems in underground mines!, 240v is like relaxation for him). There is potentially a dedicated 30amp service available for this studio. I can get "mates rates" for the construction of the stud walls, hanging of doors, etc etc. My original calculations for materials for the 16x9' shed came to roughly $3k, and this project is akin to two 16x9' rooms, therefore I think $10k should cover things. Basic Sketchup iso plan is attached (JPEG) I don't know how to shrink my Sketchup file down to 500kb, sorry. I truly appreciate any feedback, criticisms and advice on my project - I only have 1 opportunity to plan and execute this the right way! I am in no hurry to commence construction - funds are still coming in, and I want to get this done properly, not hastily. Kind regards, Paul

if the brick veneer could be sealed and had sufficient mass you could use that as the outer isolation wall. maybe post some photos of it. if not, then you might just create a single frame wall with exterior board outside and isolation clips and hat channel/furring strips w/ drywall + GG on the inside. this would preserve space. if the brick veneer wall is suitably ventilated then it shouldn't have too much of a third leaf effect.

gullfo wrote:

if the brick veneer could be sealed and had sufficient mass you could use that as the outer isolation wall. maybe post some photos of it. if not, then you might just create a single frame wall with exterior board outside and isolation clips and hat channel/furring strips w/ drywall + GG on the inside. this would preserve space. if the brick veneer wall is suitably ventilated then it shouldn't have too much of a third leaf effect.

Thanks Glenn. The brick veneer wall is well ventilated via ventilation bricks (metal grilles same size as a brick, built into the course just below the house floor level.)

UPDATE: MASSIVE change of plan! Due to imminent arrival of baby I was forced to wall in the carport very quickly in order to free up a room in the house for baby's nursery and get my gear out of the house. My wife did a great job rejigging the finances to get the job done ($7,000 for the walls). So, I now have a structure on the carport slab consisting of 1 wall brick veneer (existing exterior wall of house) plus 3x stud walls (2x4's at 600mm centres) with cement sheeting exterior cladding (Harditex Blueboard) with foil insulation/fire shield on the inside face of the cement sheeting. The inside dimensions of the room are 8m (L) x 2.9m (W) x 3.17m (H) (this is measured to the inside face of the studs and to the face of the existing fibreboard ceiling). The bottom plates rest on moisture barrier and are dyna bolted to the slab. The vertical studs are dyna bolted to the brick veneer. The top plates are tied in to the existing rafters which support the main roof of the house. On the north wall (2.9m W x 3.17m H) there is a solid core door in a frame which I specified must be able to support a second solid core door later on. Also on the north wall is a window consisting of a single 6mm laminated pane sitting on the exterior side of the sill so that a second pane can be added on the inside of the sill later. All work was carried out by a licensed builder with council approval. I've decided not to split the space into two rooms. Budget is very tight. Here's my strategy for isolation as an initial short-term goal so I can actually begin to use and enjoy the space: 1: Seal every single crack and hole in the exterior structure with polyurethane sealant (including filling brick vents with expanding foam and sealing with polyurethane). 2: Beef up outer leaf with 16mm dry wall glued and cleated between the studs, seal with backer rod and caulk. 3: Rockwool insulation (30kg/m^3) between studs. 4: Electric cabling installed by licensed electrician: 1x 10A circuit for computers & recording gear, 1x 10A circuit for musical equipment, 1x lighting circuit (2 of these circuits are already run to the room as standard carport items). Computer circuit will be on its own surge protector at the house's main board. 5: 2x layers of 16mm drywall hung on RC on the 3 stud walls & ceiling, Green Glue between layers. 6: Surface-mount electrical boxes installed and caulked 7: Door seals installed (Bank vault seals and bottom door-actuated storm/acoustic seal) 8: Ventilation will consist of an eave-mounted fresh intake ducted to a silencer on the ceiling joists fan-driven to a ceiling-mounted register. Stale outlet will be a passive silenced duct out to the eave on the opposite end of the room. 9: Airconditioning will simply be pedestal fans (doesn't get too hot where I live) and a portable column radiator in winter. 10: Lighting consists of 2x existing ceiling-mounted bulbs on 500mm droppers and floor-standing lamps for ambience. The openings for the ceiling cables will be caulked. I'll be happy if I can get a 100dB guitar amp isolated down to about 50dB at the property line. The neighbours are fairly easy-going but that might not always be the case. I'd like to be able to mix at 85dB comfortably until about 1030pm without disturbing the neighbours. I believe local noise regulations call for 40dB at the property line (usually applicable to airconditioners, etc.). There is a relatively busy semi-rural road behind the property which has frequent truck & tractor traffic - I've metered this at about 40dB inside the house, therefore any noise I make will not compare to the road noise as far as the neighbours are concerned. The traffic tends to run from about 7am to 11pm - roughly 1 vehicle every 5 or 10 minutes. I'm hoping to achieve a high degree of isolation from the road noise affecting the studio. OK, on to the acoustic treatment strategy: 1: Floor to ceiling superchunks in the 4 corners 2: Broadband Rockwool framed absorbers sitting an inch or two proud of the walls (I will experiment with placements and quantities until I'm satisfied). Primary reflection points for the mix position will be treated using the mirror method. 3: Hard backed framed Rockwool clouds above mix position at one end of room and above drum kit at other end. 4: Broadband Rockwool framed absorbers along the wall-ceiling junctions at 45 degrees. (Will only do this if the primary treatments are insufficient). 5: Mix position is 38% off the rear wall (opposite end of room to door & window). 6: Speakers are on stands, 1.2m high, about 0.5m from wall (Tannoy near-fields, can't remember the model, they're in another house at the moment). 7: Wall behind speakers will be covered in absorption panels 8: Flooring will be tongue-in-groove laminate with an acoustic dampening layer (off-the-shelf product, claims 20dB reduction in impact noise). 9: Rugs as portable spot-treatment on the floor. 10: Drum riser on neoprene and stuffed with Rockwool. 11: Couch riser same as drum riser. 12: Maybe an amp riser if the drum riser performs well. I've read Rod's book several times and continue to reference it during this planning stage. Also I've been a long time lurker on this forum and have gained invaluable insight from the many experts here. It is safe to assume that from this point on all construction methods for isolation as outlined in Rod's book and this forum will be adhered to in regard to dampening, sealing and at all interfaces - as I progress I hope to post updates with photos and diagrams for the experts here to critique. I know my build has not gotten off to the best start being rushed into existence, and I know a box isn't exactly the best shape, but it's what the rock and roll gods have given me. I do not have the budget for splayed walls, slot resonators, soffits and the like :( The primary purpose of this room is so I can crank my Marshall and jam with bands during the hours of 9am to 10pm. I don't need 70dB or even 100dB of isolation in adjoining rooms - I just need to take most of the edge off so it's acceptable to my neighbour (i.e. 40dB at the property line and inaudible in his house). I know it might be a long shot to have a full band at 10pm without disturbing the neighbour - that activity might have to be limited to 9am-6pm, but at the very least I'd like to be able to crank the Marshall from 9am to 10pm. OK, the questions: 1: Will my isolation strategy achieve what I'm hoping for? 2: I've found an inline duct fan capable of 4.6 total room changes per hour for my given cubic airspace - is this sufficient for up to 6 persons in the room? 3: I know, I know - I'm stuck with a box..... any suggestions to correct or re-arrange my treatment strategy? 4: Any suggestions, anything at all which immediately concerns anyone which might cause me to STOP NOW and re-evaluate before picking up a single tool. Thanks all! Paul :)

I took some readings on the unfinished studio. The structure is single stud wall (2x4's 600mm centres) with cement sheeting, that's all. The readings seem to concur with much of the online data from manufacturers and researchers. FFT plots using iPhone AudioTools: