Over ambitious

[midgeybin]

I have 3000 sq feet of space to convert into rehearsal rooms.The existing walls are timber stud, roof and floor are timber joists. I will be building rooms within rooms off floating floors ,with 4x2 timber studs and 2 layers of gyproc on resilient channels, rockwool etc.Can I achieve satifactory sound insulation for bands to practice given that the rooms are 2 feet apart ,1 foot of insulated wall to each room with a further 6 inches of air gap between.Apologies if I have posted this query before but my main question is can it be done?

[knightfly]

Hi, midgeybin - my main question is, if this is your very first post, how could you have posted this question before?

Seriously, could you please update your profile with a location? It's tough enough making suggestion without finding out that the materials aren't available or cost effective in your part of the world -

Second, I'd need much more specific info on your site - type/size/spacing of existing floor joists, support spans, preferably a drawn plan layout, your approximate budget, building skills, help available, and anything else that might clue me into your situation.

That being said, if you're willing/able to separately float floors, walls, and ceilings, and allow up to two feet between rooms, you may be able to get over STC 60 in everything but doors. Those will add considerable expense if you want that high isolation, but a proper design that ensures two doors between each space could preserve that isolation value... Steve

[midgeybin]

Thank you for the reply.The studio is situated in Glasgow city centre ,Scotland.Its on the 3rd floor of a 4 storey building with offices above.Joists are at 600 centres.The attached plan shows existing timber stud partitions .I intend to build rooms within rooms either side of these walls on floating double ply floors.The cielings will also be lowered ,5/8 gyproc on resilient bars mounted on 100x50 battens fixed to existing gyproc ceiling with rockwool infill.Will this be sufficient soundproofing for offices above?I have enough headroom ,11 feet, to drop the ceiling further.The walls in blue are the only ones being built without existing walls between .Would it help to build a new wall from floor to existing ceiling with new rooms inside as elsewhere.My budget is £40,000 which I calculate will pay for materials and labour.Im fortunate in having family in the building trade and the savings through them for materials are substantial.Previous experience has shown that I need to monitor their joiners at all stages though,they love nailing gyproc to studs

[midgeybin]

This is how I intend to build each of the six rooms.In addition each room will have solid doors fitted to both stud partitions.I have had rehearsal rooms and a recording studio before and found it really difficult to contain low frequencies using timber walls.Will this type of construction make it possible for bands to practice in adjoining rooms.

[knightfly]

There are a number of considerations when designing multiple sound proof rooms, such as being careful not to inadvertantly build in triple leaf walls, which would cost more and give less isolation. Your diagrams don't show whether you intend to repeat your wall construction in each room, or just one side of the divider between rooms - the first way would likely end up a triple leaf construction, as in more than one air space and more than two centers of mass between isolated areas. This is counter productive. It also puts more stress on the existing floor system.

Speaking of which, you don't show what the floor joists are like, nor where they are - the only SANE way to go about what you want to do, is to hire a qualified architectural engineer and explain what you want to do as far as your floated rooms, and let him inspect your premises firsthand. He will want to check the "as built" plans for the building, and verify whether the loading introduced by your new construction is allowable within safety margins or not.

This is NOT something you can finalize over the internet, especially on the third floor of a multi-tenant building.

As far as the actual sound proofing, you will likely need 3 layers of gyprock per leaf of 2-leaf partitions, deeper air gap on floors, and a close watch on flanking paths - otherwise, you will still have problems with low frequency isolation. Extra mass in the floated floors will help, but again you are talking about a large amount of weight on a floor that was likely NOT rated for it. Even basement floors with concrete under still need extra footings poured under walls when they get heavier than just an "office" partition -

Please, consult an engineer rather than chance killing someone... Steve