Octagonal small Studio plans for Studio in Thailand

Many thanks once again Stuart...Everything suggested has been noted. A few further questions; regarding the doors and doorway itself, I have checked all the links you kindly provided and have decided on going with two solid MDF doors, each of @50mm thickness ( made from two layers of @25mm MDF, I still need to check what is the thickest available here on the Island), surrounded by air tight/ rubber sealed door-frames, with a mechanical arm closer and magnets on the inner door. The outer door will lead to the outside of the building, therefore it will unavoidably need to have a handle, deadbolt ( ie hole drilled into it) etc. One thing that I'm assuming is that the gap between the doors will be sufficient as it will be the same as the gap between the inner and outer wall leafs ( approx 13")...Also I am assuming/hoping that the density of the 50mm MDF doors will be sufficient enough to maintain the same soundproofing characteristics as the building's dual wall MSM , therefore maintain the same isolation frequency of the total structure. I cannot really change drastically the gap between the doors , but can change the density of each door..Hopefully 50mm of solid MDF will be sufficient in this case.

What would be the best way to cover this 30 inch or so 'tunnel' from the outside wall to the inner doorway.

One idea: Wrap panels of 703 with some type of pretty fabric, and put them along the sides and top of your "tunnel". Unfortuantly this treatment wouldn't be too practical in this case as the air in the gap between the 2 walls will be both extremely hot and abnormally humid ( from ground moisture heating up in the day)... it's normally 30C all year around here and moisture runs at about 80-90% humidity most months, so this fabric and insulation would become sodden and moldy within a matter of days. I am trying to figure out a durable and 'solid' ( I use the word 'solid' in this case only as way of describing resilience) way of 'closing' off this tunnel, yet not induce flanking to the design..any suggestions please? Also from most of the information /links I have found and read regarding HVAC ventilation and silencing, most of what's around is primarily concerned with silencing the incoming air due to live recording requirements etc. Our studio will only be used for electronic music production ( i.e no need for any live recordings) therefore the the sound of the ventilator fan is not at all a critical factor to us. Of chief concern is soundproofing, therefore will we need to install insulated ducting and a silencer on the INCOMING air supply as well as having the Exhaust air system silenced in the suggested manner .? We are installing a 2.5 KW LG ductless split system AC unit combined with a standalone 15 liter Novita Dehumidifier, and there will be no windows built into the structure- therefore fresh airflow and stale air exhaust are very important, yet once again containing the sound inside is of the utmost importance. Also, from what I could glean from the forum calculations and also from other websites regarding commercial ventilation, I have calculated that a 350 cfm inline fan will be sufficient ventilation for the room size ( 440 sq.ft):- providing 2 people @ 6 airchanges an hour..( please confirm or dispute these calculations ?) Does the exhaust fan need to be of the same cfm rating, or even higher ..Is it better to be sucking more air in or out, or try to maintain as even a balance as possible? Whether or not one or two silencers are needed , I was thinking of mounting them (sufficiently isolated with isolation material) directly onto the the wooden framework of the inner wall ( top) and build short rectangular 6" by 8" MDF ducts directly out from the silencer box into the room, then 6 " flexduct piping with Inline 350 cfm fans from the back of the box to the outside air( same for the Inlet air supply yet with opposite direction fan)..Does this flexduct also need to have two 90 degree angles in it before exiting? (especially the exhaust duct) . Should the Inlet and Exhaust duct size be the same? ... ---

have decided on going with two solid MDF doors, each of @50mm thickness ( made from two layers of @25mm MDF,

That's about the same mass as three layers of 16mm drywall, so you should be OK with that. The most important point will be the quality of the seals.

surrounded by air tight/ rubber sealed door-frames,

You should have at least two full seals around the complete perimeter of the door. One really good option is a magnetic rubber seal, something like you find on refrigerator doors (except heavy duty).

The outer door will lead to the outside of the building, therefore it will unavoidably need to have a handle, deadbolt ( ie hole drilled into it) etc.

OK, but try to get a lock that has the smallest possible hole, and try to seal that hole very well, to minimize the loss in isolation.

One thing that I'm assuming is that the gap between the doors will be sufficient as it will be the same as the gap between the inner and outer wall leafs ( approx 13")...

Yes and no... The difference is that you can't fill that gap between the doors with insulation, as you need to walk through there! In the equations for calculating the resonant frequency of MSM systems, adding insulation is more or less equivalent to increasing the air gap by a factor of 1.4. So basically, the air gap in your walls is equivalent to 13" x 1.4 = 18", while between your doors it is just 13". But you can put thick insulation on the backs of the doors, to help with that. If you put 4" of insulation on the back of each door, that should be enough. So the big issues with your door plan will be seals around the edges, sealing the lock, and insulation in the gap.

Unfortuantly this treatment wouldn't be too practical in this case as the air in the gap between the 2 walls will be both extremely hot and abnormally humid ( from ground moisture heating up in the day)

:shock: :?: It might be hot, but there should be no "ground moisture" getting in there! The ground must be sealed with a membrane, before you pour the slab, even in the gap between inner and outer foundations. You cannot just have bare earth exposed there: it MUST be sealed some way. Also, since both leaves must be fully sealed, and your outer leaf is going to be massive, it should not be too hot in the air gap, I would expect. But regardless, if you think that that mold and mildew would be a problem, then maybe you can just coat the fabric with some type of chemical treatment? It wont make much difference, acoustically.

Our studio will only be used for electronic music production ( i.e no need for any live recordings) therefore the the sound of the ventilator fan is not at all a critical factor to us. Of chief concern is soundproofing, therefore will we need to install insulated ducting and a silencer on the INCOMING air supply as well as having the Exhaust air system silenced in the suggested manner .?

Yes, you still need that, as it is part of the overall isolation plan for the studio: It isn't just to treat the HVAC and silence the fan, but rather is to maintain the entire isolation of the studio. Without the correct ducting and silencing, you would be wasting your money with the rest of the isolation. The entire building is a system. All the parts work together.

Does the exhaust fan need to be of the same cfm rating, or even higher ..Is it better to be sucking more air in or out, or try to maintain as even a balance as possible?

The two fans need to be the same rating, and well balanced. Your studio is totally sealed airtight, except for the ventilation system, so the amount of air coming in must be the same as the mount going out. The two flow rates must be equal. If not, then the fans will be fighting each other: the small one will be forced to over-speed by the pressure created by the big one, and the big one will be working against too much resistance. They must be balanced.

Should the Inlet and Exhaust duct size be the same?

The total cross sectional area has to be the same. So for example, if you have four inlet vents of one square foot each, and two outlet vents, then the outlet vents need to be two square feet each, or one of one square foot and the other of three square feet. Once again, everything has to be balanced. You need the same flow of air going out as is coming in. - Stuart -

This is a very cool looking design man. I have built a couple of vocal booths but nothing to this magnitude. In my estimation though, depending on how populated the area is, it should hold up for the most part soundproofing wise. Unless you plan to record in a club area late at night where bass ripples often can find their way through anything. edit: corrected by xSpace to remove the link

Ian, what is your point? You seem to be confused: this is not a design for a vocal booth! Also, please check the forum rules for posting. You are missing something... - Stuart -

Yes and no... The difference is that you can't fill that gap between the doors with insulation, as you need to walk through there! In the equations for calculating the resonant frequency of MSM systems, adding insulation is more or less equivalent to increasing the air gap by a factor of 1.4. So basically, the air gap in your walls is equivalent to 13" x 1.4 = 18", while between your doors it is just 13". But you can put thick insulation on the backs of the doors, to help with that. If you put 4" of insulation on the back of each door, that should be enough.

Excellent tip!... So then we'll plan on framing 2 times 50mm 703 spec( Fibertex 650) rockwool on the back of each door, with speaker fabric covering, very similar to the bass traps we will be constructing for the room itself. For the 'tunnel" between the two doors;...once again we'll heed your great advice Stuart, and use the same #703 type insulation covered in speaker fabric with a moisture treatment applied to it. Would semi rigid fiberglass be the only suitable material to use here? I'm assuming the more rigid/dense a material is, the less effective a decoupler it will be..? I have some @inch thick hi density black rubber laying around, and was thinking of using that in this gap as well, to keep these 'tunnel' walls straight and true..but of course will not end up using this, if it will affect the leaf isolation in any way.

Would semi rigid fiberglass be the only suitable material to use here?

Well, you could probably use mineral wool, or fiberglass insulation, but it won't stand up by itself like 703 does, as it isn't rigid enough: you'd have to build some type of frame to hold it in place, but that would work fine too.

I'm assuming the more rigid/dense a material is, the less effective a decoupler it will be..?

Exactly!

I have some @inch thick hi density black rubber laying around, and was thinking of using that in this gap as well,

It might be OK... or it might not. If you don't have the acoustical specifications for that rubber, then it would probably not be a good idea to use it. - Stuart -

ban sabaii wrote:

Double Leaf wall construction> Inner Wall constructed on top of a decoupled concrete slab ( i.e decoup. from Outer wall Slab) 2 layers 5/8 " Plasterboard 1" OSB 50mm # 703 12 " Air gap stuffed with 6" R38 rockwool ...

Today i readed a interesting information on the manufacturer site of plasterboards and recognized on your building project: http://www.rigips.de/de/3/0/875/seite_1/Aktuelles/Topthemen/direktbefestigung_von_gips_auf_holzwerkstoff_platten.html this is in german and they say you might get cracks in the future if you put plasterboard on OSB or any wood type material. The problem is the different expansion on air humidity influences. You simply need to put one kraft paper between the osb and plasterboards or simply a PE-foil. Would be a pity if you caulk everything and after some years you recognize cracks on the plasterboards. best aaron

You simply need to put one kraft paper between the osb and plasterboards or simply a PE-foil.

Unless, of course, you already have a proper vapor barrier in place, in which case that might not be such a good idea. - Stuart -

i forgot to translate they mainly talk from the areas the plasterboards are connected and where you are jointing the holes. The paper or pe-foil would only prevent the caulking gets in touch with the OSBwood and plasterboards. I think you could just use foil tripes behind these connections for avoiding cracks on this plasterboard connections (first plasterboard layer). Does it make sense to do so?