Concrete perimeter wall

Yiannis, is it possible you could post any pictures of this type of roof, or at least an idea of how strong those steel rafters are, and how far apart? It's looking like you may need to suspend a double-leaf ceiling INSIDE your normal roof and seal that to the perimeter walls. The only way I know of that you could get away with NOT ventilating your roof (and thereby making it act as your outer leaf) would be if you could somehow hermetically seal the outer roof tiles to the outer concrete walls, and then somehow circulate inside air through between them - but if you do that, then the space between outer and inner leaf is not sealed, and won't be nearly as effective to block sound. If you can find a way to post a more complete description of what you want to do for a roof, I'll try to determine whether it can work for a studio situation - otherwise, you may need to look at other ways of accomplishing your isolation needs... Steve

Steve,I don't have any pictures of the roof because it isn't constructed yet.I could only make a draw for now. I trying to figure out-with your precious help-how to build the outer shell as good as possible, so I will not have any problems later. All I know is that the steel rafters gonna be strong enought and the space between them could be anything from 50-70cm. My thought was to put a 10cm rockwool with 3 layers of drywall under the roof (on the steel rafters) 1st leaf I guess. beneath that I could live 50cm-1m space for the AC ducts and then the second roof could constructed on the floating floor.2nd leaf. Is it a good idea Steve or just a waste of time and MONEY? thank you!

Yiannis, when I asked about pictures of this type of roof, I meant maybe you had seen OTHER buildings built this way, and might be able to post a picture or two of how they are constructed - if not, drawings work much better than words most times - if you can show what you have in mind with the roof construction, including where each leaf would be and how the wall's outer leaf would be continued in the roof, and how the wall's inner leaf would be continued in the roof, it would help me understand what you have in mind. If that isn't possible, I might be able to find time for a couple of drawings in a couple of days, but right now things are pretty hectic so it may be longer... Steve

Steve,please let me know if this kind of draws are helpfull. Its a rought draw, so please forgive any drawing imperfections. I will post more details. thank you!

Yiannis, I have been doing some research on construction in the Mediterranean - and Steve's concerns regarding attic ventilation are very real. Due to the huimidity levels and temperature ranges in the Med - it is very important that the bottom of the roof be ventilated if you are going to construct what you've indicated. If you don't want to do this - then your construction will have to change somewhat. If you were to insulate between the roof deck and the bitumen layer with 3 or 4 inches of foam insulation (made specifically for this purpose - they have a board applied to the insulation for laying the bitumen over) then condensation won't be a probelm - but shy of that - you have to ventilate this space. Rod

Rod, you are right about that foam.Sorry I forgot to mention. What I don't understand is why the roof should be ventilated if it is air tight.Or it can't be air tight! If the roof can't be use as the outer leaf for the isolation then it's no reason to use ceramic tiles because are expensive. I mean I can use a simple roof for protection only, as Steve mention, and then construct 2 leafs. thank you

Yiannis, you are seeing why we like to have long, drawn out conversations with members before making final suggestions as to ways of doing things - in your last post, you mentioned that it would be no use to have the ceramic tiles if that roof wasn't going to be the outer leaf, which (as you rightly pointed out) it couldn't be one of the leaves if it's ventilated - My understanding of your idea just improved a lot with that statement - the answer is, you can't have both - either the roof is part of your sound proofing and is airtight (needs insulation where Rod stated or major condensation problems) or else you do as you stated and build the two leaves and use the (ventilated) roof just for weather protection. Personally, I think there are much cheaper ways of doing a heavy outer mass leaf than using ceramic tiles - unless you just like the way they look, I think you could do better from a performance standpoint - for example, a reinforced concrete slab with cast-in rafters would have higher mass than ceramic tiles (unless they're 150 mm thick) and therefore give you better Transmission Loss at all frequencies - then, any relatively inexpensive roof would serve as weather protection, and your sound isolation would not be compromised. Part of your decision may be swayed by architectural design, too - if the rest of your place has ceramic tile for roofing, you may want to continue the theme, etc - the more info you give, the better our understanding of your situation and the closer we can come to a plan that works for you... Steve

I tried to add something yesterday - but the site wouldn't let me log in - so will try today. Even if you add the insulation (which WILL take care of any condensation issues) the proposed roof is not going to be (IMHO) a very good outer leaf for sound isolation purposes. In order for a system to work properly it's needs a number of things as a part of it's construction. Mass Sealed Joints/Seams Structural Isolation. Etc......... Your outer covering may work from the point of view of mass - and structural isolation (if you build a room within a room) but it will not meet the sealed joints / seams requirement. The joints on the roofing - both horizontally as well as vertically will allow the easy passage of air currents - and thus sound. Effectively the bitumen barrier will wind up being your true sealed barrier - So although you might get some benefit from the added mass - I do not believe you are going to re-coup the added costs involved. Rod

Steve,Rod I think that finally the ceramic tiles roof will be not constructed. The reason is that it can't be a part of my insulation and 2nd its too expensive! maby a flat roof is better. I don't know if I can use a roof made from concrete. Are there any proposes for roofs that I can use as the outer leaf of my insulation? Except concrete are there any alternatives? thank you!

Yiannis, you mentioned that the space you're using is already the roof of an existing building? What type construction is that roof? It would help if we knew more about what is normal in your part of the world - it's possible that you may already have a solution that we can just add to... Steve

Steve, The existing roof(my future studio floor) is made from 13.5cm concrete with irons inside. Hope this helps. thanks

OK, if this is strong enough to support your interior walls, etc, why not just duplicate that construction for your outer ceiling's mass layer? Is the existing roof flat, and then covered with a waterproofing covering, or what? Acoustically, that would work fine for your outer shell - then an inner shell that's supported on the inner walls would round out a mass-air-mass system for you... Steve

Steve,the existing roof is flat and waterproof. take a look at this please www.mdue.it/maneggevolezza_eng.htm Maby is a good solution for my outer shell. I have send an email and waiting for the STC numbers . Its a sandwich panel with 12cm concrete in the middle. The best is that there are no joins anywhere.Roof and walls are one! Better to read it, you'll understand much more than I can describe in English. thank you!

Yiannis, this is almost identical to the system I'm planning for my next facility - here in the US, it's referred to as "ICF", or Insulated Concrete Form, construction - I would estimate that if/when they give you an STC rating, it will be somewhere between 50-55 depending on surface finish. If you do that for your outer shell, then build an inner shell such as we've discussed briefly, and leave a gap between the two shells of around 20 cm, I don't think you'll ever know that an airplain flew over if you're inside the studio. (This is, of course, assuming you pay particular attention to your entrance and use a double door, sound lock entrance) Using that wall system, then a 20 cm air/insulation space, then a frame with two layers of 15mm gypsum wallboard, all properly sealed, calculates out to STC 81, with a transmission loss of 42 dB even as low as 50 hZ - a VERY respectable isolation performance for any studio, anywhere. A third layer of wallboard inside would gain you about 3-4 dB in every frequency band. Good choice, my friend - this is the construction of the future, from what I've seen so far... Steve

Steve,I am very happy that my choice is acceptable from you. Its the best choice for my outer shell and I think much lighter that the concrete blocks that I mention earlier. Now my concern is about the stability of my house .I am waiting an enginner to check it. I dont think that I will have a problem,but better to be sure before construction starts. I will do everything you have advice me so far Steve and I am counting on your help and knowledge so my dream comes true. Could I use one of these walls for separating the CR from the studio? Of course with the addition of new walls on both sides. thank you!

"Could I use one of these walls for separating the CR from the studio? Of course with the addition of new walls on both sides." - You could, but depending on materials available in your area you might find it easier to just do double-framed gypsum walls between the CR and other rooms - be careful you don't fall into the trap of too many leaves - 2 leaves and one air space is by far the most efficient use of material. Also, a double-framed gypsum wall would be quite a bit lighter, which may be a consideration for support from below... Steve

Steve,the only reason is that the engineer told me that he HAS to put some walls inside for supporting the roof. I don't like that ,but what can I do? I told him that I will construct new walls inside with my own rules If finally I have to put this wall to CR my thought is M2 in the middle and single frame for each side of the wall which will have 3 layers of drywall all in one side. Mass-spring-mass right?If I wrote it correct! thank you

The M2 wall would be one center of mass - you only want one more, so only one side should get a frame and wallboard, with all layers of wallboard being mounted on the same side of that frame. Fiberglass or rockwool insulation between, and you're set - If you need interior walls for support, it should be the M2 stuff - you can then build the second center of mass as a non-load bearing, isolated wall. In this case, you would need to plan ahead enough to know exactly where your inner walls need to be, since at least part of them will be poured concrete... Steve

Hi Steve, I haven't start anything yet because I have some problems with local laws. I can't do anything over 30-40 tons.The engineer said 40-50 tons...but I just want to be sure for the weight. The M2 is too heavy for my house.About 80 tons for 100 m2. What do you think about their single panel?I don't think it will do the job. What is your suggestion for those perimeter walls?Is the load enought to handle good isolation? thank you!

Yiannis, you can build lighter walls/ceilings with good isolation but it depends on what's available in your area - I didn't see enough information on the single panels on their site to tell what they are doing there, sort of looks like they're just using styrofoam with embedded wire so they can stucco one side?? If so, that would be not too good for sound by itself - under the right curcumstances, though, using that as an outer leaf and multi-layer gypsum for inner leaf could work. 8 foot tall gypsum walls with 3 layers of 15mm will weigh between 65 and 80 pounds per lineal foot, and if you were to use a fairly large air/insulation gap you could still get pretty high sound isolation - the low frequencies would be hardest, that's where the wider air gap would help. Can you give me an idea of the types of materials that are available in your area for outside wall construction? Otherwise, I'm just "flying blind" here... Steve