Roof above rehearsal space, spaced vs. dense planks on roof truss

spitzer

New member
Hi

This is was time-critical so I apologize for possible omissions or vagueness. I'll have more details later... if that even matters at that point.

The flat steel roof above the rehearsal space is being replaced because of thermal insulation problems. Currently the roof structure is just 2x4's, zero insulation (no fiberglass, nothing, just air and a couple of old newspapers) and spaced planks (10 cm distance between them) below the steel. The steel has already been removed so I've seen what's under it. I have no doubt sound is easily going through that kind of structure.

Because I was informed of this only a few days ago, I have had practically no time to react. I have tried to explain to the owner why I'd want this or that to be done -- the attic is accessible only for the very brief time before the new roof is installed, and any soundproofing work would be TRIVIAL and of practically no extra cost from the outside instead of the inside (ceiling side) -- but for some reason the owner is oblivious about it, and doesn't really seem to be listening to my point of view (it'd be so easy to do this now and it costs next to nothing for what could be a huge soundproofing benefit). He did not want me to interfere and thus de facto will not let me work in that space myself. I asked could, at the very least, the support planks under (part of) the new roof be spaced closer together for some extra mass and even that was met with resistance. He thinks the construction company guys "know what they're doing" and I'm sure they do, but a) they are doing thermal insulation b) they are completely unaware of any soundproofing concerns.

In the short time that I had, I nervously looked for info to show the owner that yes, sound going through the ceiling is a problem (and adding mass is part of how that can be reduced). He seemed to think so strongly that it doesn't matter at all, I actually asked him why don't people then have studios with tarp roofs? His answer: a blank, confused stare.

Once the new steel is there, obviously nothing can be done from that side anymore.

What do you think? I can try to provide more detailed info but they might have already installed the new roof before I get a chance... sigh.
 
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Its not clear on the actual structure - you can't use 2x4s to suspend 'planks' or hang a ceiling, they are not strong enough unless it's a tiny area. 2x6 minimum, but 2x8 is better. It sounds like you are concerned with sound getting out?
 
[MENTION=197590]spitzer[/MENTION] - I'll suggest you post some pictures of the space.

Again, it sounds like you are trying sound-proof and that requires several things, including mass, but also de-coupling and sealing. If you don't own the space, but are allowed by the owner, I'd go with sealing (turn off all interior light in the day and look for light or air leakage, attack with silicone/outdoor caulk) and then stuff as much rockwool as you can fit in that 10cm, covering the entire ceiling with acoustic tiles to keep it neat. De-coupling is probably not possible, and unless you're building is underneath a local airport flightpath you and any neighbors will probably be satisfied with the lower sound both in/out through the roof.
 
I'm not allowed (to do sealing or anything at all). The vertical space is more than 10 cm, and will be raised about a further 10 cm higher. I saw the old structure and there were also some fiberglass batts, looked like 30 mm, in there that were not previously visible through the planks (yes, 'planks'. Sort of like in this picture https://dezzoroofing.co.za/wp-content/uploads/2016/09/steel-roof-top-tips-1.jpg . The spacing I was referring to is the spacing between the 'planks' you see in that picture).

My pictures are on my other computer but it doesn't really matter. The owner doesn't even know what the new structure is exactly going to be like. I asked, amongst other things, why can't the planks be placed closer together and turns out, they actually can. But I'm sick and tired of arguing with him. He keeps saying "it'll probably be fine" and keeps referring exclusively to thermal insulation.

The company doing the roof said there's no problem spacing the planks 10 mm apart or 100 mm apart or even without gaps at all.

I would be interested in taking a closer look from a soundproofing (sound reducing) standpoint but I can't. I was informed of this so late I was lucky to even get there in time to see the old stuff being pulled out.
 
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I wouldn't even be concerned about acoustic insulation from the planking, which is there just to provide something for the steel roof to be attached to. Even if they were snug without spacing, it's not going to be much added noise suppression.
Instead, let them do what they will with the roof replacement, and get up into the attic and work the problem there...by adding more insulation on the actual ceiling, from inside the attic...or if you can't do that, just add it inside your room(s) to the ceiling.
 
What's directly under the roof is "the attic". I couldn't care less about the plank spacing -- if it wasn't the only thing I could influence. Honestly, that's the only reason I asked. They agreed to do it denser, hugely denser, which I think would give it more mass and prevent the flat steel from possibly resonating as much. I might be wrong and it might not be much, but I can't do anything else.

Thanks. Goodbye.
 
What's directly under the roof is "the attic".

Right...so can you access the actual attic and add some more insulation to the "top" of your room(s) ceiling...?
What I'm saying is...rather than try to use the steel roof slats as a solution...work it inside the attic on top of your ceiling. If you can't get into the attic, then work the ceiling from inside the rooms.
 
Miroslav,

I can not access the actual attic (well, I can go up there and take a look, but that's it). I was informed of the entire thing less than a week before construction started and there was no time at all to research and design anything from a soundproofing standpoint. I can not add more insulation because I'd need to know what that would be and get special permission to work in that space myself.

I wouldn't want to use the slats as a "solution", I understand what you mean. Personally I'd have done everything possible from the outside, since the ceiling is at about 3 metres and working from that side is very difficult.

Best wishes. Goodbye.
 
Its not clear on the actual structure - you can't use 2x4s to suspend 'planks' or hang a ceiling, they are not strong enough unless it's a tiny area. 2x6 minimum, but 2x8 is better. It sounds like you are concerned with sound getting out?

Mike,

as far as I can tell, the ceiling is just thin (like 5 mm) pieces of board (painted, so not sure what kind). Sounds hollow if you knock on it, from either side. Nailed to the beams from the underside and supported by a grid of thin strips. Its purpose seems to be just to hold the weight of the paper and fiberglass that was above it. The original builder used the cheapest and most random materials possible -- although it all looked to be intact and in good condition considering the age of the building. Obviously not built with soundproofing in mind though.

Best wishes. Bye.
 
The "planks" that carry the roof, tiles, slates etc over here are called Purlins and the normal thermal control that I have seen is to fill the space between the purlins with GF and then clad the outside with plasterboard (sheetrock?). Such a construction is going to damp a steel roof very effectively. Steel is in anycase denser than tile or PB though of course lower in total mass. You cannot (over here and AFAIK) glibly add mass to a roof* unless you get a structural surveyor in to pass it. The owner would of course face considerable extra cost in such a case.

The "sandwich" constuction I mentioned above should be quite effective in reducing noise ingress and egress but of course, not AS effective as more serious methods and sealing. If the work has to pass certain regulations regarding thermal performance they will help with sound proofing. For example, the roof would not insulate very well if a bloody great draught blew through it!

*The roof load pushes the walls out!

Dave.
 
Thanks for your reply.

One "problem" that I have is that I don't know what they intend on doing. I asked the owner how are they going to change the structure, exactly, and he doesn't know either! All I was told that it's going to be raised a little bit higher, presumably to accommodate more insulation while still leaving a sufficient air gap so as to not trap moisture.

I suppose I can just stop worrying about it since there's nothing I can do. They've already started installing the new insulation as far as I know.

Bye
 
Thanks for your reply.

One "problem" that I have is that I don't know what they intend on doing. I asked the owner how are they going to change the structure, exactly, and he doesn't know either! All I was told that it's going to be raised a little bit higher, presumably to accommodate more insulation while still leaving a sufficient air gap so as to not trap moisture.

I suppose I can just stop worrying about it since there's nothing I can do. They've started installing the new insulation as far as I know.

Bye

To be honest and practical? IF they are improving the thermal insulation that is surely going to improve sound proofing anyway? Not the 25dB SPL room you would like but at least you should be warmer!

Dave.
 
To be honest and practical? IF they are improving the thermal insulation that is surely going to improve sound proofing anyway? Not the 25dB SPL room you would like but at least you should be warmer!

Dave.

Heh... usually it's actually too hot in there even in the winter because the heating system is a bit off (it's not distributing the heat evenly). Last month it was over 26 C in there and not much oxygen either. Makes for shorter practice sessions (if you don't die before you get to the door).

It might improve the soundproofing anyway, yes. Probably even. I was just... not happy about many things concerning the project, one being that the soundproofing aspect was ignored and I was given less than 2 days notice (I'm active enough that I and my fellow musicians need to know if we for some reason can't practice!).
 
Heh... usually it's actually too hot in there even in the winter because the heating system is a bit off (it's not distributing the heat evenly). Last month it was over 26 C in there and not much oxygen either. Makes for shorter practice sessions (if you don't die before you get to the door).

It might improve the soundproofing anyway, yes. Probably even. I was just... not happy about many things concerning the project, one being that the soundproofing aspect was ignored and I was given less than 2 days notice (I'm active enough that I and my fellow musicians need to know if we for some reason can't practice!).

Well, YCPAOTPAOTT. Practice in the buff!

Dave.
 
I'd look for a new place to practice! Here in the US that structure with the boards/planks to support the exterior steel roof would not pass code. Neither would your ceiling of 2x4s.
 
Hmm... interesting. I thought the pic in the link from earlier was probably US, although it could be from anywhere really. I haven't pulled the latest pics from my camera yet, so I can't double check and it's quite difficult to explain. The board/plank/purlin structure is for thermal and moisture reasons. There's an attic space with fiberglass or equivalent to keep heat in and a gap above it to allow air to circulate. Otherwise, rot, mold etc. would instantly become a problem. (This is from what I have understood)

This particular building was built in the 60's but it's a standard construction as far as I know. And I was up there observing when they were pulling it out, everything still looked good. No rust and most of the wood was bone dry (honestly, I don't know why they're re-doing it but that's not my concern). I think it was built back in the day by the father of one of the neighbours (master carpenter) and his buddies. Whatever they're doing now probably has to pass the much stricter codes of today.
 
Of course, a new place to practice wouldn't hurt. Probably something bigger...

But this place has its upsides... it's there, it's all set up, it's soundproofed (quite well)... last time I fixed the heating problem by just going to the control room myself and manually dialing it down. Sometimes (actually, most of the time) it's best not to talk to the owner and just do it. In the time it takes him to go through saying "NO!"*, then taking an hour to a day of thinking and then saying "Ok, I see no harm in it so you can try it" I can fix it a billion times.

* his first instinct to everything. He seems to think if I turn a knob on the little control computer, the same thing the "licenced experts" do, I'll burn the house down. Or cause a flood, or cause the car battery to fall out. Something ludicrous anyway.
 
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