I'm following Rod Gervais' excellent book on designing studios, although I'm doing a home theater in a basement.
I'm about to place a dual layer of gypsum boards between the joists as described in figure 4.19. That's all well, but then I thought about the "side wall" above the concrete wall (see figure). Isn't this a weak spot when thinking sound insulation? An inch or two of wood compared to the 25 cm concrete wall?
I'm very sorry that I cannot describe this part of the house construction better, but i don't even know what it's called in my own language... :oops: And I don't know if this is a construction detail that is know outside of Norway for that matter...
What I'm wondering about is if I should cover these parts with a dual layer of gypsum too. Is it going to make any difference? For the better? For the worse?
I hope the image clarifies my question, and please ask me if I haven't been clear enough.
Please help me with a wall construction detail
Originally posted at johnlsayers.com, topic 9999.
Rune W
Yes it is a weak spot in terms of mass. In all case make sure it is sealed But your question all depends on the goal your trying to achieve. Is it important that the sound is not disturbing the sourroundings of the house ? Or are you just trying to keep the sound from escaping your home theatre thru the other rooms of your house. What are the "normal condition" of listening in that room, is it very loud ? if it,s not maybe you can just leave it like that. If you go for it, just make sure you put the GB direcly on the wood joist, do not create a situation where you would make another air space between your newly instaled GB and the wood joist.
With the info i have this is my answer, hope it helps.
regards
Hi orangenumerik, and thanks for your reply!
Both, I guess, but in this particular case I was thinking of sparing my neighbours.But your question all depends on the goal your trying to achieve. Is it important that the sound is not disturbing the sourroundings of the house ? Or are you just trying to keep the sound from escaping your home theatre thru the other rooms of your house?
The normal condition will not be that loud, but sometimes I really like to play loud when watching movies, and I happen to like LFE...What are the "normal condition" of listening in that room, is it very loud ? if it,s not maybe you can just leave it like that.
Yes, thanks a lot. Now I know that at least I haven't done anything wrong. I didn't hear anything here, so I went ahead and put 1 layer on the wall + 1 layer on the ceiling + 1 layer on the wall (all caulked between) and the result look like this:If you go for it, just make sure you put the GB direcly on the wood joist, do not create a situation where you would make another air space between your newly instaled GB and the wood joist. With the info i have this is my answer, hope it helps.
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Rune, that's good......... but you already had that info in the book (I had to check to make certain I hadn't screwed up and missed it That would have been bad........ :oops: ) It's detailed in Figure 10.9 on page 240. BTW - You did a nice job on it - are you adding more layers? Sincerely, RodYes, thanks a lot. Now I know that at least I haven't done anything wrong. I didn't hear anything here, so I went ahead and put 1 layer on the wall + 1 layer on the ceiling + 1 layer on the wall (all caulked between) and the result look like this:
What? I must have been sleeping through class... :oops: I'll look it up when I get home (not that I need to now).Rune, that's good......... but you already had that info in the book (I had to check to make certain I hadn't screwed up and missed it That would have been bad........ :oops: ) It's detailed in Figure 10.9 on page 240.
No, I don't think so. The carpenters actually came when they said they should... Doesn't happen too often around here. So I'm fairly pressed for time. I'm sorry to report that I've only got time for one layer of gypsum in the ceiling (between the joists up against the floor). This will be caulked good, so at least the layer is going to be "airtight". I don't remember now, if the double layer of gypsum had any more functions than making the "floor layer" heavier and airtight. I'm thinking that my floor is fairly heavy already, so maybe it's not a total disaster even with only one layer of gypsum below. Due to a miscalculation by some carpenters when adding a section to my house, the floor had to be elevated around 25 mm to match the height of the existing floor. So in addition to the floor decking I have: - 4 mm "step sound" board (sorry I have no clue what it's called in English) - 4 mm "step sound" board - 19 mm particle board - parquet underlay - parquet (see figure below and try to ignore the Norwegian words) So my floor is at least a little bit heavier than "normal". Maybe it makes up for one missing layer of gypsum below...BTW - You did a nice job on it - are you adding more layers? Sincerely, Rod
Rune,
that does look pretty good.
Question for you - how are you beacing the bottoms of your floor joist so that they cannot roll under loading?
Rod
I've been thinking about this. Seems like it is more common in the States to use "wood" between the joists (for "normal" floors) than i Norway. I don't know if this is because we are using a little larger joist dimensions or what. It's the carpenters that has calculated the 2x8's for me. I guess he's not concerned that they are going to roll. The span width is about 4 meters. If you're concerned that they might roll with 3 layers of gypsum, I might have to figure something out. I'm thinking triangular wood pieces like shown below (that is fastened through the gypsum layers). Not the best of solutions, for sure, but maybe better than nothing?Rune, that does look pretty good. Question for you - how are you beacing the bottoms of your floor joist so that they cannot roll under loading? Rod
Sorry I misunderstood. You were talking about the bottom of the floor joists - not the other way around. Well, maybe the same solution, only mirrored, would apply
Actually - the code calls for mid span bracing whenever the joist length exceeds 8' - so it would be both the ceiling joist and the floor joist. But I see it now - the angled braces (triangular shaped) bracing the top os the ceiling joist - Yes - do that there - and reverse them for the floor joist - That's a cute trick - I am going to have to bemember that. RodSorry I misunderstood. You were talking about the bottom of the floor joists - not the other way around. Well, maybe the same solution, only mirrored, would apply
Another thing, Rod, while I remember it. Do you think the rockwool thickness (200 mm) is ok? There will be about 4 cm or so of air on the top (as pictured above).
RuneW -
This setup you have with side bracing -
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Is exactly what I did with the independantly framed ceiling of my basement thread.
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8887&start=30
The following is how I did the same thing on the edges or where the ceiling joists rest on the two frames. (other side is a double header wall). I have larger triangles in the middle of the span, but this was the idea.
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I had a tight or small clearance between the top of the ceiling and the bottom of the floor joists. I pre-cut and drilled for screws to fasten to the ceiling joist spans. It's at the midpoint of the ceiling span which is 9', so I estimated that it would do the trick for keeping the ceiling joists from kicking or bending.Rune - that should be fine - actually - you would have been a little better off wiuth fluffy insulation - but this will do ok as well. RodAnother thing, Rod, while I remember it. Do you think the rockwool thickness (200 mm) is ok? There will be about 4 cm or so of air on the top (as pictured above).
Thanks, Cram, it's nice to see that it has actually been done :)RuneW - This setup you have with side bracing - Is exactly what I did with the independantly framed ceiling of my basement thread.
Difficult question, but how "fluffy" do you mean? The Rockwool I'm using (it's standard house insulation) seems quite "fluffy" to me. Fluffy enough to make it impossible to stack in a fast and careless way, at least... :wink:Rune - that should be fine - actually - you would have been a little better off wiuth fluffy insulation - but this will do ok as well. RodAnother thing, Rod, while I remember it. Do you think the rockwool thickness (200 mm) is ok? There will be about 4 cm or so of air on the top (as pictured above).
Rune, By fluffy I was refering to fiberglass insulation - roughly 1.2 pcf. which is widely available here in the US and is typically used as standard building insulation. It may not be either readily available - or could even be more expensive - than the rockwool you're using (which here in the states we would pay a premium to install). Don't worry about it - it will be fine. RodDifficult question, but how "fluffy" do you mean? The Rockwool I'm using (it's standard house insulation) seems quite "fluffy" to me. Fluffy enough to make it impossible to stack in a fast and careless way, at least... :wink:
Obviously there is no such code here in Norway, because I've been in contact with a few structural engineers (and carpenters) and nobody see the need for such a bracing. But then again, I'm fairly sure that none of the guys I've been speaking to has built a studio or home theater... So, I guess the question is this: Will it affect the sound insulation in any way (because this is my #1 priority with this project)? BTW, here is the double joists in place:Actually - the code calls for mid span bracing whenever the joist length exceeds 8' - so it would be both the ceiling joist and the floor joist. But I see it now - the angled braces (triangular shaped) bracing the top os the ceiling joist - Yes - do that there - and reverse them for the floor joist - That's a cute trick - I am going to have to bemember that. Rod
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(Larger photo here)
One thing I forgot to mention before. In a moment of madness(?) earlier, I tried to reinforce the floor joists by glueing/screwing 244x23 cm strips of plywood centered on each floor joist (se pic above). I guess my hope was to lessen the need for bracing this way... :oops:The requirement here has nothing to do with the type of use for the building - it is the same for all buildings. If it isn't a code issue where you are - don't worry about it....... RodObviously there is no such code here in Norway, because I've been in contact with a few structural engineers (and carpenters) and nobody see the need for such a bracing. But then again, I'm fairly sure that none of the guys I've been speaking to has built a studio or home theater...