First of all: great forum! I've learned a lot here and I'm about to start construction of a new studio, so the expertise found here has for sure changed a lot of my ideas for how to build it.
I have a simple question though (which probably isn't easy at all to answer in the end I guess). For the live room, my plan is to build a wall with two layers: one layer of fiberboard and one layer of plasterboard on top. Probably the same goes for the ceiling. What I wonder is, should I glue the two layers together, or should I leave them like they are?
As far as I've understood, the boards will resonate at different frequencies and my idea is that if I don't glue them I should get a better STC rating. On the other hand, if I glue the two, the mass will be higher, which might give me an even higher STC. So which is correct?
Also, if gluing is preferred, would it still make sense to go for the fiberboard or would I get about the same result with double plasterboard? Plasterboard is generally cheaper and going for only that might mean that I could get three layers instead.
Fiberboard and plasterboard: should I glue?
Originally posted at johnlsayers.com, topic 9777.
1) DO not glue them together - no - it won't increase your mass (the mass will remain the same - just one piece instead of 2) - also - it will decreease your LF isolation. 2) The fiberboard is a waste of money - the greater mass of the drywall will increase your isolation tremendously. If you are not using isolated construction - then you will be much better suited with installing RC-1 and 2 layers than you would with fiberboard and 2 layers. If you are adding a wall inside of your wall - then the RC is nott necessary. JUst use the drywall - If you are going to consider a 3rd layer of drywall - I would suggest green glue instead - the total cost will be ablout the same as the drywall (if you include labor) but the bang for the buxck will be almost equiviloent to 4 layers of drywall. RodI have a simple question though (which probably isn't easy at all to answer in the end I guess). For the live room, my plan is to build a wall with two layers: one layer of fiberboard and one layer of plasterboard on top. Probably the same goes for the ceiling. What I wonder is, should I glue the two layers together, or should I leave them like they are? As far as I've understood, the boards will resonate at different frequencies and my idea is that if I don't glue them I should get a better STC rating. On the other hand, if I glue the two, the mass will be higher, which might give me an even higher STC. So which is correct? Also, if gluing is preferred, would it still make sense to go for the fiberboard or would I get about the same result with double plasterboard? Plasterboard is generally cheaper and going for only that might mean that I could get three layers instead.
Thanks for the tips, Rod!
First of all, RC=resilient channel? If so, that's exactly what I was planning to go for, so I guess I'm on the right track.
Not sure what you mean with isolated construction; we are building middle walls inside a large open area. These walls will be separated about a foot from the current walls and the rooms will have their own ceilings which will also be about a foot below the current, so the rooms will be "free" from the rest of the building apart from the floor. I was considering making a floating floor but I found this theory here on the board that it's not necessary, and since it will all be built in the bottom floor on thick concrete with nothing underneath, I want to try if this theory will work!
So does this mean it is isolated? And if so, will I LOSE anything on working with resilient channel? It will not add so much to the costs I guess but if it doesn't make any difference I could just skip it.
So, two layers of drywall, that will certainly make the construction cheaper and I'll look into adding a third layer too in that case. I guess the biggest cost is for the insulation anyway so "small" changes like that will be marginal in comparison.
Yes that is what it means - and no you are not on the right track.First of all, RC=resilient channel? If so, that's exactly what I was planning to go for, so I guess I'm on the right track.
You already have isolated construction - and adding the RC will loose Tl value - not gain it . Yup =- it punishes you if you don't need it......... The reason is this - with one wall - you are installiong a flimsy material that becomes a point of decoupling from the physical stud frame..... so you gain a lot (about 6 dB) just from loosing the impact transfer that takes place through the wall frames........ BUT - once you decouple the walls themselves (build 2 seperate walls not touching one another anywhere) and especially when you add a completely separate ceiling - you already gained the advantage of not having the impact transfer from one wall face to the other - and are getting a penalty because of the floopy RC frame rather than installing the drywall directly onto the more rigid studs. For the same reason - you get better Low Frequency isolation by using 2x6 @ 24:" o.c. than you will using 2x4 @ 16" o.c. It's exactly the same board feet of lumber to build either wall - but the 2x6 wall is slightly more rigid - and will therefor increase your low frequency isolation. The stiffer the better....... the more raw mass the better......Not sure what you mean with isolated construction; we are building middle walls inside a large open area. These walls will be separated about a foot from the current walls and the rooms will have their own ceilings which will also be about a foot below the current, so the rooms will be "free" from the rest of the building apart from the floor. I was considering making a floating floor but I found this theory here on the board that it's not necessary, and since it will all be built in the bottom floor on thick concrete with nothing underneath, I want to try if this theory will work! So does this mean it is isolated? And if so, will I LOSE anything on working with resilient channel? It will not add so much to the costs I guess but if it doesn't make any difference I could just skip it.
if the biggest cost is in the insulation in the wall - you are using the wrong insulation big time - that should be your least expense - all you need is fluffy insulation to fill the cavities with........ RodI guess the biggest cost is for the insulation anyway so "small" changes like that will be marginal in comparison.
Well I'm CERTAINLY glad that I started asking these things before I have started building or buying material! So ok, the RC is history, I'll scrap that from the list of ideas for sure. Another question: we are planning on working with a metal stud frame. But now I'm starting to think that it's maybe the totally wrong thing to do, since they have way less mass and will basically work kind of like an RC in the end. Is this correct? And if we still go for the metal studs (we can get some of it basically for free and overall it's cheaper and easier to work with), how much would we lose because of it?You already have isolated construction - and adding the RC will loose Tl value - not gain it .
This is quite the opposite of what I've thought so far. My idea is to use high-density mineral wool, which is not exactly cheap. But what you're saying is that I could go for lower density wool (waaaay cheaper) with the same or even better result?if the biggest cost is in the insulation in the wall - you are using the wrong insulation big time - that should be your least expense - all you need is fluffy insulation to fill the cavities with........
PLease review IR-761 - compare double stud wood walls to double stud steel framing - making sure that the 2 walls are identical in every other respect. You can then compare the walls TL values side by each.Another question: we are planning on working with a metal stud frame. But now I'm starting to think that it's maybe the totally wrong thing to do, since they have way less mass and will basically work kind of like an RC in the end. Is this correct? And if we still go for the metal studs (we can get some of it basically for free and overall it's cheaper and easier to work with), how much would we lose because of it?
Unless fluffy fiberglass is more expensive where you are located than lower density rockwool - just use the fluffy insulation - otherwise use the cheapest rockwool you can buy. Sincerely, RodThis is quite the opposite of what I've thought so far. My idea is to use high-density mineral wool, which is not exactly cheap. But what you're saying is that I could go for lower density wool (waaaay cheaper) with the same or even better result?