The question is how to add mass to the outer leaf of my existing wall structure. I have started a bedroom remodel, intending to improve the soundproofing. The walls 8 feet high, framed in 2x6, and the exterior sheating is black asphalt construction board, the exterior siding is a wood siding. Anyway, I have to add the mass inside the wall between the studs. I was pretty careful tearing out the drywall, I have a lot of pieces that can be trimmed and glued to the construction board. I suppose I could buy new drywall, or some type of MDF, and cut pieces to fit between the studs. I'm a little cautious using the MDF or fiberboard inside the wall. Homasote is too expensive. The wall will eventually be insulated with rockwool and finished inside with RC and layers of drywall etc.
Anyway, any good suggestions ?
Adding Mass to existing wall structure
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knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
If your vapor barrier is still intact you can just add a couple of layers of wallboard between studs, sealing with acoustic caulk as you go - I'm not sure which is better in this case, edge gluing or complete lamination at that point - I only know that they will act differently.
If you only glue at the edges, you leave the layer free to act at it's own resonant frequency, which will be different than the outer wall sheath - this is good, in that each layer will have its own, different, coincidence dip so no one frequency will pass through easily.
If you completely laminate (100% glue coverage) the added inner layers, you make it effectively one panel and LOWER the resonant frequency - this can help stiffness and improve low freq Tranmission Loss, but gives only a SINGLE coincidence dip. (for that leaf of the wall, that is)
If you use RC on the inside with two different thicknesses of wallboard, that will give two different coincidence dips, and with a solid outer leaf you'd have three, you should get good TL overall, with possibly BETTER low freq performance. The outer, stiffer leaf handles LF and the inner, flexible, multi-layer (but NOT laminated) multi-layer leaf handles the rest.
There are a few wall threads in the construction forum where I explain mounting for different wall constructions, you should brouse those also... Steve
If you only glue at the edges, you leave the layer free to act at it's own resonant frequency, which will be different than the outer wall sheath - this is good, in that each layer will have its own, different, coincidence dip so no one frequency will pass through easily.
If you completely laminate (100% glue coverage) the added inner layers, you make it effectively one panel and LOWER the resonant frequency - this can help stiffness and improve low freq Tranmission Loss, but gives only a SINGLE coincidence dip. (for that leaf of the wall, that is)
If you use RC on the inside with two different thicknesses of wallboard, that will give two different coincidence dips, and with a solid outer leaf you'd have three, you should get good TL overall, with possibly BETTER low freq performance. The outer, stiffer leaf handles LF and the inner, flexible, multi-layer (but NOT laminated) multi-layer leaf handles the rest.
There are a few wall threads in the construction forum where I explain mounting for different wall constructions, you should brouse those also... Steve
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...
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egcc
- Posts: 23
- Joined: Tue Mar 25, 2003 7:08 am
Thanks. I'm basically just gluing a couple layers of drywall between each stud. Will have a new vapor inhibitor in place when the new insulation is added. unfortunately I picked the hottest couple weeks of the year to do this project. Temperatures in the 100s expected for another week or two. Anyway, thanks again.
Eric
Eric
EGC