What's the Best Sandwich?

[mark_g]

We're about to sheetrock--new construction hi-end residential, wood framing 16 & 24" oc.

Want to do two layers of ½" board on each side of partition walls and on ceilings, with Green Glue in between to segregate the quiet rooms (bedrooms) from the rest of the house.

Question--would using Wonderboard, or Soundboard offer any benefit over std wallboard/drywall as the first layer? I've read that greater mass = greater sound absorption. Wonderboard is almost two times heaver than std sheetrock. Also heard that mixing materials can have a cumulative/additive (positive) effect.

Not sure if that would be true on the ceilings--not looking to reduce impact noise, just airborne noise.

Negatives are difficulty installing, and the panels are smaller, so there wd be more joints. Still, we will go over the first layer with good quality gypbd and plenty of GG in between.

Thanks for feedback, Mark

 

[jeffsg4mac]

Oh I was going to say a pressed cuban, Fench Dip or Ruben. Never mind!

 

[Rickster71]

I would've used six inch plates while framing, and then use 2x4 studs; the studs would be offset to isolate the two walls.
See this link: http://www.your-home-theater-design.com/noise-control.html

Greater mass and decoupling are the way to go.

 

[mperfct]

I used double 5/8'ths rock with GG, and have been very happy with the results. I think that as long as you take care of HVAC and electrical outlets (to a lesser degree), that it is a very good sound isolation technique. You are going to be getting diminished returns by swapping in more expensive rock, imho. Although, if you have the budget, knock yourself out.

 

[Rod Gervais]

I used double 5/8'ths rock with GG, and have been very happy with the results. I think that as long as you take care of HVAC and electrical outlets (to a lesser degree), that it is a very good sound isolation technique.

I would have to agree, the added drywall mass is quite meaningful (more than a 25% increase in mass if you use 5/8" Type X Gypsum board) for very little added investment (strictly material costs and a slight additional labor cost - taping is the same regardless)

You are going to be getting diminished returns by swapping in more expensive rock, imho. Although, if you have the budget, knock yourself out.

This may or may not be true......

I always recommend using tested assemblies if you really want to know your walls are going to work.

Low frequency transmission are controlled by both the mass and stiffness of the wall assembly... stiffer wall panels actually lower the TL Values of walls - which is one of the reasons you get a boost in LF TL values by installing 2x6 framing on 24" centers over 2x4 framing on 16" centers.

The panel face is not as stiff in the 2x6 wall (even though the stud itself is much stiffer) and with exactly the same amount of mass - you get an increase in isolation where it counts (high frequencies are easily dealt with in either case).

Rod Gervais
Director of Education
GIK Acoustics

 

[mtrycrafts]

We're about to sheetrock--new construction hi-end residential, wood framing 16 & 24" oc.

Want to do two layers of ½" board on each side of partition walls and on ceilings, with Green Glue in between to segregate the quiet rooms (bedrooms) from the rest of the house.

Question--would using Wonderboard, or Soundboard offer any benefit over std wallboard/drywall as the first layer? I've read that greater mass = greater sound absorption. Wonderboard is almost two times heaver than std sheetrock. Also heard that mixing materials can have a cumulative/additive (positive) effect.

Not sure if that would be true on the ceilings--not looking to reduce impact noise, just airborne noise.

Negatives are difficulty installing, and the panels are smaller, so there wd be more joints. Still, we will go over the first layer with good quality gypbd and plenty of GG in between.

Thanks for feedback, Mark

If you end up doing two layers of drywall, I would use two different thickness for each layer. I read in the past that the two different masses have a better effect on controlling sound isolation.

 

[mtrycrafts]

I would've used six inch plates while framing, and then use 2x4 studs; the studs would be offset to isolate the two walls.
See this link: http://www.your-home-theater-design.com/noise-control.html

Greater mass and decoupling are the way to go.

I used that in my outside walls when I built the home in my link.
Boy, is it ever quiet and energy efficient.

 

[Rod Gervais]

If you end up doing two layers of drywall, I would use two different thickness for each layer. I read in the past that the two different masses have a better effect on controlling sound isolation.

Actually you are much better off with the added mass. There really is no benefit with this approach.

The added mass grants you greater isolation in lower frequencies.

Sheets of different thicknesses (thus mass) provide a slight benefit in the panel's coincidence frequency range....... which is higher in frequency and always has a much greater level of isolation to begin with.

The slight decrease of the dip that exists in the coincidence region using different thickness sheets (which will still occur - only to a slightly lesser extent) is really no gain when compared to the loss in low frequency TL values, which is the frequency range that really matters the most.



That really is a losing proposition - regardless of what you may have heard.

Rod Gervais
Director of Education
GIK Acoustics

 

[mtrycrafts]

Actually you are much better off with the added mass. There really is no benefit with this approach.

The added mass grants you greater isolation in lower frequencies.

Sheets of different thicknesses (thus mass) provide a slight benefit in the panel's coincidence frequency range....... which is higher in frequency and always has a much greater level of isolation to begin with.

The slight decrease of the dip that exists in the coincidence region using different thickness sheets (which will still occur - only to a slightly lesser extent) is really no gain when compared to the loss in low frequency TL values, which is the frequency range that really matters the most.



That really is a losing proposition - regardless of what you may have heard.

Rod Gervais
Director of Education
GIK Acoustics

OK, I will erase those thoughts