Rockwool Installation in Ceiling

[kinggsxr]

I'm having my basement finished and decided to add Rockwool Safe n Sound in the ceiling and interior walls for added noise reduction.

Contractor went to install it today and realized my joist spacing is non-standard and is varying between 18" and 19" OC (engineered wood joists).

Instead of swapping out with 24" batts and having a lot of waste he came up with a workaround which was to use 1/4" ply straps on the flange of the joists and use it as support along with a 3" strip of Rockwool to fill the rest of the space.

I'm left wondering if this is an acceptable solution to the problem and if this installation method is ok for the basement.

For anyone who has installed Rockwool or had it done in their basement, does this look legit?

 

[mike93lx]

Looks well done to me

 

[sherlocktk]

I ran into a similar issue where by 24'' on center studs were like 24.5 on center, nothing would hold up. I Did something similar by wedging small slivers on one side, and it has not moved in 7 years. I do not have any "supports" underneath it the friction fit was and still is just fine.

 

[kinggsxr]

Maybe I was overthinking it. I was just worried it was a janky fix but I should give the guy some credit.

I also wondered if I was losing performance on the sound damping with the 9" air gap in each cavity, but I can't justify tripling the amount to fill each cavity or going with thick R-30 stuff.

 

[racecougar]

I'd say he's going above and beyond what he likely bid. He absolutely deserves credit.

 

[Hohn]

I'm having my basement finished and decided to add Rockwool Safe n Sound in the ceiling and interior walls for added noise reduction.

Contractor went to install it today and realized my joist spacing is non-standard and is varying between 18" and 19" OC (engineered wood joists).

Instead of swapping out with 24" batts and having a lot of waste he came up with a workaround which was to use 1/4" ply straps on the flange of the joists and use it as support along with a 3" strip of Rockwool to fill the rest of the space.

I'm left wondering if this is an acceptable solution to the problem and if this installation method is ok for the basement.

For anyone who has installed Rockwool or had it done in their basement, does this look legit?

looks great to me. Doing the Roxul when we finished our basement was one of the best decisions I made.

 

[egdede]

Well, I;ll be the GJ voice of doom: Is there an air gap on the side when the spacing goes big? If so you will have sound air leaks (which means sound suppression and insulation effectiveness will be compromised) I turned mine sidesways, and cut out pieces block by block where I had wide-spaced joists. A bit extra work, biut probably less than the added 'strapping'.

 

[racecougar]

Well, I;ll be the GJ voice of doom: Is there an air gap on the side when the spacing goes big? If so you will have sound air leaks (which means sound suppression and insulation effectiveness will be compromised) I turned mine sidesways, and cut out pieces block by block where I had wide-spaced joists. A bit extra work, biut probably less than the added 'strapping'.

Per the OP, and the photos, it's filled:

Instead of swapping out with 24" batts and having a lot of waste he came up with a workaround which was to use 1/4" ply straps on the flange of the joists and use it as support along with a 3" strip of Rockwool to fill the rest of the space.

 

[HogDude]

Well, I;ll be the GJ voice of doom: Is there an air gap on the side when the spacing goes big? If so you will have sound air leaks (which means sound suppression and insulation effectiveness will be compromised) I turned mine sidesways, and cut out pieces block by block where I had wide-spaced joists. A bit extra work, biut probably less than the added 'strapping'.

Love your Snyder pic too!

 

[kinggsxr]

Thanks for the feedback. I know that this will not magically eliminate all noise from upstairs but if it's enough to limit it a bit I think it's worth it.

I have 3 little ones under 3 years old running around constantly and I know it won't do anything to eliminate the sound transfer from the floor above via the joists but I really did not want to do down the rabbit hole (and money pit) of complete sound isolation.

 

[egdede]

And I did read the post, must not have had my coffee yet... Snyder picture?

 

[CombatNinja]

That is 100% the correct way to do that in this case. Go worry about something else now.