Ceiling Insulation

[geecast]

Hello,

I would like to improve isolation between floors in my building. The control room is located on the second floor, and live room is on the ground floor. Building construction is brick/cinder block with I-beams and 2x10's supporting the second floor. Currently there is no insulation between the floorboards and the ceiling. My plan is to remove the existing ceiling, insulate, attach resilient strips and 5/8" drywall.

Does ceiling insulation need to be pushed-up right against the floor, or should there be an air space in between the floor and the insulation?

I've got about 10 inches of space to work with, and I was thinking of using Roxul's Safe n Sound.

Thanks,

Gilles

[Soundman2020]

Hi Gilles, and welcome!!!

Building construction is brick/cinder block with I-beams and 2x10's supporting the second floor.

What is the second floor itself made of? Wood? Concrete? Tile? Something else? That's important. If there isn't much mass up there, you might need to "beef it up". But you will need to seal it, very carefully. No air gaps!

My plan is to remove the existing ceiling, insulate, attach resilient strips and 5/8" drywall.

Right. But do make sure you get proper Resilient Channel: Hat channel looks similar, but does nothing acoustically. Or use hat channel plus isolation clips.

Does ceiling insulation need to be pushed-up right against the floor, or should there be an air space in between the floor and the insulation?

Fill that cavity with as much insulation as you can afford (all 10" if you can!). Use density of around 50 kg/m3 if you use mineral wool, or around 30 kg/m3 if you use fiberglass. If you can't afford to fill the cavity completely, then as long as you have at least 4" (10cm) in there, you should be good. Just be careful to not pack it in too tight: if you fill it full, use only enough to just fit in: don't compress it or force it in.

I've got about 10 inches of space to work with, and I was thinking of using Roxul's Safe n Sound.

That will work just fine.

But what type of problems are you having right now? Is it impact noises that are bother you( people upstairs walking on the floor, and being heard down below)? Or is it airborne transmission going the other way (loud sounds downstairs bleed through into the room above)?


- Stuart -

[geecast]

Hey Stuart,

What is the second floor itself made of? Wood? Concrete? Tile? Something else? That's important. If there isn't much mass up there, you might need to "beef it up". But you will need to seal it, very carefully. No air gaps!

The second floor is made of wood. Approximately 6 inch wide planks, then plywood subfloor, and tiles.

Right. But do make sure you get proper Resilient Channel: Hat channel looks similar, but does nothing acoustically. Or use hat channel plus isolation clips.

What kind of resilient channel would you recommend? Would something like Auralex's RC-8 Resilient Channel do the trick?

But what type of problems are you having right now? Is it impact noises that are bother you( people upstairs walking on the floor, and being heard down below)? Or is it airborne transmission going the other way (loud sounds downstairs bleed through into the room above)?

I need to do both. The control room is on the second floor, and live room is on the ground floor. So I need to minimize impact noises from above, as well as transmission from the live room to the control room.

Thanks,

Gilles

[Soundman2020]

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The second floor is made of wood. Approximately 6 inch wide planks, then plywood subfloor, and tiles. 

That's good news! You have some reasonable mass up there, with those tiles and wood.

What kind of resilient channel would you recommend? Would something like Auralex's RC-8 Resilient Channel do the trick?

Should work fine. The reason I made that comment is because some folks occasionally confuse ordinary hat channel for resilient channel.

I need to do both. The control room is on the second floor, and live room is on the ground floor. So I need to minimize impact noises from above, as well as transmission from the live room to the control room.

With tile on the upper floor, about the only thing you can do to reduce impact noise is to use throw rugs in places where impact might occur. However, that might change the acoustics of the control room...

So your basic plan is fine: as long as the cracks between those 6" planks are sealed well, and the new ceiling has enough mass on it, and there is substantial insulation in that cavity, then you should get a good increase in isolation.


- Stuart -

[treatments]

There is a 1 1/2" space between the floor joists that run along each side of the building and the cinder block walls. I believe it is because the electrical conduits, as well as hot water pipes run along the side of the walls.

Should I stuff it with the same insulation I will be using in the rest of the ceiling(Roxul Safe n' Sound) , or is there another product that would be better for this situation.

Thanks,

Gilles