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Remodeling an Over Under Duplex. Insulation required between floors?

B

BarryRS

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Joined
May 31, 2024
Messages
1
Location
Charlottesville Virginia
I understand the need for fire separation, two layers of 5/8 drywall etc. I wanted to use safe and sound insulation between floors for sound deadening. Inspector mentioned that "R" rated insulation is required. I don't think that this is in the code, and that the building envelope is the exterior walls, not spaces between heated and cooled occupied spaces.

I would think that the Safe and Sound product with its fire safety characteristics would be a plus.

Anyone have an opinion? Or building code sections that apply and I'm missing?

Thanks!
 
Your inspector makes sense. Go with cathedral R30. Resilient channel for sound,
 
How about "1206.2 Airborne sound. Walls, partitions and floor-ceiling assemblies separating dwelling units and sleeping units from each other or from public or service areas shall have a sound transmission class of not less than 50..."

Put some rockwool in there, it's really not that expensive or hard to add and it will greatly increase the quality of life for the residents. Have you ever lived above or below somebody else where the floor-ceiling assembly wasn't insulated? It really sucks. This is the time to do it and it should be done. IMHO.
 
BarryRS said:
I understand the need for fire separation, two layers of 5/8 drywall etc. I wanted to use safe and sound insulation between floors for sound deadening. Inspector mentioned that "R" rated insulation is required. I don't think that this is in the code, and that the building envelope is the exterior walls, not spaces between heated and cooled occupied spaces.

I would think that the Safe and Sound product with its fire safety characteristics would be a plus.

Anyone have an opinion? Or building code sections that apply and I'm missing?

Thanks!
Click to expand...

Ask the inspector to cite the code section he's relying on. I don't think he has one. Unless California has some [more] special rules, thermal insulation is only required in the thermal envelope of the building, not between individual units or spaces that are entirely within the thermal envelope.

Safe-N-Sound is mineral wool. It offers thermal insulation as well as sound deadening, although probably not as good as fiberglass. Did he happen to mention what R-value he thinks is required? Mineral wool may meet that.
 
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