Combining dense pack cellulose and mineral wool in double-stud wall
I’m planning to build a double stud wall around 10″ thick. My initial plan was to use dense pack cellulose with an interior smart vapor retarder (intello +).
For a few reasons I am considering adding some mineral wool to the equation. I wanted to bounce the idea off others and see if it make sense.
1) This is for a wood shop and potential music studio (combined) so reducing noise escape is very important. I am aware that air leaks are vital for sound containment, but I have also heard great things about mineral wool. Would there be a discernible difference between 3.5″ of mineral wool coupled with dense pack vs just 10″ of dense pack?
2) I am planning on dense packing myself and am concerned about having 10″ deep cavities as far as difficulty of controlling density (not experienced with it). I also am not sure that there are many professional folks around me experienced with it either.
3) I would prefer not to have walls deeper than 10″ and the mineral wool would add some R-value for the given depth
4) If I do use mineral wool, is there an ideal location for it in the assembly. My initial idea was, from the exterior sheathing in: DP cellulose, insulweb on backside of interior studs, mineral wool, intello (or membrane could be used in this case), 2×2 service cavity battens, drywall. Then I thought perhaps it’d be best against the sheathing in between the exterior studs, followed by dp cellulose. I am tempted by an integrated service cavity approach, but worry that with only a 10″ wall, the vapor retarder needs to be all the way to the inside to follow the 1/3 to 2/3 insulation rule.
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