There are literally millions of homes with cellulose insulation in the attic with installed r values up to r 60 and higher.
Cellulose too heavy attic.
Wear a long sleeved shirt dust mask and.
Settling in attics is less problematic for two reasons.
Patch the holes with tape or canned spray foam see more information on this technique in the article on this page 1.
Second when cellulose insulation in attics settles no empty spaces are formed.
Dry blown cellulose will characteristically settle and sag in place reducing its r value.
When cellulose soaks up moisture in enclosed areas it can take a long time to dry out.
Cellulose is known to create a massive cloud of dust when it is installed meaning breathing apparatus is required if you are considering a large installation.
This should not cause a problem.
Install a continuous layer of rigid polyisocyanurate.
The mounds of loose material fill.
The weight ratio per square foot of 8 1 2 of cellulose is usually 97 pounds per square foot.
Install the fabric and then strap the ceiling with 1x4s or 2x4s.
I would recommend adding an r 40 which would bring you to the maxiumum insulation and the point of diminishing returns on your investment.
As a recycled paper product cellulose is prone to absorb moisture that can cause wood rot and mould.
No one has ever reported a case of a ceiling sagging let alone.
Place a tarp where you plan to collect the cellulose and have large heavy duty trash bags available.
Leave a clear path from the attic to the outside.
Unlike fiberglass insulation installed in roll out batts on the attic floor cellulose is blown into the attic under air pressure through large diameter hoses.
While neither material is listed as a true air barrier meaning it blocks airflow completely cellulose will do a better job at stopping air transfer between the living space below and the attic when you blow in a thick blanket of it.