. Both are better; depending upon who you listen to. I built a place in '98; two major concerns of mine were energy efficiency and minimizing environmental impact. Cellulose wins both, hands down in my opinion. Wive's tale #1 about c'lose . . it has less insulating ability when it's settled. True; however the R-value is based upon SETTLED density . . so you get some "extra" R-value at installation which fades over time to the rated value. If you use wet-blown, no settling occurs. Wive's tale #2 about c'lose . . it loses it's fire retardancy with time. Horseradish ! I took a sample from a friends house over 20 years old . . could NOT get it to burn in direct propane torch flame. Nor could I get a brand new sample to burn. Wive's tale #3 about c'lose . . fire retardant is a dangerous chemical. Bolderdash ! Borate salts . . . not terribly far from the stuff used in Borax ( hence it's name ) and also very similar to boric acid used to treat eye infections. While it's not Kool-aid or seasoning; it's certainly not a dangerous chemical unless you purposely ingest the stuff. It's also a good sound deadener; it was in fact originally developed FOR that purpose. The very fact that it has a tendancy to settle; is part of what makes it such good insulation . . . tends to move / fill any little gaps etc that occur when the place moves / shrinks / swells throughout the seasons. I also liked the fact that the embodied energy ( energy used to MAKE the stuff ) is incredibly low when compared to f'glass which takes LOTS of energy to make. No outgassing or "itchies" from cellulose, either. Plus; f'glass will NEVER degrade . . . cellulose eventually will if left to the elements . . . Perfect stuff for an attic . . . just blow it in, but make SURE you have adequate ventilation up there . . . that applies for ANY insulation . . . . I'd choose it simply because it's better insulation from any standpoint I know of . . . the fact that in your case it's cheaper is just a bonus . . . There's my 2 cents . . Bob

Solargary, thank you so much for your reply. Very helpful. I did not know that DIY blow insulation is that easy.... My house is about 1400 sq, and where I can stand is almost on the left edge. Do you think that the blow machine still can shoot out the insulation that far (about 35 feet away)?

The most economical method is lay bats on top of what's there. You can also use "Pour in insulation" in bags and just dump it. No need to crawl all over,use a garden rake to push/pull it where it's needed.

The paper is the moisture barrier and needs to be on the towards the conditioned (interior) side of the house or garage. This is done to prevent moisture from getting into the insulation and ruining it. You can't put something above the insulation that would trap moisture. If the joists are above or close to the level of the height of the insulation, then the best option would be to lay sheets of plywood on top of the joists. This would give you a place to stand and store items. If you have blown in insulation you could clear an area and give up some R value. If you have fiberglass batts that are too high, then you could compress them and also give up some R value. If the batts are too high, then you could remove a section and replace it with a less thick batt in the that area.