The aluminum foil in a package containing 75 square feet of foil weighs 12 ouncesAluminum has a density of 2.70 g/cm^3
I WOULD BE IN FAVOR OF BATS WITH ALUMFOIL BECAUSE OF THE REFLECTIVE PROPERTIESI BELIEVE THAT WOULD ADD THE RADIANT BARRIER FOR A SIGNIFICANT IMPROVEMENT IN THE SUMMER HEAT LIKE I HAVE IN HOUSTON THE BLOWER WITH CELLULOSE IS GOOD AND LOTS EASIER WHERE THE ROOF IS LOW PITCH AND BATS ARE TOO HARD TO INSTALL SO IT DEPENDS ON THE SITUATIONIN SOME CASES EVEN A COMBINATION OF BOTH WOULD BE IN ORDERI SURE DO LIKE THE IDEA OF HAVING THE RADIANT BARRIER.
I currently added fiberglass bates on top of mine old insulationIt turns out really goodBut if you decide to do it make sure you have a good breathing maskAlso don't climb in the attic in a hot dayHave fun!
TJ makes a good point about the location of the facing in regards to the location of insulationMy guess is that the faced fiberglass batts aren't taped which means that the vapour barrier isn't continuousI recommend peeling as much of the facing back as you can or at least cutting slits in the facing all over so it isn't a true vapour barrierThis would still allow any moisture to flow across the facing and still maintain the insulating value of the current faced battsIf you want to do things right, remove it all and start over.
I would have to go with the blown-in, considering what you have in there at presentThe blown-in will mix up with the old and cover the entire spacingNot to mention that todays products are superior over the insulation of old - like you said yours is!! I would be careful to not get it too far over the edge of the house and block any air infiltration - you know you need some up thereI did mine about three years ago, and a lesson I learned was to have a nice size piece of plywood up there to get on, and a rake to smooth it out - plus a light with an extension cord to see all the crannies you are shooting forYeah,don't forget a paper facemask (WalMart-cheap) and long sleeve shirt - it may be uncomfortable, but not as much as the coughing and scratching if you don't use themTwo people make this job go quickly, one to feed and the other to shootGood luck.
12 0z 357grams 75 feet^2 69677.28 cm^2 357 grams / 69677.28 cm^2 0.005124 grams/cm^2 2.7 x 0.005124 0.13822 mm
