We’ve narrowed our search for replacing our old B.U.R… It’ll be either another B.U.R. or a modified bitumen. Final decision will be based on the price spread between the two, and what recoatings will cost prorated over the life ( 20 yrs. + we hope ) of the system. ( We have two bids in hand, and will be getting at least one more. )
Meanwhile, we’re researching what kind of insulation to install underneath. The roof has 4 air vents ( aprox. 4 x 9 in. ) along both sides of the long axis, and the space between the bottom of the roof and the top of the joists varies from 18 in. at the high end, to about 8 in. on the low side. Total area is about 12 squares.
Without removing everything, there’s no way to install batting or to spray foam between the joists and on top of the ceiling. So, that leaves us with two choices: Blowing in cellulose products, or blowing in fiberglass products.
When the roof was replaced on the small ( 700 sq. ft. ) rental we rehabbed next door, we went with fiberglass since our roofer had a preferred vendor they worked with who only installed fiberglass. The price was reasonable, and that roof had fewer, smaller, vents. It seemed to work. Our tenants stayed comfortable all summer, and even had to turn the A/C down because it was getting too chilly. ( It didn’t hurt that we had the A/C unit cleaned & serviced for the first time in decades. The 4 story Cottonwood in the neighbors back yard had, over the years, deposited a 3/4 in. blanket of “cotton” over the interior. Yuck! )
Our home is another story. We want to get the maximum R value we can, and that probably means some sort of cellulose product. Or does it? On paper, it has a higher R value, but what about “real life” situations?
Are there any significant differences between different cellulose products
either in R value, ease of proper installation, or longevity?
We heard a sales pitch years ago that said fiberglass was inert, not friendly to critters or bacteria, and couldn’t absorb water and cave-in the ceiling if there was a leak. (not an issue with a new roof that we intend to service properly. ) All of that sounds good, but staying warm & cool inexpensively is more important to us now, and probably will remain that way for the foreseeable future.
What would you suggest?
Thanks for your time and attention.