I put in blown-in cellulose last summer—midwest climate, composite roof. Honestly, the attic felt cooler, but the difference inside was pretty subtle....

I get where you’re coming from—manual cleaning is definitely thorough, but I just can’t keep up with it since I’ve got a two-story and a ton of trees....

I’ve had similar results with the algae-resistant shingles—less streaking for a while, but after about 8 years, the green stuff creeps back in. I’m in...