I need to beef up the insulation in my house and am exhausted figuring out which way to go. Do I just add to the existing cellulose or go the extra mile and have the roof deck sprayed with open cell foam? I’ve read about horror stories regarding spray foam but have also read that it’s the best way to go. If it were new construction, I would foam the whole thing. I’m just wondering how successful doing a retro job would be. I’d really like input from some professionals out there. The house is 20 yrs old, 3000 sq ft with a high pitched roof and a large attic. Thanks.