Current best practice is for attic HVAC equipment to be within the conditioned house envelope. Spray foam insulation on the ceiling, with the foam sealing the roof to the exterior house walls, achieves this goal. Blown fiberglass and radiant barrier does not. I would go with foam. Your summer cooling costs should be a whole lot less as well with the HVAC equipment in a cooler area.

@HU-867564120 Thanks -That definitely makes sense!

I guess my question is is that "best practice" scenario good for all situations/homes? Yes it's best for newer builds that are better sealed but what do I need to consider for a drafty humid old house. extra fans, ventilation, dehumidifiers/humidistats etc. I read general stmts that "humidity can be an issue w foam" but no real explanation of what that means or how do I make it not an issue :) . This was sort of the mssg from a couple installers and things I've read - there's just more to consider w an old house was the impression I got and I want to make sure I understand what all that is.

This was a the mssg I just got from my energy auditor - he's been in the electric, heating, cooling, energy business for decades and the green energy auditor for several new home builders now.

"I would not recommend foam attic unless you have a heat pump or a95% furnace. My new homes are all foam but are pre-designed for that. Contaminants are the concern w foam and humidity is a contaminant"

That was also what one installer sort of implied that many people are just insistent on foam because they assume it's the best - but its not the right fit for an old retro fit home the things required to make it right and that cost is not worth the return compared to the newer blown in.

I never trust just 1 or 2 opinions lol that's why I'm asking for more thoughts.