I see that you visited the Excessive dust/lint thread and trust you noticed the lack of resolution after 193 replies. If I've learned anything ,I've learned leopards never change their spots and neither do houzzers so you can expect the same opinions to be repeated.

To close leaks at ceiling fixtures you might give thought to Door And Window spray foam. It doesn't expand as much as others therefore not as messy, plus it cures soft enough to be torn out if fixture requires replacement in the future. Read mfgr's litature and MSD sheet to make your own decision on it's suitability. I've used it in dozens of buildings and in over 20 years non have self destructed nor been declared non-compliant.

Although you didn't ask,I have advice that could very well prove more valuable than plugging leaks. Close all door and windows , set hvac to cool OR fan on. Slightly crack entrance doors while holding your face in opening. If you feel a strong breeze on you face come back to tell me and I will walk you through diy solutions. If there is no breeze or only barely detectable that's great and no farther action needed. BTW I do not forbid nor discourage you hiring professionals to perform tests on your house if others tell you to do so. That's more disclaimers than advice but some parties have a knack for convincing speeches while waving code books,EPa regulations and other printed material whereas I only have common sense and experience to offer.

Hi, ker9,

The best time to perform air sealing in an attic is before installing insulation in new construction and before piling on more afterwards. You'll need to remove insulation in areas that need to be air sealed. While you're at it, don't pass up the opportunity to air seal any HVAC ducts that may be in the attic. Eliminating those leaks is usually the best return on your investment in air sealing. The U.S, Dept. of Energy sponsored development of an excellent air sealing guide for attics. https://www.energystar.gov/sites/default/files/asset/document/DOE_Air%20Sealing%20Guide%20for%20Contractos.pdf It's an easy read for DIYers and there are pictures to help any reading impaired or reading averse contractor you might hire.

I sealed our can lights to the drywall before installing the finish trim rings. Just used tubes of white acrylic latex caulk, caulked the can-to-drywall joint, then smoothed things with a finger. We had the house blower door tested and the tech was surprised that our cans weren't leaking! FWIW, it was easy to do.

Similarly, ducting could be caulked to the drywall as well, but as others above state, attic ductwork generally needs a fair amount of attic-side work to get things properly insulated and vapor sealed.

I also really like the minimal expanding foam-in-a-can for sealing areas. Just do check any "heat-emitting" fixtures like your can lights before you insulate/seal them. Some are made for insulation contact and some are not. As an aside, don't use foam-in-a-can near any open flames such as pilot lights, like a gas water heater for example. The cured insulation MAY not be a fire hazard if applied correctly but I know for a fact that the propellant is quite flammable! No, no, don't ask how I know!

BTW, if you switch to LED lighting, your can lights can probably be insulated how ever you choose but a non-code insulating method could become a fire hazard if someone changes back to incandescent bulbs in the future. Here is an example LED conversion kit.

https://www.warehouse-lighting.com/products/led-6-residential-downlight-retrofit-17w-120v-1200-lumens-3000k

I LOVED a LEEDS brand I used in an earlier home but some cans are not as easily converted as others so try one before you order a full set.....again, assuming this may help your insulating options.

Thank you to all of you, we appreciate the support.

We went thru hurricane Ian, which destroyed the living room ceiling. Finally got fixed but I don’t recall them putting down a new barrier when they pumped in the cellulose (hindsight I wish we had at least discussed alternatives but cellulose was already there so it is what it is). It’s been a couple months and still very dusty so we figure we need to seal the holes. There are a lot of holes/can lights and 4 ceiling fans (one isn’t installed yet in living room).

We did have our AC guy come out and inspect everything and he said we looked good from his perspective. We have reason to feel confidence in him.

Klem1, I don’t feel a rush of wind when AC is on and I open the door.

We will retrofit the cans with led, still trying to figure that out.

Going forward, we are getting a new roof hopefully to start in about two weeks. Will probably wait until that is done to take next steps but this gives us some things to think about and plan for.

I can’t edit, but adding the AC guy recommended sealing holes, he said it was still very dusty in attic.

No breeze when doors cracked is good news,I feared insulation installer damaged ac duct but it doesn't appear they did. Use high quality ac filters and change more often until dust issue is resolved.

We had the roof tear down done over the last two days (lots of pounding and banging) and the only noticeable debris from ceiling is where the missing ceiling fan should be (has box/electric no fan or cover plate). Will possibly be worse when tile is put down. Not sure what that tells me about dust problem.

What kind of filters do you use in ac system? Do they fit tight enough to prevent air detouring around them? How long does it take filters to become covered in dust/lint?