Insulation, Radiant and Vapor Barriers - Caulking ceiling boxes, worth the effort?

I downloaded a US Energy Dept file on sealing household air leaks. One of the suggestions was caulking around overhead light fixture junction boxes from the attic side. Seems like a lot of work for minimal gains.

Does anyone think that's a significant source of heat loss? I have 12" of insulation in my attic and 5 overhead fixtures.

If your attic insulation is fiberglass it won't stop air flow, and if the gap around those boxes is just an eighth of an inch you would have about a 4" diameter hole into your attic. AND it gets worse, the air pressure at the ceiling is the highest and the air that leaks out is going into the attic where it deposits moisture and heat that create additional problems. It does sound like a pain, but in terms of a SIR "savings to investment ratio" the effort is one of the best investments you can make.

If some of the lights are difficult to get to, try caulking or masking from below. If you have blown in cellulose, they are all set, the cellulose blocks enough air flow.

Now, would you air seal a receptacle box on an inside wall? Yes, it's just as important as the lights you are looking at and a lot easier to get to. If you are interested in why, I'll explain.

Bud

I've caulked all (I think) my outlets, switch boxes, and fixtures. I had to replace all the plates and fixtures, so it only took a few minutes extra. I also used the foam plate sealers where I could. Can I tell an actual difference..no..but the incense smoke doesn't blow around them anymore.

I'd love to get in the attic and seal all the wire penetrations in the top plates..but I just don't think that will happen in this house.

It does sound like a pain, but in terms of a SIR "savings to investment ratio" the effort is one of the best investments you can make.

If some of the lights are difficult to get to, try caulking or masking from below. If you have blown in cellulose, they are all set, the cellulose blocks enough air flow.
Bud

Thanks. The original insulation was loose fill and is pink. Could that be cellulose or does the pink mean it's fiberglas? I have added 6" fiberglas batts on top of that. Other than having to crawl thru a 24" opening in a linen closet to get to the attic, it probably won't be too bad.

Pink is fiberglass, cellulose is ground up newspaper, packs tight and works well. Since you have added batts it won't be too hard getting to those boxes.

Since all electrical boxes and penetrations into any wall cavity leak air behind the sheetrock, sealing them is best as that air can easily find it's way into the attic.

Bud

It's hard to caulk a box since there are so many holes and even the "knock-out's" aren't sealed so you have to caulk them too.

I find it much easier to use a can of spray foam on the top of the box, I just spray a cacoon over the box and it's sealed tight, wires and all.

Just don't make the home to tight! Homes need 60-80 CFM of ventilation during occupied times for good IAQ

Is that why my windows and ever my walls started dripping water on cold days after I sealed my home?

Yep! You need more ventilation in your home! Make sure you run your bath fans for at least 20 minutes after showering.

I always ran the fan for 20 minutes afterwards, but the problem is that no new air could come into my home. Now I leave one window on the other end of the house opened most of the time. It's a shame that I have to let that hot Summer air into the house, but I guess outside air is better than 130 degree attic air.

From where you live, I had to smile when I read your question. As others have said about the chase effect, I'll just mention: Ice Dams, Growing Mold, Wood Rotting, from all that warm, moist air rising into your attic and cooling. You probably read about insulating skylights, and bath fan ducts too, right?

I'd pull the fixture and use foil tape at all gaps, because I don't like attics - and they don't like me. ```` Be safe,GBAR