I am repainting some upstairs bedrooms, and have noticed there is not a good seal around the sheetrock and ac vents. The attic above it is spray foam insulated, so a sealed system. I've noticed this around the bathroom vent fans as well. Here's a picture of the one in the current room I'm working on, most have much bigger gaps. You can see into the attic through the gaps.

If I'm understanding correctly, the attic above the room is spray-foamed on the roof deck, and so the rooms and the attic are part of the same thermal envelope? If true, would sealing this gap do anything?

You could always take a can of spray foam and spray a bead around the vent box from above, but I'm not sure I'd worry at all if you can't see the gap with the register installed.

That's what I was thinking. Not necessary since the home is spray foamed.

BenTheGoodAg said:

---

You could always take a can of spray foam and spray a bead around the vent box from above, but I'm not sure I'd worry at all if you can't see the gap with the register installed.

---

If you spray foam that area, and there is any vibration coming from the blower/furnace through the duct, you will transfer that vibration to the ceiling.

I would think I'm losing bought air to the attic. It's hotter or colder in the attic than the house. Obviously not as drastic as a non spray foamed one

Buy a small amount of insulation and stuff into the gaps? Should reduce overall airflow and insulate the gap without transferring vibration.

I'd silicon it.

You're still losing conditioned air to a non-conditioned space. Not as bad as a conventionally insulated structure, but still not where you want the energy going