Ceiling vapor barrier and can lights ?
I’m putting 6mil poly in as a vapor barrier on the ceiling prior to the drywall going up. The attic will have blown cellulose. What I’m curious about, is the best way to detail around can (recessed) lights. I will be using IC cans. The different ways that come to mind:
1. install cans, put up vapor barrier and then cut holes in barrier and caulk/foam seal it to the side of the can.
2. install vapor barrier baggy (or attach it up the sides of the ceiling joists) where the cans are going to be so that I could then just push it up and install the cans below it. When the insulation gets blown in, the poly will end up resting on the top of the can.
Option 1 seems pretty clumsy and I’m not sure how easy it would be to seal it to the can/housing. Option 2 assumes that the IC isn’t going to put off enough heat to bother the poly above it.
Anyone know how much heat a IC can puts off? Or anyone with a better way of dealing with this?
jt8
“Take your life in your own hands, and what happens? A terrible thing: no one to blame.” — Erica Mann Jong
Replies
John,
Halo makes airtight housings. You can just cut the poly at the round opening and caulk the poly to the bottom of the plate just near the downturned ring that sticks through the drywall. Poly tends to fail when it is baggy and wind can move it, and I think the top of the IC can will get hot enough to weaken it further. You have cellulose, so this is less of a big deal, since it helps to suppress convection.
Bill
Wrap the IC box in vapour barrier, tape it up like a christmas present. Cut an opening for the light. Slit the barrier in the corners to slide the hanger bars in and install them. When you vapour barier the cieling, cut out the holes for the lights, tape the cieling and box barriers ..
Ditto as BillBrennan. We use acoustic sealant - but watch out for zip or rotary tools spreading the sealant all over the room! My d/w guy didn't check the amount of sealant there, boy waht a mess
All the best...
To those who know - this may be obvious. To those who don't - I hope I've helped.
We use acoustic sealant - but watch out for zip or rotary tools spreading the sealant all over the room! My d/w guy didn't check the amount of sealant there, boy waht a mess
What is acoustic sealant? I've heard a couple people mention it and I've seen it recommended to seal poly (in an insulation book), but darned if I can find it hereabouts.
jt8
"Take your life in your own hands, and what happens? A terrible thing: no one to blame." -- Erica Mann Jong
Edited 2/19/2006 12:27 am by JohnT8
It's a black colored caulking, most home stores carry it. It's really messy to apply, but it sticks to anything
I am in the same boat as you I have 51 IC cans to deal with.
You could always use Tuck tape to seal the vopour barrier to the can. Tuck tape is the red tape that sticks to anything.
acoustic sealant is a non-hardening caulk, very messy and sticky (it sort of leaves strands like cheese on a pizza). It is used hereabouts to draft-proof and seal vapour barrier to framing, to itself, and to all penetrations thru said v.b. (such as elec boxes and can lights). Most lumber retailers will carrry it. use gasoline, WD40, kerosene, etc to clean up.All the best...
To those who know - this may be obvious. To those who don't - I hope I've helped.
You can use Juno IC-2 Recess cans with the factory gasket. Intall the cans, place the gasket around the ring, install your vapor barrior and cut out the holes. The factory gasket provides the seal with out the mess. you may have trouble finding the gaskets at a big box store but your local electrical supply house that deals in juno products can get them for you.