I'm currently working on the R/I of a custom home. They have selected all 3" pots for the house. I'm currently in the area of 60 total with 40 being in insulated ceilings. It has become a standard with our builders for us to use air tite housings along with the Cool Blue vapour hats over top. The biggest issue now is that with the massivly oversized housing on these 3" pot lites, the arms on them wont extend far enough to hit the trusses with the Cool Blue over top. The only way we can see is to cut the vapor hat to fit the arms through, then reseal with tuck tape. This is going to be a time consuming process on an already rushed job. Anyone have any ideas or tricks from possible dealing with this sort of situation? The thoght did cross my mind that if we are using and insulated housing, wouldn't it be acceptable just to us standard poly to cover them or perhaps a large clear poly hat similar to what HVAC guys use over bath fans? In my opinion one the housing is insulated, there should be no requirment for 90 Degree rating for the vapor hat.
Sparky, The advantage of the 90 degree-rated hats is that you do not need to worry about exceeding their temperature rating even on a hot summer night with the lights on for an extended period of time. The insulation around a fixture does not prevent heat transfer from the fixture. It slows it down, so that the interior of the fixture runs hotter. However, over time, the area immediately inside of the hat does become heated. The question you are really asking: what is that temperature under the worst conditions? So perhaps you should err on the side of safety to protect yourself from liability. The thermal safety switch in the fixture should prevent ignition of surrounding poly if the poly is rated for a temperature that exceeds that of the thermal.
You have probably already considered that the hats are not necessary in the lower ceiling of a two story house, even when insulated for sound. Vapor transfer is an issue only when moving from a warm space through insulation into unheated space.
I am not familiar with these Cool Blue vapour seals. But if your housing brackets are not long enough for the joist spans, can you sandwich a 2 x 4 parallel to the joist on either side of the housing, which reduces your span by about 3". This way you may be able to stick with these cool blue vapour seals.
not sure why I cant find any info online about it. I do know that this product is intended for canada and possible not available in the US or other countries. This is the only link I can find at the moment.Home Depot Cool Blue
jay8 I have thought and used the 2x4 method before. The biggest problem seems to be that with the H36ICAT housings that we are using, the width of the nailing flange on the arms seems to be too wide. These vapour hats are not true square in the corners. They have a curve to them and thus dont allow for proper extension and mounting of the arms. I really am baffled as to why this would be as both products are made by cooper and should be compatable.
mikesh The housings that we are using are air tite with complete gaskets. I'm not sure if its just our builder, our company or new building code that is requiring the doubling up with the vapor hats over "sealed" housings.
I would bet it is the lack of current knowledge of the building inspectors. I say that since I have had this discussion with building inspectors and not that many realize the pot light can meet the requirement for vapour barrier. The department I work in has building inspections and plumbing inspections along with Electrical inspections so we are a pretty well coordinated. Nu teck makes a gasket box that meets the building code, vapour barrier requirement. Do you also have to install a poly pan with those boxes? Electrical inspectors should know there are vapour barrier requirements but unless there is an Alberta requirement the call is not an ELECTRICAL CODE call.
We have switched to the Nu Teck boxes as well but dont double up the poly hats with those style. Never really questioned that before now that you mention it. But after looking at the document in the link I posted I really can see the validity of doubling up with the cool blue poly hat and air tite housings. The problem still stands that the poly hat is too small or the housing and both recommended to work together from the manufacturer.