"With the air tight IC recessed light cans you should still build air sealed enclosures around them because they leak a lot apparently. LEDs are a great choice for these locations especially without enclosures as they have a weaker "mini chimney" effect." in all my projects new and existing I've found many ways to seal IC cans. retrofit with inserts. then seal housing to sheetrock ceiling...from inside the house before putting trim kits in place. even 'air tight' trims don't stop the oversized cuts in sheetrock from leaking. I use a mastic tape made by Hardcast #1402 for all my holes in ceiling. more on this later. this seal described above is the best with no measurable air leakage. building boxes..maintaining the 4" air space on all sides & top of can light..also works, cheaper cost..harder install. problem is the 'legs' of the can lights that are attached to ceiling joists & properly sealing around them. this is where the air leakage occurs. I never use foam..because it shrinks over time, you have little control over where it goes & unless it is fire rated..shouldn't be next to heat producing areas. and yeah..I'm overly cautious about this. this method can be well done..and still leaky. foam installs I've seen online in videos put fg batts around recessed lights and foam them. I don't like this at all, and it is never done on my jobs. best of all is to use ICAT only, and use the hardcast tape to seal the cut between housing & sheetrock. Hardcast brand mastic tape #1402 is a 3" wide strong mastic tape. I perfer it over any other brand on the market. cut it into 1 1/2" wide strips and use it in full width depending on size of opening to be sealed. sticks to just about any clean dry surface...to the point of pulling paper off sheetrock if you try to remove it. so use it carefully. opeings at bath fans, supply boxes, stove vents, recessed lights..I use hardcast. use it once..and you'll understand why. not the cheapest on the market @ $22- $35 per 100' roll. but absolutely great stuff. while it is hard to describe the sealing of supply boxes with hardcast from inside the house..a picture shows it well. I'll attach one to this post. flgargoyle .. foil bubble foil is an overpriced product that performs no better than the cheaper radiant barriers. in my house with a tin roof..I have a single sided foil scrim fraft paper like what is used for ductwrap. I used button cap nails to attach it to the undersides of my rafters. with gable end vents..and 3 hurricanes later I've had to do a little repair on it..but it was worth the few bucks it cost me & the 2 mornings it took to install. good benefit in summer little to none in winter. my attic has fg batts on attic floor, one layer in joist bays the other unfaced layer laid across joists. no ducts, no equipment no recessed lights and a damn near perfect air barrier from living to attic space. ducts are in fur downs inside living space, vs air handler in side living space also. a bit over sized @ 2 tons with an whole house april air dehumidifier..also in conditined space. 4" media filter at return. 15SEER unit the addition I re-roofed last summer, batts in rafter bays 1" R-7 foil foam sheating lathes & gavalnized tin. as rafter/ceiling joists are 2x4 (yeah...go figure) the batts are R-13 with the R-7 gives me R-21 for this large bedroom. prior to this install the room was used for storage as it was too hot in summer & too cold in winter and too expensive & uncomfortable to use. with radiant barriers there always has to be a mininum of a 3/4" air space. thus the lathes on top of foil foam board under tin in addition & opposite install in big attic with rb under rafters with foil facing into attic space. gotta run...but wanted to share my take on things. oh here is the pic of the supply sealed from inside the house with hardcast tape. best of luck

Yes they work. If you have no intention of changing the roof for > 10 years, get one. It probably will be more than enough for a standard sized garage (~ 400 sq ft). However, I prefer having a passive venting solution. I just removed my solar attic fan after re-roofing with metal shakes. Changing from an asphalt based roofing system to a metal roof made a significant diff (almost 10 degrees centigrade).

Here's MY experience.We dont have to worry about "winter" conditions here in Houston.Its that simple. We do fight heat and humidity.I had over 30" of insulation blown into my attic,and then added one solar fan that is capable of handling 1600 sq.ft. My home is just over 2500 sq.ft. My solar fan installer agreed to install my second fan,BUT with a thermostat on it.It runs at 80 degrees and above but will not run at 65 degrees and under.The first fan will run as long as it is daylight,which is OK. I have ridge vents as well as gable vents,my entire West wall soffitt is a continous vent underneath it.This attic BREATHES!!! My elec. bill hasnt exceeded 207.00 yet and our AC thermostat is set at 77 during the day and 73 all night. Sat and Sundays are at 73 day and night. I think the three main ingredients in keeping a home cool in the summer are as follows, inusulation,insulation and insulation. I have never heard of having "too much". I also have storm windows and doors. I did spend additional on my AC system "plenium" and vent work to "balance" the house.In the end,i think it has paid off for ME. Good Luck......

"I can't grasp the all or none concept from Billl though. Basically how is creating a mini attic (still equalizing intake soffit sq inches to gable vent exhaust square inches) devaluing the effectiveness of the insulation? " Mini-attics don't work. All the batt types of insulation are mostly air. They only work as insulation if air is not flowing through them. If you are going to use them in a vented situation, you want to keep them away from major air movement. You don't want to create a tiny channel 1-2" directly next to them where all the air currents in the entire attic will need to flow. So, your effective options are to use a venting system so air can flow through the space but then keep the insulation by the floor so air isn't rushing by it OR insulate and seal off the rafters so there is no air movement. Trying to pick something halfway between the two just doesn't work.