"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

Moisture issues are very climate-specific. You don't give enough information for any meaningful advice. Where I live, for example, it is generally advisable to seal up the attic and spray foam insulate the underside of the roof.

Start with the most important issue and its not the temperature of the attic. If the HVAC equipment and/or ducts are in the attic, you are losing a great deal of conditioned air to the attic space due to leaks and older minimum code insulation and you need to put an end to that waste. You also need to avoid bringing large amounts of hot/humid or cold air into the attic. That is never effective because so much of the heat in an attic is from infra-red radiation from the bottom of the roof deck that passes through air without being cooled. The modern solution is to insulate between the roof rafters and, if you like, add a ventilation space between the insulation and the roof deck so air that enters at the eaves can exit from the ridge and slowly dry the roof deck. Or , alternatively, you can seal the attic - its your choice. The attic space would then be partially conditioned by the HVAC air leaks and thin insulation which will keep it at a moderate temperature, dry and not musty and will reduce the heat and cooling losses from the house below. This is how new houses are built.

no foam mike_home, contractor is proposing blown insulation either fg or cellulose, only OP knows. just google baffles for attic ventilation OP. lots of pics there.baffles are installed on roof at eaves to do two things. one is to keep insulation at low point of eaves/soffits from clogging up air flow. the other is to establish a pathway for air to enter attic at soffit/eaves. attic ventilation that works is one of these three methods. all are stand alone, not strategies to be mixed. gable end vents. soffit/eaves may or may not have vents cut into them. soffit/eaves vents with ridge vent at peak of roof. or lastly soffit/eaves vents with passive vents installed on roof. the idea is to take air from soffits & vent from gable end, ridge vent or passive vents. google attic ventilation for more detailed info. prior to adding insulation minimal air sealing of air barrier (ceiling of living space) from living space to attic is done. for example recessed lights (Insulation contact not IC air tight recessed lights) would be addressed prior to insulation. much harder to dig out each area to be air sealed with newly installed insulation. fortunately, you can do a lot of air sealing from inside the living space. making as tight of an air barrier between living & attic spaces is one of the first steps to efficiency (and better air quality that goes along with it). it is easier to heat/cool a house with minimal air leakage. first area to air seal is house to attic. then floor to crawlspace (now that we have that info) once the air sealing is completed...then insulate. (3" closed cell foam installed on underside of floor, installed from under the house) if you have 8, 12 or 20+ inches of insulation & there is air moving through it...then it isn't performing. keep in mind that there is a diminishing return for more inches of insulation. the first 6" of insulation does most of the thermal barrier work, added insulation above this 6" saves you less & less $$ in utility costs. meeting code minimums is the least you can do. here in La. R0-30 is code, but people often have R-38. not a big jump in price, and not a big savings in utility costs. you make your own call on what to be installed. are you willing to do any work? (ie caulking etc) whats your location? best of luck