Radiant Barrier RadiantGUARD Ultima FOIL Insulation Roll 1000 sq ft | 48-inch by 250-feet | U-1000-B | Heavy Duty Perforated Foil Radiant Barrier Attic Insulation - Blocks 97% of Heat

Full disclosure - I am a perfectionist. I have covered about 50% of my roof (in Nashville TN in June 2018 with temps over 90 degrees. I use an ETEKCITY infrared thermoment ("gun") to measure temps of attic. I keep a daily/hourly record as I install and routinely measure the same exact spots: the roof planking (from the inside without any Radiant Guard (RG), the nearby 2x4 trust/joist that supports the roof and also not covered with RG, and the nearby section (inches away) that IS covered (trust-to-trust to the Roof Ridge).One measurement taken, when the outside temperature on a cloudy day was 85 degrees, had the inside of the roof at 146 degrees, the nearby trust was 126 and the nearby RG in the covered section was 108. First factoid - cover everything possible. The trusts are heated by conduction by the roof and also by the attic air and radiates into the attic if not covered. One of the many youtubes and documents I read said to think of the objects in the attic as charcoal briquettes - they heat up (fairly quick) and SLOWLY dissipate that heat even as outside temperatures drop. TRUE.Another day, outside temp was 82, roof was 129, truss was 106 and RG was 94 - same EXACT spots as above and no changes in coverage. What is clear is that as the outside and roof temperature increase (roof has increased by as much as 50 degrees from 8 to 2PM), the truss temperature lags behind the roof and the RG lags behind both. The RG thus helps mitigate the "charcoal briquette" effect.Here are lessons learned. If your attic is not cluttered like mine with lots of wires and ductwork, then you SHOULD run the foil horizontally as is recommended for several reasons. It is easier and more likely to be successful. It covers the truss. It provides a better "seal" between the trusses. HOWEVER keep in mind in mind that building construction is far from perfect and trusts are not all the same distance from the next truss. I have had a truss angled by an inch over 8 feet. It is worthwhile to pre-measure and add an inch or two to be sure and either wrap the excess or cut it after install.For those of us with a LOT of ductwork and nominal flooring, you may be forced to lay vertical strips. The angling of the truss can be a big problem especially if the attic floor is not finished because measuring up and down the vertical trusts is a big hassle. Your best bet is to seize whatever opportunities you face. (e.g.,) If there are three trusses that you can more easily get to, cut 3x24" (or more) and staple it horizontally if you can. I tried cutting vertical strips on the length of the RG roll and stapling it vertically and cannot tell you how many times I was faced with gaps and had to remove the staples, realign and re-staple. I have had to do a lot of customizing work around ducts, straps, vertical vent pipes, sections that are difficult to reach/get to, etc. etc.With ~50% done, it is not perfect but very close. This stuff works but keep in mind that there are a LOT of factors regarding the temperature you will FEEL in the attic. The two examples above show that a 3 degree outside temp difference somehow had a (146-129) 17 degree inside roof temp difference.I am holding judgment on whether I can actually FEEL the overall effect of the RG in the attic. Way too many factors (clouds, breeze, temp in previous days, etc) including my judgment. But as a perfectionist and degrees in mathematics, I can tell you that my temperature gun is definitely showing what is happening to the roof, trusses and RG. I intend to update this when I'm done.A power staple gun is recommended although I have done this with an old manual staple gun. Getting leverage to push is often problematic.

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This stuff is not like the cheapo stuff they have for sale on ebay. The eBay stuff is super flimsy like a plastic film. This stuff is like what you wrap a 30lb turkey in at Thanksgiving. Hell, if you're not worried about the plastic coating burning off you can certainly cook an entire platoon's Thanksgiving in this stuff and then use it to patch up the ISS.Cutting it is easy with a box knife. It'll dull it after about 30 cuts but it's worth using one to save time. The rolls are 4ft wide which makes covering a lot of area easy, but a challenge when unrolling it to cut. We use a broomstick and suspended it between two of our city-provided trash cans so we could pull it out like at the fabric store.Make sure you add 8" or so to each cut because your attic is no 100% square. You'll need the extra to cover and make it easier. If you come up short it just wastes material. If you come up long (same thing lol) I just leave the overlap.It's perforated which is nice so that it's not a vapor barrier. Installing this immediately blocks the heat you feel radiating off the roof deck. Now you need to understand this is NOT insulation or a replacement for it. Insulation actually blocks the movement of heated air from one side to another. This stuff blocks/reflects the RADIANT part of the heat. Think holding a piece of aluminum foil in front of you when you open the oven. It'll block the part that comes out immediately but not the air that flows out.Use a staple gun. We bought a Milwaukee M12 staple gun to save time. You'll use thousands of staples in an attic. It'll save your hand, trust me. 1/2" is good enough.Maneuvering in the attic with a 10ft long piece of aluminum foil on your head is difficult. Have a friend or family member help. This is not a fault of the product, because honestly any blanket over your head in an attic is going to cause maneuverability problems.Overall I think it's a decent product, and when used with good normal insulation will reduce the heat load on your house.

I've always had a problem with my house's second floor heating up 8 to 10 degrees higher than the first floor during the summer months. I was on a quest to find out why this is the case, until I came across a bunch of youtube videos regarding the importance of blocking radiation heat through the roof in the attic. Heat from the sun radiates into the attic space, conducts and permeates through blown in or insulation bats then onto the ceiling sheetrock, thus heating up the space below the ceiling, no matter how thick the insulation is in the attic is. This stuff reflects back MOST of the radiation heat. I used the laying over the blown-in insulation method since I live in the snow belt, and this helps with reflecting the escaping heated air back down during the winter. The temp difference between the 2nd and 1st floor now is only 2 degrees at most after an entire day with 95 degree ambient temp outside.People also need to understand the importance of air sealing the attic around the top plates and around electrical conduits and pipes, in order to keep heated or cooled air in the living space. I actually spent more than 2 weeks building an attic catwalk and precariously maneuvering around the entire attic, pulled back blown-in insulation and used around 6 cans of Great Stuff to seal top plates and conduit/pipe gaps. The combination of both has made the entire house very comfortable. I also have this installed in the garage's attic, nailed to the roof rafters, and it reduced the garage space 15 to 20 degree F, with no insulation in the garage's attic. VERY SATISIFIED with 2 rolls of this, more bang for the buck than using more insulation.