need an air gap between metal roof and the radiant barrier. Put the foil directly on top of the foam board with the air gap above the foil. When the foil is in contact with the metal it will transfer heat through it instead of reflecting the heat. would be like hovering a frying pan over a stove instead of sitting it on the stove top.
@75slant6
10 ай бұрын
That’s how I built them. I put the radiant barrier directly on top of the foam board, then put 2x2 purlins on top, then metal.
@petesanchez557
9 ай бұрын
I’m thinking that concrete underneath heats both pretty evenly. I’ve seen many videos about that radiant barrier making a big difference on attics.
@75slant6
9 ай бұрын
That was my thinking as well, with both of them sitting on the same concrete, that wasn’t going to affect one over the other. I guess I could’ve set them both on a piece of foam but I didn’t think about that at the time.
@pinestumps8622
Жыл бұрын
Interesting setups! I have a book from the 80's on superinsulation techniques and one interesting factoid is over 60% of your thermal losses are due to air infiltration (air leaks). Maybe there are some tape products to seal off your foam and radiant barrier joints (Siga, ZIP)? When I build my shop, my plan is to just hire out 2" of closed cell foam in the walls and blow R60 fiberglass in the ceiling. After spending a day at a coworkers spray foam shop in the dead of summer I became a convert.
@75slant6
Жыл бұрын
I’d though about taping the seams of my radiant barrier, but I’m not sure yet if I will or not. 2” spray foam WAS my initial plan, but after figuring out what it’d cost to do the whole shop ($19k) I decided I’m gonna do something else. Lol
@Rambybambi
3 ай бұрын
There's a company that builds homes and garage with thick eps type 2 foam, 12" for roof and 8" for walls. Then encase it with concrete and that's it. No wood, metal ot anything else. It's like ICF but solid foam inside and it's supper diy friendly. No drywall and siding needed so it saves money. No more mold and wood rot.
@Larry-yb7zl
2 ай бұрын
It's a confusing subject. Radiant heat heats objects, not air, or our atmosphere would be too hot to live on earth. I believe your expectations were the issue here. Radiant heat is what you feel from electromagnetic energy. It's not accurately measured by a change in air temperature in the room but by its impact on an object it strikes. When radiant heat strikes an object it excites the molecular structure of any object in its path, some objects are more easily excitable than others, that's measurable and deemed as reflectance. A low reflectance object gains substantial heat energy thru radiation and its the object that changes the air temperature surrounding it as the object tries to dissipate the molecular heat. Radiant barrier is a highly reflective material which causes the majority of radiating energy to alter its path back into the air rather than allowing it to strike the object on the other side so long as there is an air gap on one side.
@75slant6
2 ай бұрын
@@Larry-yb7zl that makes sense. The objects that retain the heat, then slowly heat the air around them. Same reason that a radiant floor heat system takes longer to heat up a room than forced air but maintains that heat much better
@electricme100
7 ай бұрын
Maybe try putting them on a platform, or in the yard? The temperature might be affected by the heat capacity of the cement slab. A radiant barrier in a building wouldn't be so close to the pavement. Where was the ambient temp thermometer? It should be the same height or whatever- similar placement. It should be measuring the temperature in the shade.
@75slant6
5 ай бұрын
Yeah next time I do a test with them, I’ll set them on a piece of 2” foam to isolate the heat from the concrete. I was just using the local temperature on my phone for the ambient temp. I realize now that also wasn’t the most accurate way of doing that. Next time, I’ll get thermometers that do their own datalogging to make for more accurate and detailed graphs.
@papalong682
Ай бұрын
It would have been nice to have a control with no insulation.
@75slant6
Ай бұрын
@@papalong682 that would have been a good idea!
@AndreKochDre
5 ай бұрын
I believe the air gap needs to be between the radiant barrier and each outside surface material. So I guess this experiment just gives incorrect data mate.
@75slant6
5 ай бұрын
The air gap is between the radiant barrier and the outside material, as intended.
@ConspiredOne
10 ай бұрын
I think you should have put the radiant barrier on the inside.
@75slant6
10 ай бұрын
My thinking on putting it on the outside is stop as much of the heat as possible before it gets to the foam board.
@marklangkamp3151
9 ай бұрын
What part of the country do you live in?
@75slant6
9 ай бұрын
South central Ky.
@Luthz-jp8nh
3 ай бұрын
Your design is so bad that you can’t get a good study of temperature difference. My house temp at roof is 110 deg, at my barrier is at 97 deg then at my attic drops to 88. Apply it to your own house and you will be able to stay in your attic comfortably even temp outside is above 90 degrees .
@boombasticbass1374
11 ай бұрын
Bro you put the 2 houses on hot concrete.. air rises what you are measuring is the heat from the concrete slab 😫🤦🏼♂️
@75slant6
10 ай бұрын
There may be SOME truth to that. But the concrete under both was definitely cooler than the rest.
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