Insulation Question

[600SL]

My metal building came with 6" insulation for the roof and 4" insulation for the sides. These were rated at R19 and R13. It was a real PIA to handle and install this stuff. See first picture

But I recently decided to insulate the partition wall as one side may not be heated. I found this stuff called Prodex, which is only 5mm thick and very light weight and easy to install and RATED AT R17. All seems to be too good to be true. See second picture. The claim this stuff can be used for the exterior on the building as well. All seems to be too good to be true. See second picture. I'm actually thinking of putting another layer on the inside of my roof.

Any one have any first hand knowledge of this insulation.

Prodex Total 72 Inch Insulation

Prodex Total 72 Inch Insulation. This reflective insulation is used in metal buildings, pole barns and homes.

www.insulation4less.com

 

[rayra]

It might be effective as a radiant barrier, but likely won't work that well if it is in direct contact with a hot or cold surface. Kind of like those mylar emergency blankets.

I want to put a similar product across my attic rafters, gapped away from my roof deck, here in Vegas.

 

[toyotadriver]

Radiant barrier…..a little value. Keeping metal from sweating….a little value.

R17….not a chance. Highly over rated.



Nothing in this post should be misunderstood, interpreted, misinterpreted, or construed to be of a political nature.

 

[MongoTA]

"...which is only 5mm thick and very light weight and easy to install and RATED AT R17. All seems to be too good to be true."

It is. Too good to be true.

Insulation is supposed to only be marketed by the insulative value of the actual product itself, NOT by the achieved value of the material as a part of a building system assembly.

It goes along with the lines of XPS, at R5 per inch. The insulation is marketed as R5 per inch because that's what the insulative value of the material itself is, R5. Put it on top of subsoil and cover it with a concrete slab, it's R5. Put it in a wall with an air gap on each side, the assembly of the insulation plus air might see a higher R value, R7. But they can't market is as R7 because that's an assembly R value, not an insulative value. The manufacturers and marketers of thin foam (or thin bubble wrap) with reflective foil surfaces have been playing this R-value marketing game for years. They market it as an assembly value achieved in a laboratory under very specific circumstances.

Draw up a wall assembly, nothing fancy, drywall, 2-by studs, sheathing and siding on the exterior, and since you're going for net-zero, how about putting two layers of the Produx thin foam as your insulation somewhere in the assembly, for at least an R34 (2xR17 for the Produx alone) wall. Plus a bit more for the assembly. Take it to your AHJ and get their opinion, see if they say it meets R-20, R-19, or even R-13 requirements.

As others have written, the thin foam has some value, the foil faces when clean and not dust covered, have some value in some specific installations. But it's not an R-17 value in typical installations.

 

[billconner]

Nothing in this post should be misunderstood, interpreted, misinterpreted, or construed to be of a political nature.

I like that. I should add to all my posts.