Radiant Barrier?

I am bidding a job in s.w. florida. The job is 5:12 with 30 yr. gaf shingles. The H.O. is requesting installation of a “radiant barrier”. The H.O. wishes to reduce energy costs.

I have no knowledge of a product that can be installed on the outside of the roof deck during the re-roof process that would achieve this H.O. goal.
Proper attic venting has already been discussed, however the H.O. wants more.

Any ideas,


I think radiant barriers go underneath the sheathing. Basically it is going to be an attic install job. I haven’t heard of anything that goes on top of the roof deck. You can also install them on top of the attic insulation. In my area, they just spray the trusses and sheathing with a special paint. I think it is an aluminum paint, but I could be mistaken.

There are various types of radiant barriers (outside of a ReflecTix or AlumaShield type OSB that has a super thin layer of tin foil like product on it; this is used for your decking).

If someone wanted to maximum insuation, it would go like this:

–OSB with ReflecTech / Reflectix / SolarBond type film on it (note: alum. film goes DOWN, or to the attic side, NOT up).

  • *Optional: Ventilated OSB decking with solar filmed underside & vented spacer strips to allow air circulation.
    –Radiosity type product sprayed on the UNDERSIDE of the OSB or decking.
    –Foamular sheets tacked from underneath to the OSB or decking.
    –Insulation batts stapled in between the trusses to the underside of the decking (R 19 @ a minimum).
    –A layer of a bubble packing type product that has an aluminum foil facing on both sides of the product.

& That would be a “balls to the wall” type installation, IMO. Very time consuming but very (VERY) energy efficient.

I’m in the middle of a 12x12 shed w/ 6:12 pitch (it’s for saddle gear & feed; will be air conditioned) & the deck is a SolarBond / ReflecTix type OSB, Atlas Summit in place of felt, foamular sheets over the vapor barrier, then horizontally laid 1x4 purlins with a snap lock / hidden screw metal panel laid over the top of this. I’m currently doing the walls & the roof panels are ‘soon to come’.

On the underside of the deck, I’m going to staple in a layer of the reflective bubble wrap stuff, then some R 19, another layer of the bubble wrap & finish off the underside with some 4x8 sheets of plywood. The ceiling will be vaulted… a smaller window A/C will go under the peak; that way I can keep it out of the horses reach.

I’ll post photos whenever I get it finished.

Note: the reason for the horizontal 1x4’s vs. going directly to the wall board is so there is some air ventilation behind there; it will allow for a bit of heat dissipation. The panels (roof & wall) are .26 galvanized, mill finish, & the walls are wrapped with a Tyvek type product.


I shared this with the H.O., and nows he’s back to the gaf 30 white(energy star) shingle like I told him at first.

Thanks for the detail ranchhand.