Replies

1. 
   charlie_sullivan | Jan 30, 2016 02:29pm | #1

   Here are three options:

   1. A light colored "cool roof" that reflects most of the sun energy rather than heating up in the sun. That means re-roofing or perhaps painting. Look for materials certified in the EPA cool roofs program.

   2. Ordinary insulation between the roof and the ceiling. Between the roof and the ceiling, it's just ordinary heat flow and there's no need to do anything special on account of the source of the heat being radiation. But not knowing the construction, I'm not sure what to specifically recommend.

   3. A shiny metallic surface like aluminum sheets or foil exposed (not painted) on the ceiling. This would reduce radiation from the ceiling down toward the patio, even when the ceiling was hot. Of the three options, this might be easiest and cheapest, but it might not be acceptable aesthetically. You can use "radiant barrier" foil, or thicker aluminum plates. You have to be sure it's bare shiny aluminum facing down for it to work.

   If you want to consider option 2, maybe tell us more about the structure.

2. 
   davorradman | Apr 14, 2017 09:06am | #2

   Can it be done something like this, from bottom to top:
   - wood cladding -> insulation -> waterproofing -> white gravel

3. Expert Member
   Dana Dorsett | Apr 14, 2017 09:59am | #3

   A CRRC rated cool roof material with an SRI north of 75 would be a good start, lowering the peak roof deck temperature a few 10s of degrees compared to typical composite shingles. http://coolroofs.org/products/results

   The under side of the roof deck can be painted with a low-E paint (silvery colored, preferably with a specified emmissivity, and NOT a scammy ceramic sphere "insulating paint"), to limit the radiated heat flux.

   Only if those two measures prove inadequate would adding a true radiant barrier &/or bulk insulation make sense.

4. 
   davorradman | Apr 15, 2017 06:52am | #4

   Thanks Dana.

   Being from europe, I'd have to find similar products here.

   But at ~0.7$/sqft for 6in EPS, is it worth it?

5. Expert Member
   Dana Dorsett | Apr 15, 2017 09:58am | #5

   What is deemed "worth it" depends on your goals. With 6" of EPS the side facing the patio will be fairly close to the air temperature, which for a patio with a roof but not walls will be the temperature of the outdoor air.

   If the space is enclosed by reasonably air tight walls there may be an energy cost rationale for 6" EPS if the space is being actively air conditioned.

6. 
   davorradman | Apr 15, 2017 11:51am | #6

   Hm.. Thanks. So I'd have to find something that radiates heat back. It's an open patio, just roof.

7. 
   Anon3 | Apr 15, 2017 12:00pm | #7

   Radiant barrier is what you want.