Hot Porch Roof

Forget the insulation.

Radiant barrier. Cheap, 95% effective, easy to install.

Obama says white paint everything

What kind of radiant barrier? I don't want it to look like aluminum foil. Maybe I could use the radiant barrier instead of insulation then the sheathing under that for looks.

Tony

Staple up a mylar foil space blanket? To the bottoms of the rafters?

Look good. Cook in the summer. What a choice.

You could do that. You could cover the radiant barrier with almost anything - even paint.

You should probably also plan on some way for the hot air to escape...

Why not just put in a fan? Blow that hot air out of there. ... and paint the roof white

A fan doesn't stop *radiant* heat.

I have been tempted! That part of the roof can not be seen from ground level anyway.

Not directly, but by conducting heat away from the sheathing, wouldn't a properly placed fan lower the temperature of the sheathing thus reducing the amount of heat it radiates?

If you can't see it, that's a good trick. It's often done on commercial buildings with flat roofs.

The reason you don't want to do it if the roof's visible is that turns an icky color and stains from the junk in the air.

I've considered ceiling fans but I don't know where I could properly place them to do the job. I think ceiling fans would just blow hot air all around me. If I'm lowering the temperature of the sheathing then I'm transferring the heat from the sheathing and into the air. I just don't see any easy way to use fans without a lot of turbulence, so I'd be blowing hot air all around. I'm tired, does that make any sense? BTW, the roof is 28' x 12' and a little more than a 1:12 pitch.

Do they use actual paint or the white stuff for mobile home roofs?

Sort of. If they're doing it right, they're using "roof paint" (not sure about the exact name). It's a thick, insulating, reflective paint. I've seen it in white and silver at the local DIY stores. It may come in other colors, but if heat is your main issue, you want one of those two.

Now, of your roof is in good shape and you're just looking to reflect more heat, there may be other options I'm not familiar with.

Yeah, ceiling fans without also insulating the roof probably wouldn't help. I meant a fan/fans somewhere where they could blow/draw air across the underside of the roof and out. That may not be possible depending on the design of your roof, and is probably not your best option by itself. I was just giving an example of how fans could prevent radiant heating, in response to this statement: "A fan doesn't stop *radiant* heat."

Foil is useless as condunctive insulation. Touching the hot roof accomplishes nothing. The styrofoam could help.

With the foil-side up it reflects the radiant heat. Perhaps I wasn't clear, or you're not familiar with the product - the foil adheres to the Styrofoam. I believe it's often used under vinyl siding.

Right. But it's 95% effective against radiant heat. You've got to have an air-gap and circulation to remove the heat, but it's a cheap and effective solution.

If you put the foil side "against the sheathing" then the heat will conduct from the roof to the foil.

You could put the foil side under the rafters, facing in the direction of the sheathing. It would also be a lot easier to install, you don't have to cut the foam to shove it in between the rafters.