possible to improve galvanized aluminum roof?
 

When I was building my storage shed, I learned too late about radiant-barrier decking, so chose a metal roof to reflect as much heat away as possible. What I wondered is if any other improvements would negate that reflective property, such as partial shading from camouflage netting, or use of the white sealant paint that is advertised to reduce heat on the roof. Is it counterproductive? Thank you.

Galvanized aluminum ?? I didn't realize they did that. Had to look it up.

If the surface facing the sun has high reflectivity, I would leave it alone.
If it had low reflectivity (dull gray?), maybe some white sealant paint would help.

If you had any kind of shading above the roof, that's going to help cut the heating inside.
I would not use netting that came in contact with the surface, since it might conduct
it's heat gain into the aluminum.

Being a Texan in a former life, I know that aluminum is going to be very hot on sunny days.
Radiant heat is going to cook anything near it, and it's going to warm the air inside the shed.

YouTube - ‪How Radiant Barrier Works - AtticFoil® Reflects Heat Coming Off The Roof‬‏

http://youtu.be/d-ShAiclBt4

Yes, it is galvanized aluminum. It is shiny. I have some ex-military surplus, so was considering putting up the camouflage-netting as an experiment. I'm intending to have it raised a couple of feet above the roof for an air space, Would the partial shading be effective, or would it trap reflected heat in the air space? I've never tried it, but thought perhaps some one else had. Thank you.

If a solar screen works (like this):
http://texaswindowsolutions.com/wp-c.../01/suntex.jpg
http://ecorenovator.org/forum/other-...provement.html
And these 80-90 percent screens are a very tight mesh. The don't allow air to pass
like a normal screen. You need to point a big fan right at them.
I plan to remove mine, when the cooling season is over.
Even then, we rarely open those windows.



I'm pretty sure that your camo netting will work to some degree.
Depending on the amount of shadows it cast on the roof.

I don't think it's going to trap hot air inside (under the netting), if it looks anything like regular camo netting.
If it trapped hot air inside, it wouldn't be very good stuff to use in the field..

http://library.uncg.edu/dp/wv/biggie/6/WV0400.6.040.jpg

Yes, anything above the roof that blocks light/heat is going to help keep the building cooler, but a vented roof is also going to help keep it cooler, zinc oxide is a good reflector and radiates heat well so that on it's own should help keep the roof cool so I wouldn't bother with painting it as most of those paints are a zinc oxide.

Believe it or not, galvanized aluminum metal roofing is considered a 'cool roof' material with it's high reflectivity of about 60%. When we had our house re-roofed we went with a very similar galvanized aluminum propanel - Cool Roof: Pro-Panel vs. Asphalt Shingle | EcoDaddyo.com.

I think there are about three things you could do to cool your shed:
1. Paint the roof white. That would certainly raise the solar reflectivity and that should help.
2. Vent the roof. I cleared out the eave vents and had a full ridge vent added to our roof. That allows the hot air to escape instead of just building up in the shed.
3. Add insulation beneath the roof. 1" or thicker foam sheet (maybe PolyIso foam with the foil layer facing up) beneath the roof should help block the heat radiating downward.

I think that insulation WITH venting between the foam and the roof would probably make the biggest difference.

FWIW,
Tim

Thanks for your thoughts on this subject. I have insulated the interior with rolled fiberglass (R-11), and punched holes to create a draft. The location of the shed happens to be on asphalt, which I believe is the reason the interior still gets warmer than I'd like (When working inside with the door open, I can get a suntan!). In order to help move the air, small vent fans are being added. I've looked at the white paint the hardware store sells, not even their employees could tell me if it would help or hurt the shiny aluminum by covering it. This was one reason camo-netting was considered-a temporary test.

When you said "The location of the shed happens to be on asphalt", it got me thinking about a tool you might need..
http://i46.photobucket.com/albums/f1...r/loadtest.jpg

A heat scanner is very handy when it comes to surveying heat sources.

Curious how that water heating has worked for you.

"3. Add insulation beneath the roof. 1" or thicker foam sheet (maybe PolyIso foam with the foil layer facing up) beneath the roof should help block the heat radiating downward."

That would work for sure. But, an air-gap sandwiched in there would help out..

~~
My PV assisted hot water isn't working so well these days. The sun is so high during
the best part of the day, with the tree tops hanging out so far, I get shade just after noon time.. :(
Need to oil up the saws!!

Your shed is located on asphalt? Ouch! Some sort of net or solar shading on the south side probably wouldn't hurt.

That's exactly what I meant, leave a vented gap between the roof and the PolyIso foam. Sorry if I wasn't clear.

Tim

I do use the rolled fiberglass under the roof decking, and on the walls, covered with a sheet of paneling.

The thing about these radiant barrier products, is that the stores which carry it can't answer any questions. The aluminum radiant barrier was too expensive to gamble blindly, so I went with traditional insulation.

For my double-wide doors, I used 3" medium-density foam board to save weight, but it has it has it's own shortcomings, mainly that the foam attracts certain flying wasps that want to to live in it. NO ONE told me this before I spent $4/sq. ft, and now I must schedule a bug bomb every 3-4 months.

I will test out the south-shading suggestion. IT may be more practical than covering the roof with camo. Thanks for the tip!

Is the fiberglass flush up against the roof deck? If not, you could place insulation trays aka soffit baffles between the fiberglass and the roof deck. Then you would need to add eave vents and a ridge vent. The insulation trays would connect the vents for air flow.

I did this on our house to allow air movement from the eave vents up to the ridge vent. Because your roof material is not a perfect solar reflector, some heat will radiate down through the roof deck. The soffit baffle allows air flow to vent the heat up through the ridge vent. That convection moves heat up and out of the roof and reduces the heat radiating downward into the shed.

With all that said... I wonder how much reflected solar heat you are getting from the asphalt. Using some sort of shade cloth (maybe even a foil/mylar faced tarp) to shade the south side (or open door side) of your shed could be a quicker and easier way to cool things off.

Good luck,
Tim

My insulation is all the way up against the decking, I don't look toward pulling it anytime soon.
I did install some hard points for canvas, will look at making a permanent shade spot on the south face. Thanks for the suggestion.