Green Metal Roof Generates Heat

[kirkkw]

I recently bought a house around Austin Tx with garage/shop which has a green metal roof.

My second garage has a silver metal roof which is about 10 maybe even 15 degrees cooler than the green roofed garage.

The heat coming off that green metal roof feels like a heaviness or weight pressing down on my shoulders while standing. I have never experienced that sensation before due to heat and have lived in the middle east for many years, i.e. I understand what hot means. In fact it is 109 outside as I type this.

Anyway, it seems I have 4 options:
1. do nothing
2. install power vents on roof - the bldg has ridge vent and the entire perimeter has a vented soffit.
3. replace a perfectly good metal roof which is 10 years old - not really a reasonable option it seems
4 paint the roof

For option 4 what is a recommended paint or painting process/system that would stick to the metal roof and last a reasonable number of years?

Ken

 

[dcmus]

Re: Green Metal Room Generates Heat

Insulation? My shop, 30x50 is two sections. One with dropped ceiling and batt insulation, larger portion no insulation. Entire building is also green There's a noticable difference between the two spaces.

 

[DenisG]

Re: Green Metal Room Generates Heat

Evaporative cooling?
http://www.builditsolar.com/Experimental/RoofCooling.htm

 

[404]

Re: Green Metal Room Generates Heat

Do you mean room, roof, or both?

 

[kirkkw]

Re: Green Metal Room Generates Heat

Do you mean room, roof, or both?

Yes, silly me - I just saw that. No way to change the thread title is there?

 

[kirkkw]

Re: Green Metal Room Generates Heat

Do you mean room, roof, or both?

By the way "404" I like your sign lines:
The evolution of Google slogans:
2004 Don't Be Evil
2010 Evil is hard to define
2013 We build military robots
2015 I heard that

Funny thing, I work in the Ethics Office for a large corporate and we have mentioned Google's slogan in presentations. I think they no longer deserve to use that slogan.

Ken

 

[HOTFR8]

Titled changed to roof as request of original poster.

 

[404]

Re: Green Metal Room Generates Heat

By the way "404" I like your sign lines:
The evolution of Google slogans:
2004 Don't Be Evil
2010 Evil is hard to define
2013 We build military robots
2015 I heard that

Funny thing, I work in the Ethics Office for a large corporate and we have mentioned Google's slogan in presentations. I think they no longer deserve to use that slogan.

Ken

Thank you. Google, like all Great Revolutions started with pure noble ideas till it came time to break some eggs.

Heat from the sun is radiative, so a low absorptivity roof coating on the outside, along with a low emissivity coating on the inside surface reduces the energy the roof metal can re-radiate to to you. More info at the link.

http://coolroofs.org/

 

[djjsr]

My neighbor painted the roof of his pole barn white. I don't know what kind of paint he used but it smelled like Rustoleum. It's holding up well. I have a flat roof on my workshop that was originally black. I coated it with a white elastomeric coating and it made a BIG difference in the temperature.

 

[countryroad82]

When I had my garage built I had a white roof installed for this reason. Sure when you look at it from google earth it doesn't look very neat, but I never see the roof and it's so much cooler.

 

[Schurkey]

Don't they sell paint/coating for trailer-house roofs that's supposed to reduce the heat load inside? They've got metal roofs...

 

[nadogail]

In addition to painting the roof white you can add a seconded roof, over the first, with standoffs to allow air circulation and hold it a couple of inches above your existing roof.

This technique has been used for years on navy ships to reduce the temperature in ready service ammunition boxes.

 

[airsanford]

www.hytechsales.com

 

[matt_i]

I would do some testing and spray it down with a garden hose when its really hot. Probably every hour or so (guessing) but enough to keep it wet. Then see what the temp does inside the shop. Easy and cheap to test out to see if a more advanced roof irrigation system will do the trick for you.

 

[rieferman]

I would think that a reflective barrier installed on the underside of the roof (aka, the unfinished ceiling from inside your building) would block quite a bit of that radiant heat and be an inexpensive, easy solution to try as a first step.

When in the pole barn business in the past (almost always metal roofs, and very frequently unfinished interiors) we installed these types of barriers as a standard (unless customer requested that we skip it) and it helped with heat as well as condensation issues.

 

[GDPossehl]

AtticFoil

 

[black00lightning]

I've seen where they can use an outdoor spray foam on the outside of the roof. This would give you a light color on the roof plus a the insulating layer. Not sure what the price is but you should be able to ask around.

 

[rieferman]

AtticFoil

Yep, that's the idea. OP, I'd advise trying something like this before getting drastic with more complicated solutions. Hot metal roofs aren't a new phenomenon.

 

[xyster101]

As others have said, just a simple layer of bubble foil will reduce that heat tremendously. It is cheap too at ~$3.50 a sq/ft. Just staple it up to your rafters or trusses.

http://amzn.com/B006F3GAYQ

 

[boobag]

paint or insulation.

 

[kirkkw]

Yep, that's the idea. OP, I'd advise trying something like this before getting drastic with more complicated solutions. Hot metal roofs aren't a new phenomenon.

Yes, I think this is the way to go. I will call the manufacturer to iron out my questions.
Thanks for the help - I never thought of that as a solution.

Ken

 

[texas webb]

You can spray the under side with radiant barrier paint Sherwin or pittsburg then insulate but don't let insulation touch the radiant paint.Needs air gap.