Painted white roof drops house temps 8-10 degrees - Page 3

virginiajim · 07-07-11, 04:22 PM

A few years ago I looked into roof paint that incorporates ceramic reflective beads which could be applied to asphalt shingles from a company called Hy-Tech Insulating Roof Paint. I never could find information about an actual case of such an application, or what it looked like. The paint is expensive and you would prefer to have an attractive result. Has anyone experience with thermal reflective paint? Has the discussion here so far only involved white latex paint?

Jim in Smithfield, VA

tomboy mom · 07-07-11, 09:56 PM

Quote:

Originally Posted by Daox

Painting the roof would still be a good idea and would help. It will still get hot and the radiant barrier will still help once the roof has heated up.

if only the hoa would feel the same way

.

rhino 660 · 07-10-11, 01:57 PM

yea i thing my Nazi hoa will gas me for painting my roof white... maybe ill do it just to be a rebel, ive been contemplating it for about 2 years now lol.

rhino 660 · 03-15-12, 10:37 PM

well im preparing to go to my HOA and ask for premission to paint my roof white

Plantman · 03-20-12, 09:14 PM

So if heating load is greater than cooling load, it would be advantageous to have a dark roof that heats up in winter than a light roof that reflects heat in summer? What about greenhouse paint that is white but designed to last only through the warm part of the growing season and is mostly washed off by rain by the following winter when the sun is needed to heat the greenhouse?

Quote:

Originally Posted by S-F

Sounds great but in mixed temperature climates it's probably not such a good idea. I can live with a hot house easier than a cold house. I can survive 90 degrees inside but 0 degrees would be difficult.

MN Renovator · 03-20-12, 11:36 PM

Quote:

Originally Posted by Plantman

So if heating load is greater than cooling load, it would be advantageous to have a dark roof that heats up in winter than a light roof that reflects heat in summer? What about greenhouse paint that is white but designed to last only through the warm part of the growing season and is mostly washed off by rain by the following winter when the sun is needed to heat the greenhouse?

It doesn't work that way because your roof needs to stay cold in the winter or you'll have ice dams. This is one reason why there are issues if attics aren't either ventilated or directly insulated. I've been in my attic when its 30 degrees outside with no clouds and the sun up for hours when it wasn't covered in snow, you still need a coat. Don't forget once the black roof is covered in white snow, it doesn't matter what color your roof is anymore and there is less sun in the winter too which is why it is a much bigger deal in the summer.

Plantman · 03-21-12, 07:48 PM

What if you have a cathedral ceiling with no attic?

MN Renovator · 03-21-12, 08:01 PM

"or directly insulated." The roof has insulation directly against it(between the roof decking and ceiling) which will be similar. In a situation where there is a large cavity such as a flat ceiling and a sloped roof, that extra space needs to be vented unless the roof itself has insulation directly against it. In a case where there is a flat ceiling and an open cavity with insulation against the roof(called a 'hot roof'), the entire cavity is considered conditioned space since normally you wouldn't put insulation against both the roof and between the ceiling and the living space, its one or the other, otherwise issues with moisture become a real problem unless that space is vented and if its vented you wasted some money on insulated both sections. ..unless the 'insulation' against the roof is a reflective heat barrier but I don't consider those insulation like some people say they are. I like to use insulation as a term used for a barrier to conductive heat transfer, hopefully in conjunction with a proper convective heat barrier as part of the system.

S-F · 03-22-12, 04:13 PM

Yeah I agree that this should be only academic. If you have a vented roof I think there should be R-60 up there and then it doesn't matter what color your roof is.... unless you need to go up in the attic in the summer. In the summers here i New England where everyone has back shingles I am SUFFERING. Sure the home owners talk about how cool the house is after R-60 is in place but putting it there is miserable. Nothing like blowing cellulose in a cramped space in 130 degree heat. Even if you use good cellulose that isn't too dusty, like the Home Depot stuff, you still walk away completely covered is grey glue. When I put a metal roof on my house it's not going to be black! Also on the menu for this weekend is to install three lights in the attic with a switch So I can see what I'm doing when I air seal it to the hit in the summer. Beats the hell outta carrying a drop light around.

Xringer · 03-22-12, 06:46 PM

It's almost 8PM and my attic is still 91 deg F.
Musta been cooking up there this afternoon!

07-07-11, 04:22 PM	#21
virginiajim Lurking Renovator Join Date: Sep 2010 Posts: 3 Thanks: 3 Thanked 0 Times in 0 Posts	Sources of roof paint A few years ago I looked into roof paint that incorporates ceramic reflective beads which could be applied to asphalt shingles from a company called Hy-Tech Insulating Roof Paint. I never could find information about an actual case of such an application, or what it looked like. The paint is expensive and you would prefer to have an attractive result. Has anyone experience with thermal reflective paint? Has the discussion here so far only involved white latex paint? Jim in Smithfield, VA

03-15-12, 10:37 PM	#24
rhino 660 Apprentice EcoRenovator Join Date: Oct 2010 Posts: 105 Thanks: 0 Thanked 10 Times in 8 Posts	well im preparing to go to my HOA and ask for premission to paint my roof white __________________ 2 ton geo unit 2400' HDPE slinkey 4KW solar with battery backup $8.98 power bill

03-22-12, 06:46 PM	#30
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	It's almost 8PM and my attic is still 91 deg F. Musta been cooking up there this afternoon! __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

07-10-11, 01:57 PM	#23
rhino 660 Apprentice EcoRenovator Join Date: Oct 2010 Posts: 105 Thanks: 0 Thanked 10 Times in 8 Posts	yea i thing my Nazi hoa will gas me for painting my roof white... maybe ill do it just to be a rebel, ive been contemplating it for about 2 years now lol.

03-21-12, 07:48 PM	#27
Plantman Lurking Renovator Join Date: Feb 2012 Location: Angola, IN Posts: 24 Thanks: 0 Thanked 4 Times in 3 Posts	What if you have a cathedral ceiling with no attic?

03-21-12, 08:01 PM	#28
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 940 Thanks: 41 Thanked 117 Times in 91 Posts	"or directly insulated." The roof has insulation directly against it(between the roof decking and ceiling) which will be similar. In a situation where there is a large cavity such as a flat ceiling and a sloped roof, that extra space needs to be vented unless the roof itself has insulation directly against it. In a case where there is a flat ceiling and an open cavity with insulation against the roof(called a 'hot roof'), the entire cavity is considered conditioned space since normally you wouldn't put insulation against both the roof and between the ceiling and the living space, its one or the other, otherwise issues with moisture become a real problem unless that space is vented and if its vented you wasted some money on insulated both sections. ..unless the 'insulation' against the roof is a reflective heat barrier but I don't consider those insulation like some people say they are. I like to use insulation as a term used for a barrier to conductive heat transfer, hopefully in conjunction with a proper convective heat barrier as part of the system.