Cool roof coating over asphalt shingles? (OT)

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Bad Climber

Trad climber

The Lawless Border Regions

Topic Author's Original Post - Oct 18, 2018 - 08:25am PT

TACOID builders, contractors, et al.:

My wife and I will be moving to a new place in Bishop soon. Our current home was covered by a spray-on foam coating that added insulation and a white surface. It REALLY helped during the summer. The new place has a dark-ish asphalt shingle roof. I've been reading contradictory things about the consequences of coating a shingle roof. I've found one 2010 report from an industry group saying don't do it, but that seems to be contradicted by other sources I've read. The energy savings and comfort can't be denied, however. Have any of you done a white coating over shingles? We've got smokin' hot summers here, so I'm scheming on ways to save $$ and increase comfort. Would appreciate any experienced input especially.

Thanks!

BAd

fear

Ice climber

hartford, ct

Oct 18, 2018 - 08:44am PT

If the current layer of shingles is in good shape and the sheathing is likewise not rotted/good then I'd rely on whatever the manufacturer of that foam roofing material says. What's it called?

A single layer of asphalt shingles, in good condition, is frequently shingled right over around here to save some $$$ from the tearoff.

JLP

Social climber

The internet

Oct 18, 2018 - 09:03am PT

Sounds like a mess - and an easy way for someone to make money - spray that crap all over the place with zero prep then leave.

You can't replace a roof around here w/o a complete tear-off and a mid roof inspection for water shield, proper drip edge and flashing, etc.

The tried and true here is proper attic venting and lighter color shingles.

vvvv - attic fans are a waste, too, and can do more harm than good in a "loose" house with air passages into the attic space. Google around, lots of info on this stuff.

Roots

Mountain climber

Redmond, Oregon

Oct 18, 2018 - 09:04am PT

Attic fans are supposed to help tremendously.

......Or you can put bird feeders on your roof and let them birds turn it white for ya ; )

Reilly

Mountain climber

The Other Monrovia- CA

Oct 18, 2018 - 09:22am PT

BITD in Alaska the hippies would throw up a plywood ‘structure’ and call in an insulation
company to spray that icky orange foam over the whole thang. 🙄

Ed Hartouni

Trad climber

Livermore, CA

Oct 18, 2018 - 10:08am PT

possibly polyurethane foam?

I've been insulating my home more and more and while foams seem attractive the big down side is their flammability. So I've looked around for ignition resistant insulation, there are many alternatives to foam, and foam with fire retardants (the retardants) are not good for you.

I can't imagine using a plastic on the outside, they will breakdown under extended exposure to sunlight, and Bishop is at altitude, making this an even bigger issue.

And while the foams make a hermetic seal (initially), this prevents inspection of the roof.

John M

climber

Oct 18, 2018 - 11:20am PT

I can't imagine using a plastic on the outside, they will breakdown under extended exposure to sunlight, and Bishop is at altitude, making this an even bigger issue.

I have a foam roof on my mobile home. A foam roof is two layers. First the foam, then a coating over the foam which protects it from UV. If the coating is maintained, then the foam should last a very long time. some say 50+ years. Its the coating that has to be reapplied. that means cleaning with a pressure washer, then repairs are done ( this part I haven't figured out yet, it includes what to do with bubbles/blisters ), then a primer is applied, then 2 coats of the protective layer are applied. The protective layer is thick. Its not just a paint. It more like a rubber coating.

Its very important to maintain the coating. But if done properly, and the roof is solid, then the coating and the roof should last a long time. Durafoam, which is one of the main suppliers, says their coating should be reapplied after the first 5 years, then every 20 years.

I am though in the learning stages. I bought my mobile home here in Arizona with a foam roof.

fear

Ice climber

hartford, ct

Oct 18, 2018 - 11:39am PT

Interesting... do they do white powdercoated steel roofs out west?

Bad Climber

Trad climber

The Lawless Border Regions

Topic Author's Reply - Oct 18, 2018 - 11:47am PT

The spray-on foam on our current mobile is bomber and will last a long time. It was a multi-stage process from a well-established company that does residential and commercial buildings. Our new place is much better insulated. Old place is a '73 double-wide with absolutely crappy insulation. I'm shocked, really. What, in the 70's, no one knew about the values of insulation? Gah. Anyway, I'm looking for reflectivity. It was amazing how much the white on the roof helped. Anyone with experience re. reflective shingles? Downsides to a roll-on coating to whiten the existing roof? Just doing some research. Thanks.

BAd

Hoser

climber

Vancouver,Rome

Oct 18, 2018 - 12:03pm PT

Paint them white...can't hurt

Jim Clipper

climber

Oct 18, 2018 - 01:25pm PT

cover it in solar panels?

Russ Walling

Social climber

from Poofters Froth, Wyoming

Oct 18, 2018 - 02:00pm PT

Roll on the white elastomeric stuff... we do it all the time out here on the sand to flat roll roofing... shingles are no different, and all you are really trying to do is reflect the heat, not seal, insulate or any of that other gibberish.

5 gals for $100 or so... standard hovel will take about 15 gallons for a thick sloppy coat. It's not like you cant shingle over it if you decide it is not for you.

Brandon-

climber

The Granite State.

Oct 18, 2018 - 02:06pm PT

Russ is probably right, you don’t want to spend a lot of money. If it were me, and I had some money, I’d tear the whole thing off, plywood included, and have someone spray all of the rafter bays for an R-60. Then, button the thing back up. I’ve done it a bunch of times. Sounds cost prohibitive in your application.

hooblie

climber

from out where the anecdotes roam

Oct 18, 2018 - 02:21pm PT

adhesion counts.
prep, then prep again.

i pulled the trigger on the purchase of the silicon version
over latex despite the $100/pail premium. the reason being,
ponding was an issue in our case. elastic performance seemed better too.

we were applying the product over 45 years of accumulated tar patch puddles
on a roof that would best be described as an array of linked birdbaths.

like 6,000 sq ft of 'em.

the core problem was the thermal contraction/expansion
that comes with a 40 to 50 degree diurnal swing.

[Click to View YouTube Video]

i defer to your situation. other than delta T, none of the above applies ... :) ... but i concur,

white body thermal absorption is the increasingly elusive, in our times at least ... objective fact.

and tropicool by henry's
even over petroleum
did not disappoint

~~~~

not so sure about boot damage where the condition under foot is deep and pliable,
but white over dark with a brush full of next coat material is an obvious positive

Bad Climber

Trad climber

The Lawless Border Regions

Topic Author's Reply - Oct 18, 2018 - 05:00pm PT

Thanks, guys. The roof is in good shape as far as I can tell. I'll look more closely, but I saw NO cupping or curling of any sort, although we will be having a formal roof inspection. Sealing will not be the motive--just reflecting sun/heat. Seems to me an epic thorough sealing job might be overkill.

@Russ:

Is this kind of stuff yer talkin' about?

https://www.homedepot.com/p/Henry-4-75-Gal-687-Enviro-White-Roof-Coating-HE687406/202091034

@Brandon: Yeah, mega insulation would be ideal, but cost prohibitive.

BAd

Edit: I keep reading that coatings like this void any warranty on the shingles, not that that would apply in our sitch, I think. I keep reading from folks who do it anyway but with great results. Your thoughts?

Aeriq

Social climber

Location: It's a MisterE

Oct 18, 2018 - 05:50pm PT

I can only add per what fear said that I would determine HOW MANY layers of asphalt roofing are on the existing roof before adding another layer of whatever.

More than 3 would make me reconsider a permanent locked-in membrane over due to the pre-existing weight on the framework of a double-wide.

Glad you guys got the place - the view is unrivalled in the double-wide community of Bishop.

Cheers, Aeriq

Russ Walling

Social climber

from Poofters Froth, Wyoming

Oct 18, 2018 - 07:06pm PT

Yeah, thats the stuff Bad... looks like a new label, but the same stuff we use.

JLP

Social climber

The internet

Oct 18, 2018 - 07:45pm PT

If your roof is good and insulation somewhat adequate, why do anything? The insulation aspect of this foam layer sounds like more potential downsides than up, and the lighter color aspect it seems there are far cheaper ways to accomplish this - but again not seeing the ROI if the attic and insulation and venting are sound. One of the primary motivations for lighter color shingles is shingle life, but if you’re not replacing them, that’s not a factor. Otherwise this home depot product sounds like a bandaid fix for another problem that might be cheaper and more effectively solved directly - air sealing, added insulation, etc.

Contractor

Boulder climber

Oct 18, 2018 - 07:48pm PT

How tall is the attic space (pitch) or are there vaulted areas of the roof? How much insulation? How old is the wiring. Is the attic well vented.

Without knowing these thing- my two cents: I'd create an insulation barrier (R30) directly on top of the drywall. Let everything above that point breath according to industry standards.

Yes, what JLP said. I've used spray foam on flat roofs on some of the high dollar houses I've built. You really have to do your research. Going over shingles is a future nightmare as described a few post up and I'm not sure it's even done.

steve s

Trad climber

eldo

Oct 18, 2018 - 07:55pm PT

^^^ What Contractor said....let it breath! Extra insulation in lid. Also consider a thermostatically controlled attic fan, either in roof or in gable end . They really do work.
Not sure why anyone would add a layer of crap to their roof? Be careful.

Ken M

Mountain climber

Los Angeles, Ca

Oct 18, 2018 - 08:57pm PT

I have done a lot of research on this issue for the last decade, and it's surprising whats out there.

The specific solution that you ask about is definitely controversial, although it clearly is ok for flat roofs of asphalt rolls. In fact, NYC has a program to do this to all commercial buildings.

This is done a lot in Scottsdale/Az. Interesting to look at Sat pictures of the city.

However, there may be a much simpler process----Behr makes a paint specifically designed and recommended for asphalt shingles

https://www.homedepot.com/p/BEHR-1-gal-White-Reflective-Flat-Multi-Surface-Roof-Paint-06501/100164524?MERCH=REC-_-PIPHorizontal2_rr-_-204177723-_-100164524-_-N

There are also a couple of sites of guys who wanted a "try", without spending a lot of money. So what they did was whip up a batch of WHITEWASH, for less than $25 for the whole roof, just as a trial

https://www.builditsolar.com/Projects/Cooling/WhiteRoofExperiment/WhiteRoof.htm

Ken M

Mountain climber

Los Angeles, Ca

Oct 18, 2018 - 09:05pm PT

Here is a nice summary from Yale:

https://e360.yale.edu/features/urban-heat-can-white-roofs-help-cool-the-worlds-warming-cities

Bad Climber

Trad climber

The Lawless Border Regions

Topic Author's Reply - Oct 19, 2018 - 06:23am PT

@JLP -- Yeah, minor thread drift there. My current old-skool double wide is a '73 with a super low pitch metal roof. Spray foam has been great, but I'm not looking to foam the shingles, just add reflectivity if I can do so safely and cheaply enough. New place gets LOTS of sun while the old place has mega shade. Even with the shade, the white + insulation helped a lot. It was amazing to be up on the roof pre-foam job. The metal would get freakin' hot! Now cool as cucumber, baby.

Thanks Ken et al. Super interesting. Can't wait to read it. I've been really into energy efficient homes for a long time and wanted to build a straw bale years ago but not being contractor, the hassles seemed too much at the time.

For Bishop, we hit double wide gold!

BAd

toejahm

Trad climber

Chatsworth, CA

Oct 19, 2018 - 06:26am PT

Hello bad,
High-density spray foam with a polyurethane walking surface is what I believe you're considering. There are a ton of upsides, most already mentioned. The downsides are; maintenance every five years with UV and heat taking a toll on the finished surface. The finished surface is very undulating and lastly how do you tie into head walls, eaves, fascia, confined rakes without substantial modifications to your flashings. Spray foam use to be the product of choice, but commercial systems have switched, some time ago, to TPO roofs. There is a home in Calico canyon RR near the craft bouldering parking area that utilizes the roofing system you're thinking about, maybe someone here knows the owner.
Peace,
kenny
p.s. best advice is talk to the manufacturer and a preferred installer. Most if not all of the foam systems require specific installers, otherwise No Warranty.

Bad Climber

Trad climber

The Lawless Border Regions

Topic Author's Reply - Oct 19, 2018 - 06:39am PT

@Kenny and xCon:

Good points, but as I tried to clarify--no foamy on this roof. The crew who did the old double wide added a flashing damn all the way around then laid down a sealing coat which had to thoroughly dry. Then they laid down about 2" of the foam, then a couple of coats over that with some small gravel, which apparently discourages birds from pecking at the surface, which I guess is a thing. Manufacturer said we could probably go quite few years before any re-coating would be needed and that some maintenance like that would make the roof last indefinitely. Wasn't a cheap job. $$$

@Ken M: That Behr stuff looks like the bomb. I figured SOMEONE had to be making a paint for the job. I contacted Henry directly and they said NO to the use of any of their products on shingles.

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Chaz

Trad climber

greater Boss Angeles area

Oct 19, 2018 - 07:49am PT

They paint the shingles on these things and the buildings around them.

I don't know exactly what they use, but it comes out of a can and is applied just like paint.

jbaker

Trad climber

Redwood City, CA

Oct 19, 2018 - 10:34am PT

I've used the Behr reflective paint on a flat roof. It made a small but noticeable different in max temps. I think it would have made more difference if the house hadn't otherwise been poorly insulated with a lot of air movement (it was a redwood cabin built by hand in the 20s). It is a cheap and easy enough solution to give it try. If it doesn't work, you're only out a few bucks and an hour or two of labor.

Bad Climber

Trad climber

The Lawless Border Regions

Topic Author's Reply - Oct 19, 2018 - 11:01am PT

Hey, Chaz, that red roof is neat. It seems the Behr is reasonably priced. Key seems to be priming first. I'll prolly give it a shot in the spring.

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