Cat on a hot tin roof


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Old 06-14-06, 04:59 PM
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Cat on a hot tin roof

Not really. But the tin roof is sure hot! (And I got your attention. )

Why?! The mobile home has that silvery coating on it. I felt it today in the 80 degree sun and it was pretty hot.

I felt another guys mobile home roof by my rental I own and he had some bozos last year coat it with blacktar. To my surprise the black tar was not THAT much hotter than the silver stuff...but it was hotter.

Someone I know foil faced the outside of the windows facing the sun as this absolutely knocked down the heat infiltration by what felt to my hand held 2 inches from the glass inside, doing before and after tests, by seemingly 95% ?

So then why does this other guy with a mobile home, who actually has a very nice uncoated, fairly shiny aluminum (maybe it is steel) tin roof....well, the roof is pretty hot!

So why is the tin roof hot and that aluminum coating product warm/hot...yet the foil is not? Is it because the foil material is less porous/more mirror like? Is part of it from the fact that the sun is not beating straight down on the window, as it would be if it was on the roof? (I think I am going to experiment and lay some foil outside in the sun, with the sun beating straight down on it, and feel...and maybe have some sheetmetal next to it and also some black tar paper next to it and feel all three.

Also I have noticed that white mobile home siding doesn't hardly even get warm in the direct sun. Very slight. But any color darker than white...even pale yellow, gets warm..and then colors darker than that become hotter of course. So I am considering experimenting and painting part of a mobile home roof white for the warm season, and maybe paint it black for the heating season. (I am toying with this thought.) They sell white rubber roofs they come and install on mobile home roofs with insulation-board beneath it, and this would have to do wonders for keeping the mobile home cool in the summer (but it be nice for it to be black in the winter). But the trouble is, they want $2-3,000 to install one of these roofs! So it like take 10 years (my guess) maybe to get the payback out of it. I hate that payback business! And that is why I am thinking about the paint idea instead.
 
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Old 06-14-06, 05:17 PM
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Yep, you got my attention

Don't know that I got any answers

IMO a roof over or double roof/insulation is always the best fix for MH roofs. Stops any leaks - present/future and helps to insulate the MH. All roofs are hot but colors obsorb more heat. IMO attic ventilation helps a lot but unless you build a roof over an attic is nonexistent in a MH. Silver paint reflects heat a little but has its limitations.

I don't know the whole story on aluminum foil but have heard it works well when used in place of a vapour barrier which is in the wall covered up. It would be interesting to learn more.

As far as I know all MH metal roofs are made of steel. Galvanized and shiny when new but sooner or later they need to be painted to prevent rust. The white elastromeric coatings seal leaks well and are supposed to reflect heat better than the fibered aluminum paint but they won't stop any rust.

The cat might need a glass if ice tea if you don't let him off the roof soon
 
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Old 06-14-06, 05:24 PM
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There are highly reflective roof coatings that can reduce the temperature inside a mobile home. There are tinted films for reducing heat from sun through windows. Keeping blinds closed on windows when sun is on that side of home does wonders to reduce temperature.
 
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Old 06-14-06, 05:40 PM
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The two coated roof mobile home I speak of are the late 60's/early 70's variety where there is no attic space and any heat directly transfers through the ceiling. I can actually FEEL warm when I touch the ceiling on a sunny day! Not good.

That is why it is most important to find the best product for reflecting the heat. (And obviously, that silvery aluminum coating is not cutting the mustard, unless it is somewhat better when it is new and is at it's shiniest) They don't sell a white coating that also stops rust formation? Rustoleum paint does. You'd think they'd have something for trailers.
 
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Old 06-14-06, 05:52 PM
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Originally Posted by DaVeBoy
They don't sell a white coating that also stops rust formation?
Elastromeric paint is latex based, that is why it does little to stop rust.
 
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Old 06-17-06, 02:35 PM
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Conducted experiment 1 hour ago out in hot sun. Took 3 foot square piece of cardboard and painted an area white, another black, another black, and over one of the black areas I put aluminum foil. Tilted it at sun like solar collector. A while later I felt the cardboard = warm...white paint area = just slight to the touch...black area = quite warm (obviously)...foiled-over black = when slipped my hand under it, the black felt cool to the touch.

Felt silver of mobile home rooftop = warm/hot. (hot tin roof syndrome) Felt white roll rof area that still shows some black between the white granules = fairly warm. Felt trailer roof by rental again that was tarred black and that was hot. Owner of trailer was gone. He was probably being broasted out of his trailer.


In conclusion, I would like to foil the mobile home roof. But because this is not to feasible, the next best would be to paint it white. Perhaps an epoxy or oil-base white. Maybe I'll experiment on just part of it first to see what happens after coating with this over that aluminum mobile home roof coating (that has weathered over the years, which may actually be a good thing, for adhesion...maybe.)
 
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Old 06-17-06, 02:49 PM
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You could apply white oil base enamel over the aluminum coating but the asphalt in the alum coating may bleed thru the white oil paint. It would have no leak sealing properties.

You should be able to apply the white elastromeric coating over weathered fibered aluminum paint with no problems. My only concern would be if a rust problem is present or becomes an issue, it would be better not to apply oil base over the latex but would be extra work to strip the latex so you could deal with the rust.

If the roof has never had a rust problem, has an oil base primer [alum coating will suffice] and is recoated as needed with latex I wouldn't expect rust to rear it's nasty head.
 
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Old 06-17-06, 03:57 PM
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I've cheapened out and gone up on the roof and hit rusty patches here and there, using cold galvanizing spray in a can. Did that last year. No rust showing.

In your post above, Marksr, you mention several types of coatings like the fibered aluminum, the elastomeric, oil and latex. Knowing what is on the mobile home roof now, which would be fibered aluminum coating that is old but intact (and has spots here and there with the galvanized spray that I did last year to cover the orange rust)...what would you apply to simply gain the heat reflective property and yet won't have paint peeling issues that could really make a mess of things for when the trailer must be recoated again, with...well, it be great if I could just keep recoating it with some kind of regular paint if it holds up to the weather... as this way I literally could switch from white in the late spring, to black in the fall.

Note to all readers... that if these older trailers were like conventional homes with attics, this wouldn't even be an issue, as an attic is vented and the heat or cold in the attic gets vented away. But not in these older trailers that have those rounded roofs, with no ventilation, with little insulation up there. And thusly, heat or cold transfers right through the ceiling.

With these older trailers it can be 87 degrees out and sunny and the inside of the trailer can get to be 95-100 on such days.
 
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Old 06-18-06, 05:30 AM
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Personally I would coat the roof with fibered aluminum paint. I prefer the the 'silver dollar' brand at lowes. IMO it rolls better and shines better than most of the the other brands and is priced comparetively. Applied correctly the coating will last [need to be redone] about 5 yrs.

My youngest son bought an older MH with a 3/12 pitch roof that was very rusty, 1 coat of silver dollar made it look new and is just now starting to let the rust bleed thru.

As always the best solution is a new roof complete with attic space/ventilation. I have an oder MH [flat roof] that I have built a house around complete with attic. Between the attic ventilation and extra insulation I often don't need to run the ac.
 
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Old 06-18-06, 03:41 PM
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I conducted another experiment today. I layed out the same stuff out in the sun as from my last post. But this time I brought outside a stainless steel really reflective bowl. (In fact, by looking at the bowl and the foil today, I went in my house to read a thermometer and I could hardly see... and what I saw was green!) I felt all the things like the other day. I felt the bowl too. Really HOT, even though it was reflective. Hmmmm. The foil was cool, so I thought maybe the reason the bowl was hot was due to it's thickness/thermal mass. So I took a big piece of foil and kept folding it many times to create thickness and layed it by the bowl. I felt each. The thick folded foil was still cool and the bowl was hot. Hmmmm. BUT...folded foil would still contain air layers, so not a real god indicator of anything, I guess.

I then flipped the bowl upside down and put a thermometer under it to see if the bowl was actually attracting heat. But to my surprise...UNDER the bowl was relatively cool! Hmmmm. Interesting and quite unexpected. I thought under the bowl it be like an attic in there at perhaps 150 degrees. But it was only 100, which was cooler than the 125 I had for that which was black.

Now I am going to conduct a test of all tests, in lieu of this finding. I am going to replicate the test about 4 times. I am going to take a shallow pan and place a thermometer in it. Then take a piece of galvanized sheetmetal that will cover this big square pan and paint it white, set it in the sun, and see what temperature develops in the pan, and forget about surface temperatures. It is what the temp is UNDER the paint or coating layer that counts! Then I will do the same repeat tests with new galvanized painted in black, then with that aluminum fiber mobile home roof coating, and then aluminum foil. And then compare all of these before committing to using the suggested mobile home roof coating.

I
 
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Old 06-18-06, 04:00 PM
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Originally Posted by marksr
Personally I would coat the roof with fibered aluminum paint. I prefer the the 'silver dollar' brand at lowes. IMO it rolls better and shines better than most of the the other brands and is priced comparetively. Applied correctly the coating will last [need to be redone] about 5 yrs.

My youngest son bought an older MH with a 3/12 pitch roof that was very rusty, 1 coat of silver dollar made it look new and is just now starting to let the rust bleed thru.

As always the best solution is a new roof complete with attic space/ventilation. I have an oder MH [flat roof] that I have built a house around complete with attic. Between the attic ventilation and extra insulation I often don't need to run the ac.
I would like to see a comparative sample of that stuff somewhere, up against some other brands. We have Menard's here and I don't know if they have that brand. I have another brand that I bought a couple years ago from them. I wonder if they have a web sirte with some good pics that can show it's reflective quality.

As far as redoing the roof by any means of construction: Not going that expensive route. That would exceed the worth of the trailer. Putting on one of those white rubber roofs over 2 inches of insulation board would cost enough at about $2500. I don't like the fact that it would take years to recover that money. That is why I am hoping by spreading some gallons of paint or coating up there can knock down temps up there, considerably.

The neighbor guy who had his mobile home roof painted black has much lower heat bills in the winter than the unit I own (same identical size units) and I should check with some of his past bills, if he has kept them, to see if when he had it coated black, if his bills became even CHEAPER...or not.

I'd LOVE to redo the roof entirely, but just like how back after the 1973 oil embargo when high gasoline Japanese cars started flooding the market...you had to pay a good deal for those cars for the privelege to be able to save on mpg's. I HATE that. I just want to save, and not have to pay to be able to save.

Same with vinyl siding. People get tired of having to paint all the time. So what do they do? Spend thousands and thousands of dollars on vinyl siding. I sure hope for the sake of people who own it that it holds up for more than 20 years as many plastics break down in the sun. Years ago I was called to this house and they had on one area of their house, the vinyl siding was getting brittle and cracking. Wouldn't that be the pits to stop paying $1500 every 7? years to PAINT the house... and then after 20 years, after you paid $8-10,000 for vinyl instead... to have to do it all over again in vinyl because it deteriorated?(Although there are condos I work on that are going on 20 years now and the vinyl there seems to be holding up.)
 
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Old 06-19-06, 04:10 PM
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I will indeed be doing this experiment. It may have to wait to this weekend...but if it's hot and sunny, I will do it. Or I will make the time to do it sooner as I hear it is supposed to get in the 90's here again.
 
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Old 06-23-06, 10:54 AM
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Mobile home roof

Some years back I lived in Louisiana (we know about hot) and worked at a place that had the offices in a mobile home. During summers I would go into the mh and find out they were almost as hot, just sitting there, as I was loading trucks out in the sun. I always wanted to try this idea (but never did): since we had a ton of pallets laying around, arrange a layer of pallets on the roof, and then put down some roofing paper so the mh would always be in the shade.

But when it comes to alternating paint colors from summer to winter- I was stumbling around Home Deep-o and saw 4x8 sheets of white plastic stuff, maybe 1/8" thick. Would it be an idea to lay sheets of that down for summer months, paint the other side black for winter, and figure out some way to keep it tied down? Or easier to get on the roof and put down new paint twice a year? As the paint builds up, watch out for low bridge clearances!
 
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Old 06-23-06, 12:33 PM
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Do another experiment. Go out and get a gallon of Cool Coat #2000 and try that. Use two coats, rolled on or brushed on. If you spray it on remove any filters.

I think you will be pleased with the results.
 
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Old 07-02-06, 03:02 PM
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Remember that test experiment I promised iI would do? Well, I had a go at it yesterday. But I abandoned it due to poor science. This is why:

I used a kettle, as the container, to monitor the temperature of the air inside. It was windy out. Even though the sheet metal covered the kettle, with the thermometer inside, completely,... the expected temps were not close to what I really believed they should have been. I think the reason they were lower is that the wind was stripping heat away at the side of the tall kettle. I really need to rerun the experiment with insulation around any container that I cover.

I will indeed do the experiment...sometime.
 
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Old 07-02-06, 03:03 PM
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Originally Posted by mdtaylor
Do another experiment. Go out and get a gallon of Cool Coat #2000 and try that. Use two coats, rolled on or brushed on. If you spray it on remove any filters.

I think you will be pleased with the results.
Gee. I missed seeing this post! Thanks. I'll look into that stuff.
 
 

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