Re: painting roof white to reduce heat inside the house

Solar cooker does take the advantage of reflective surfaces. But do observe that the sun's reflection are redirected to a single point by virtue of a parabolic shaped reflector bowl

actually no, my solar cooker was nothing more than a GI sheet box painted flat black, sure it can't boil water but it can fry an egg. 😀

Hence if a reflective roof can thwart the increase of the inside temp only by a few hours before it achieves equilibrium, then its not really worth it.

does that assume that the sun intensity is constant throughout the day? there is only the 4 hours of intense sunlight, after that it's starts to diminish. and there are also clouds, and it only takes a few minutes of cloud cover to cool a GI roof.

and in my case there is only 4 hours of sun light that I need to shade my roof from and after that, my neighbor's 3 storey house shades our single storey bungalow. 😀

Re: painting roof white to reduce heat inside the house

yeah it assumes that you dont have any structures lending you a shade 🙂

if thats the case then a White roof will do you a lot of good. Wish i had two tall neighbors... hmmm

You should try the parabolic shaped bowl. Uses aluminum foil... I only read on it though... no actual hands on.

Good luck on your heat problem. I am planning to retrofit a giant fan/exhaust fan at the attic. To Take advantage of getting rid of hot air that gets stuck upstairs and bring in new air from down stairs. Will be useful only starting late afternoon.

Re: painting roof white to reduce heat inside the house

Eventually, I would like to do this: Passive Air Conditioning

Re: painting roof white to reduce heat inside the house

I think that you know better than a senior handyman, DiY By My Hand. And no need to ask opinion on things. you are very suitable to have your own web site, and if does happen, please let us know. 😎

Re: painting roof white to reduce heat inside the house

I think that you know better than a senior handyman, DiY By My Hand. And no need to ask opinion on things. you are very suitable to have your own web site, and if does happen, please let us know. 😎

Re: painting roof white to reduce heat inside the house

I think that you know better than a senior handyman, DiY By My Hand. And no need to ask opinion on things. you are very suitable to have your own web site, and if does happen, please let us know. 😎

you get me wrong el camarote, I welcome any opinion, good or bad. however, i've always been dubious of biased opinions, especially those that endorse a particular product with insufficient proof.

Re: painting roof white to reduce heat inside the house

Noted on that. Anyway, good luck on future projects.

Re: painting roof white to reduce heat inside the house

Hi,
That cooler you have drawn does not work in areas of relatively high humidity (i.e. Pinas). You probably will end up with a moldy house. Your problem is the heat you can feel from the ceiling. Getting rid of this heat will solve half your problems. One effective house cooling method is to provide ventilation in the loft (kisame).

Just my 2 cents.

Re: painting roof white to reduce heat inside the house

I'm seriously thinking of painting our roof white to reflect at least some of the heat. i'm thinking of using the stuff they used to paint sidewalks with. what is that stuff called and where can I get it?

Maybe you could try Destiny kooltex reflects 50% of the heat from the sun and can save aircon cost

Re: painting roof white to reduce heat inside the house

i was searching for roof insulation and was directed to this very

interesting discussion here about painting the roof WHITE

anyway, WHITE roof is fast becoming the trend even here in PI.

last year, 2 of my neighbors had already repainted their roof white

and one new 4 story factory building also has white roof with

continues opening on all 4 sides of the attic..

2 weeks ago , I decided to patch / paint our 15 yr old roof WHITE.

I went to the 3 big hardware stores along edsa balintawak and

bought some sample materials for testing,

since I never had the chance to used it before.

RUBBER paint, fine fiber mesh cloth and WHITE elastomeric paint

so far, im very happy with the result.

rubber paint is water base and is very easy to apply with brush

compared to other sticky cementitious sealant.

with the mesh, we were able to continuesly cover all the

bad GI's / flashing's horizontal and vertical joints..

and these are the temperature readings taken from an IR

thermometer yesterday saturday noon time
.

roof - WHITE elastomeric paint - 45 celsius

roof - dirty WHITE rubber paint on patching - 47 c

roof - remaining old red oxide paint - 58 c

room - 31 c

ceiling plywood - 35 c

ceiling plywood inside the attic - 38 c

Im also testing the reflective aluminum insulation and exhaust fan

for the attic..

i plan to finish painting the walls and roof before the heat

starts on february 4.

Re: painting roof white to reduce heat inside the house

roof - WHITE elastomeric paint - 45 celsius
roof - dirty WHITE rubber paint on patching - 47 c
roof - remaining old red oxide paint - 58 c

room - 31 c
ceiling plywood - 35 c
ceiling plywood inside the attic - 38 c

Interesting test. Been looking for quantitative comparisons like this for locally available products under local conditions. (Though the bottom line, energy/cooling cost, is harder to compare by controlled experiment.)

Can you say the specific brand and names you tested, e.g., was the first one FlexSeal CeramiCoat? (Which is not only white but ceramic. Don't know if it is considered elastomeric.)

Was your test method to re-paint two patches of the same roof and compare the two patches against the existing red oxide painted roof (= third patch), by measuring the temperature on the underside of the different patches?

Re: painting roof white to reduce heat inside the house

guad,

about branded local roof paints, I did not buy any of them but I did look at their samples

and scraped it with a pocket knife, they break or chip off or become powdery.

I have use that kind of paint before and what remains on our roof is red oxide.

I also scraped the new paint on the floor of sm annex parking lot,

its tough and I like to know what it is.

I am looking for something elastic that will move along with my old roof.

I do not know what will happen to the elastomeric white paint after

one year but its worth trying something new.

if red oxide comes out in 2012, I will paint again with expensive white rubber paint,

about flex seal ceramic , it is not elastomeric .

I bought samples from the waterproofing section.

I also do not trust leading USA paint companies even if they do test,

since they always test their WHITE insulation paint against black or GRAY.

their white vs white chalk will do.

I did read the outside and underside of our old GI roof,

the difference is less than one degree.

Re: painting roof white to reduce heat inside the house

I was also thinking of painting the roof with white epoxy enamel thinly, before painting it with regular enamel to thicken the coat..

In my experience, epoxy enamel is not good when directly expose to sunlight. so a regular enamel coat should cover it..

Re: painting roof white to reduce heat inside the house

By all means go ahead paint your roof white, there's nothing wrong with that and it will even beautify your house roofing, as long as you have carefully followed proper proceedures before applying your paints.

Di ba may kasabihan tayo na " light colors deflects heat, and dark colors
absorb heat ".

Painting your roofings white will only minimize small amount of hot air
inside your house, the best possible solution is that you install insulations under your roofs giving it a minimum spacing of 6 inches
between the underside of the roof and the above side of the insulation.

I am suggesting this because this is based on my actual experience
in my house. I have painted my roofs several times with Flexseal
elastomeric insulating paint, they call it "CERAMICOAT" and yet it is
still hot inside the house specially during the summer months. I did
experimented with my house since some parts of my house
doesn't have yet a ceiling and still under construction and so
LO and BEHOLD rooms with insulations and finished ceilings were truly very much cooler than rooms without insulations.

The rooms without insulations, you can really feel the heat penetrating from the GI roofing sheets down to the surface of the tables and other furnitures inside the house. May I simply suggest
in case you opt to install insulations in your ceilings, choose the thicker ones with double sided aluminum sheetings and believe you me you'll have cooler rooms inside your house.

I honestly hope this tip will be of great help to you and to all our friend at PHM. Pahabol tip, see if you can install also an exhaust ventilator
in some of your rooms to expel hot air coming from the windows.8)
thanks.

Re: painting roof white to reduce heat inside the house

Re FlexSeal 'ceramic' paint -- hard to say whether it is misleading or promising. Not enough posted info on the effectiveness of the actual product, as opposed to ceramics in general.

Best to call them up and ask if they have and can provide:
- results and description
- of actual controlled tests
- of the actual product (not NASA shuttle tiles or other brands)
- done in the Philippines (not by testing bodies abroad, e.g., ASTM, of similar materials abroad).

If you look into this, let us know what you find out.

Hello everyone. Long time lurker but first time poster on this forums.

So quad, if the tests for FlexSeal Ceramicoat is not to be done by ASTM standards, CRRC standards (Cool roof rating council) and other testing bodies abroad - who do you suggest conducts the tests here?

I'll offer a few to get the ball rolling. DOST - they dont conduct this type of tests. Private testing facilities - also dont conduct this kind of testings. So who do we turn to? - tests abroad. I know that this kinds of test for insulating coatings are kinda new, but they are now the trend. Either we embrace it or just stick to the old ways of insulating.

This link will help people understand what ceramic microspheres insulating coatings can do and what it cant do. Remember, there is no miracle product that will solve every problem - but this will probably help. On youtube: watch?v=D6RQpZODzx0&feature=related

The microspheres that is incorporated in FlexSeal Ceramicoat is actually borosilicate hollow glass. I will quote wikipedia on borosilate glass (not the hollow ones, we will discuss that later.

Quoted on wikipedia:

Borosilicate glass is a type of glass with the main glass-forming constituents silica and boron oxide. Borosilicate glasses are known for having very low coefficients of thermal expansion (~3 × 10−6 /°C at 20°C), making them resistant to thermal shock, more so than any other common glass. Such glass is less subject to thermal stress and is commonly used for the construction of reagent bottles.

Borosilicate glass has a very low thermal expansion coefficient, about one-third that of ordinary glass. This reduces material stresses caused by temperature gradients, thus making it more resistant to breaking. This makes it a popular material for objects like telescope mirrors, where it is essential to have very little deviation in shape. It is also used in the processing of high-level radioactive waste, where the waste is immobilised in the glass through a process known as vitrification (contrast with Synroc).

The thermal insulation tiles on the Space Shuttle are coated with a borosilicate glass. (Unquote)

3M has conducted many tests for this kind of microspheres and has spent millions of dollars for solar paints. Video is here: on youtube watch?v=T6ZBRoJdz9o

As well as BASF, the world's largest chemical company and AKZO NOBEL, one of the world's largest coating manufacturer. Incorporating microspheres into paints is a delicate procedure that if you put in in a paint and dispersed it too much - it breaks.

About white paints for heat reflection of roof, here is a video of Dr Steven Chu, Secretary of Dept of Energy of the USA talking about how a simple white roof paint can help - the video is here: on youtube watch?v=5wDIkKroOUQ

About the borosilicate hollow glass microspheres, it is has low thermal conductivity - around 0.04 W/mK. To give you an idea the thermal conductivity of other materials, I will show you some examples:

Cement - 1.73
Steel - 54
Glass - 1.05
Porcelain - 1.50
Rock - 7.0
Stainless Steel - 16

Just to name a few. So you see, putting microspheres into paint as a filler reduces its overall thermal conductivity - thus reducing heat absorbed. The white color part is for the solar reflectivity. And the microspheres is for the thermal emmissivity.

Hope I answered some of your questions on FlexSeal Ceramicoat.

Peace.