Water-cooling of the roof

[fredlk]

PU Foam and white paint on top of the roof. Preferably glossy. Sunshine literally bounces off of it.

Or better still: PU-Foam and a glossy white Clean Colorbond roof.

Today the temperature reached the highest level here so far this year, 32.9 inside my study (and also 32.9 in the shade in the garden).

[schuimpge]

PU Foam and white paint on top of the roof. Preferably glossy. Sunshine literally bounces off of it.

Or better still: PU-Foam and a glossy white Clean Colorbond roof.

Today the temperature reached the highest level here so far this year, 32.9 inside my study (and also 32.9 in the shade in the garden).

I was indeed thinking of your roof Fred while typing that answer...

[oil]

If you are going to use water on the roof then why not plant something it?

as for insulation goes that is definatly the best

PU-Foam is better.

is PU Foam payable, and can it stand the UV light here, every bit of plastic which is the sun here to long is trash within a year

[schuimpge]

is PU Foam payable, and can it stand the UV light here, every bit of plastic which is the sun here to long is trash within a year

My first roof was done about 6 years ago. The company that did it guarantees 5 years but the foam normally last for minimum 20 years.
It's applied under the roof, not on top. So UV is not really a concern although PU-Foam is said to be almost undestructible, even from UV.

The cost lies around THB 550 to 600 p/sqmt for the roof that I did just a couple of weeks ago.

[fredlk]

can it stand the UV light here

Yes it can, especially since it is sprayed on the underside of the roof and is kept in the dark forever. I think it's guaranteed for 25 years or so.

every bit of plastic which is the sun here to long is trash within a year

PU-Foam is not plastic, but I have white plastic pool-side recliners that I bought here and which have been outside in the sun and all weather every day since 2008. They're still in perfect condition.

[fredlk]

The company that did it guarantees 5 years but the foam normally last for minimum 20 years.

I could be getting my metaphors mixed, my wires crossed and my facts wrong.

[schuimpge]

The company that did it guarantees 5 years but the foam normally last for minimum 20 years.

I could be getting my metaphors mixed, my wires crossed and my facts wrong.

Your recliner chairs might resist the sun and UV and all that, but maybe you should get some shade....

[oil]

How thick is that layer of PU which goes for 550 TB?
and does anybody know the R - Value of that one

[fredlk]

How thick is that layer of PU which goes for 550 TB?

25 millimetres.

[fredlk]

does anybody know the R - Value of that one

From http://en.wikipedia.org/wiki/Spray_foams_(insulation):

"Polyurethane is a closed-cell foam insulation material that contains a low-conductivity gas in its cells. As a result of the high thermal resistance of the gas, spray polyurethane insulation typically has an R-value around R-5 to R-6 per inch. In comparison, blown fiberglass typically has an R-Value of only R-2 to R-4 per inch."

[oil]

does anybody know the R - Value of that one

From http://en.wikipedia.org/wiki/Spray_foams_(insulation):

"Polyurethane is a closed-cell foam insulation material that contains a low-conductivity gas in its cells. As a result of the high thermal resistance of the gas, spray polyurethane insulation typically has an R-value around R-5 to R-6 per inch. In comparison, blown fiberglass typically has an R-Value of only R-2 to R-4 per inch."

now this gets odd, LOL

in this wiki article it says ..

Around most of the world, R-values are given in SI units, typically square-metre kelvin per watt or m2·K/W (or equally, m2·°C/W). In the United States customary units, R-values are given in units of ft2·°F·hr/Btu. It is particularly easy to confuse SI and US R-values, because R-values both in the US and elsewhere are often cited without their units, e.g., R-3.5. Usually, however, the correct units can be inferred from the context and from the magnitudes of the values. United States R-values are approximately six times SI R-values.

cause i checked on another site, and there the R-Value of 30 mm with aluminium PUR Foam was given as 1.2

and this U-Value (thermal transmittance) seems to be quite important as well
http://en.wikipedia.org/wiki/Thermal_transmittance

[schuimpge]

http://www.sprayfoams.info/foam/the-r-value-myth/

Oil, check that page...it's a nice article about R-values.
Overall, spray foam is generally acknowledged as the best isolating material.
On top of that, it seals, strengthens, critters don't like it, silences rain noise..burglar proof..
There's simply nothing else that does all that. It's an investment that will increase the value of your property, plain and simple..

[oil]

http://www.sprayfoams.info/foam/the-r-value-myth/

Oil, check that page...it's a nice article about R-values.
Overall, spray foam is generally acknowledged as the best isolating material.
On top of that, it seals, strengthens, critters don't like it, silences rain noise..burglar proof..
There's simply nothing else that does all that. It's an investment that will increase the value of your property, plain and simple..

very intersting reading, thx

[Makmak456]

I had spray PU done to my roof, and at say 2 pm on a sunny day I can be under my roof and it is ambiet temp not 20+ C ................

[Makmak456]

that would be 20 c over air temp