Cooling rooftop paint

pissontheroof · Post by **pissontheroof** » Fri May 19, 2023 5:41 am

Install foil backed insulation board under the roof .
Put it in the attic or just glue it up to the ceiling

Gary Small · Post by **Gary Small** » Fri May 19, 2023 6:31 am

Jerry Atrick wrote: ↑Wed May 17, 2023 6:18 pm
ali baba wrote: ↑Wed May 17, 2023 5:29 pm I've seen news reports about special paints that are highly reflective and can make your roof much cooler. Are they available in Cambodia?
Yeah, it's the stuff they paint felt sealed rooves with

But any silver paint would be a help

Flat white paint is cheaper and more reflective.

beaker · Post by **beaker** » Fri May 19, 2023 6:59 am

Kammekor wrote: ↑Thu May 18, 2023 3:18 pm
beaker wrote: ↑Thu May 18, 2023 2:20 pm I think a better solution would be to add an insulation layer on top of the metal sheeting. I would install the traditional "grass" style roof ,as used in countryside, over the metal roof. That would block any radiated heat from the sun.
A 'grass style roof' will be a challenge in both the dry season and the rainy season, I reckon. Anyone experience with it?

I have experience, I lived in a great old bamboo house with grass roof in with grass roof in Thailand. Rented for several months at the bargain price of 100 baht ($3.30) a month. Also while our home was being upgraded we built a bamboo w/grass roof hut on the property it was 5 X 5 meters and the price of bamboo, woven mats for sides and grass roof was ~$100. Lived in it for 5 months then used it for utility/storage for years with no leaks or problems.
I'm sure this type of roof would out last the paint, stop radiated heat from the sun 100% and be cost effective. There should be no problem or concerns about water tightness as it is being laid over the existing metal roof. The grass roofing comes in "panels" wrapped around small bamboo sticks and are laid/tied in overlapping rows much like shingles. I also like the thatched roof looks

Kammekor · Post by **Kammekor** » Fri May 19, 2023 8:00 am

beaker wrote: ↑Fri May 19, 2023 6:59 am
Kammekor wrote: ↑Thu May 18, 2023 3:18 pm
beaker wrote: ↑Thu May 18, 2023 2:20 pm I think a better solution would be to add an insulation layer on top of the metal sheeting. I would install the traditional "grass" style roof ,as used in countryside, over the metal roof. That would block any radiated heat from the sun.
A 'grass style roof' will be a challenge in both the dry season and the rainy season, I reckon. Anyone experience with it?
I have experience, I lived in a great old bamboo house with grass roof in with grass roof in Thailand. Rented for several months at the bargain price of 100 baht ($3.30) a month. Also while our home was being upgraded we built a bamboo w/grass roof hut on the property it was 5 X 5 meters and the price of bamboo, woven mats for sides and grass roof was ~$100. Lived in it for 5 months then used it for utility/storage for years with no leaks or problems.
I'm sure this type of roof would out last the paint, stop radiated heat from the sun 100% and be cost effective. There should be no problem or concerns about water tightness as it is being laid over the existing metal roof. The grass roofing comes in "panels" wrapped around small bamboo sticks and are laid/tied in overlapping rows much like shingles. I also like the thatched roof looks

Sounds good.

Did you have to anything to keep it 'alive' during the dry season?

armchairlawyer · Post by **armchairlawyer** » Fri May 19, 2023 11:26 am

Re the bricks in the wall getting hot. Has anyone used AAC blocks instead of bricks?

https://pklightblock.com/

yong · Post by **yong** » Fri May 19, 2023 7:00 pm

From a person who had been in the roofing market since 1997 nothing beats having fibreglass wool under the metalsheet roof or any roofing material for that matter.

On a sunny day with an outdoor temperature of say 35 degC the metal surface could be around 80 degC. If you ask me how I know I have gone up a roof to measure the temperature myself countless times and even installed temperature loggers for long term monitoring roof surface temperatures for a stretch of over 6 months (I still have the data) and average day temperature is around 55 degC. What I’m trying to say even if any good coating were to bring temperature down 10 degC (which is almost unheard of) you still end up with around 45 degC. This really makes the coating a waste of effort.

So the best bet that will surely work is mechanical insulation like fibreglass wool rather than coatings.

Before I go I like to make one last point. “Screws”. Sorry for being a little long winded. Let’s say you selected a good metalsheet like AZ100 for your roof that provides you 10 years warranty. Unknown to the owner he may choose to use normal zinc plated screws for installation as he feels that more importantly is the quality of the roofing sheet.

Let’s do the maths - roofing sheet with installation costs 200 baht per sqm (without insulation) ; screws needed per sqm is 3-4 pcs let’s assume 3 pcs and each zinc plated screw costs 0.6 baht total is 1.8 baht now each coated screw is 1 baht total is 3 baht for a screw that gives 10 years warranty.

Cost of screw using coated screw suddenly skyrocket by bloody 67% this is ridiculous and totally unacceptable. However total cost per sqm goes up from 200 to 203 baht which is only 1.5% a minuscule 1.5% but what you get is:

1. For 10 years you don’t get leaking roof due to rusted screws which cause lots of disruptions

2. You don’t get stains from rusted screws

3. If your zinc plated screws rusted and caused corrosion to your metalsheet roof your roof sheet 10 years warranty will be void immediately.

4. Screws is the smallest element in your entire roof system and the weakest link, screw fails roof fails.

I could go on and on and on.

from a humble screw salesman

truffledog · Post by **truffledog** » Fri May 19, 2023 7:27 pm

yong wrote: ↑Fri May 19, 2023 7:00 pm From a person who had been in the roofing market since 1997 nothing beats having fibreglass wool under the metalsheet roof or any roofing material for that matter.

On a sunny day with an outdoor temperature of say 35 degC the metal surface could be around 80 degC. If you ask me how I know I have gone up a roof to measure the temperature myself countless times and even installed temperature loggers for long term monitoring roof surface temperatures for a stretch of over 6 months (I still have the data) and average day temperature is around 55 degC. What I’m trying to say even if any good coating were to bring temperature down 10 degC (which is almost unheard of) you still end up with around 45 degC. This really makes the coating a waste of effort.

So the best bet that will surely work is mechanical insulation like fibreglass wool rather than coatings.

Before I go I like to make one last point. “Screws”. Sorry for being a little long winded. Let’s say you selected a good metalsheet like AZ100 for your roof that provides you 10 years warranty. Unknown to the owner he may choose to use normal zinc plated screws for installation as he feels that more importantly is the quality of the roofing sheet.

Let’s do the maths - roofing sheet with installation costs 200 baht per sqm (without insulation) ; screws needed per sqm is 3-4 pcs let’s assume 3 pcs and each zinc plated screw costs 0.6 baht total is 1.8 baht now each coated screw is 1 baht total is 3 baht for a screw that gives 10 years warranty.

Cost of screw using coated screw suddenly skyrocket by bloody 67% this is ridiculous and totally unacceptable. However total cost per sqm goes up from 200 to 203 baht which is only 1.5% a minuscule 1.5% but what you get is:

1. For 10 years you don’t get leaking roof due to rusted screws which cause lots of disruptions

2. You don’t get stains from rusted screws

3. If your zinc plated screws rusted and caused corrosion to your metalsheet roof your roof sheet 10 years warranty will be void immediately.

4. Screws is the smallest element in your entire roof system and the weakest link, screw fails roof fails.

I could go on and on and on.

from a humble screw salesman

I completely agree on the fibreglass insulation. But I cant understand why you would use a metalsheet as top layer as it gets VERY hot even coated with a magic heatabsorbing paint. The sure is a better alternative which does not blow the budget.

ressl · Post by **ressl** » Fri May 19, 2023 8:02 pm

yong wrote: ↑Fri May 19, 2023 7:00 pm Before I go I like to make one last point. “Screws”.

How about stainless steel? I have been driving a Defender for more than a decade, I don't trust coated/painted screws any more...

And in the context of this topic: the safari roof (sandwhich roof of steel, air, steel) works miracles

yong · Post by **yong** » Fri May 19, 2023 10:36 pm

ressl wrote: ↑Fri May 19, 2023 8:02 pm
yong wrote: ↑Fri May 19, 2023 7:00 pm Before I go I like to make one last point. “Screws”.
How about stainless steel? I have been driving a Defender for more than a decade, I don't trust coated/painted screws any more...

And in the context of this topic: the safari roof (sandwhich roof of steel, air, steel) works miracles

Stainless Steel

a. Not all stainless steel are the same so if application is outdoor or exposed to the elements please use only 300 series like 305. 400 series like the most popular 410 will rust as a matter of fact it rusts very quickly when it’s exposed to the elements. 410 screws are used for indoor and great with furnitures.

b. Stainless steel is excellent with non-ferrous metals and not recommended to be use with normal steel especially roofing sheets made with carbon steel. The reason is the phenomenal known as bi-metallic corrosion the arise from dissimilar metals causing the weaker material to corrode faster than it should be.

Sandwich Panels

I do agree that the sandwich material you suggested works as air is a bad conductor.

Post by **Username Taken** » Sat May 20, 2023 4:19 am

And......., what if the OP is talking about a standard PP brick/cement building with a flat concrete roof?

Cooling rooftop paint

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