Roof painting for cooling

[Francesco]

I am exploring roof painting to cool the house instead of refrigeration as the first option. My house has a flat iron roof of Klip-lok Hi-ten. There are specialised paints, eg SolarCool, NXT Cool Zone and Shield Coat that have high heat reflectance characteristics. Some studies have given roof painting credibility for reducing temperatures inside the house by 5-7 degree C.

Has anyone tried roof painting for heat reduction purpose? Thanks.

F

 

[John J]

Hi Francesco,

You say that you have Klip-lok roofing at the moment. Does this have a colourbond finish? If not and it is just a plain zincalume finish this is pretty good at reflecting heat. The 5-7 degree C may be true if changing from a dark colour.

Cheers

John

 

[Francesco]

Hi John J

I have not looked at the roof, but based on plans, it is just plain zincalume. The specialist paint I mentioned have much reflectance property with stark differences. The blurb of the paint companies make claim such as roof with paint can be handled by hand, whereas without paint will be too hot to handle.

A pity not too many resi roofs are applied with specialist paints based on the sparcity of comments on this issue. I understand the specialist paints are more usually specified for industrial and commercial metal roofing.

F

 

[George]

As to metal anything, we can have a quick check at any car park during sunny day.

When I touched white car, was hot, but metallic or darker colour car was like a furnace.
Suppose the same applies to roof and walls too.
Only problem to make it stick and last long enough to pay for itself.

I read report that Australia doesn’t use enough white/light colours for the climate.

 

[pantotango]

My partner is a painter and has used Resene Cool paint on a tile roof a couple of times and has said both times that he has noticed the difference when he has come to paint the interior and is up cutting in the temp is alot lower than it had been. Apparenty he just said to note that with that product the darker the colour the better it will work. He said he was suprised at how good it was. Not sure with tin as the ones he has done have both been tiles.

 

[BoatBoy]

Did a new roof on an IP not that long ago and shiny silver is the coolest say's the plumber using the melting Dunlop Volley test.

Spend some extra $$$ on higher R vale insulation.

Just put R3.3 in our PPOR and it knocked at least 6-7 oC off temp.

It's only 32.5 oC inside at midday now.

BB

 

[lizzie]

Apparenty he just said to note that with that product the darker the colour the better it will work.

do you mean, by this comment, that a charcol colour would be cooler than a light silver colour? if so, very interesting as the darker colours are favoured atm.

 

[sailor]

do you mean, by this comment, that a charcol colour would be cooler than a light silver colour? if so, very interesting as the darker colours are favoured atm.

I wouldn't think that was possible...tis against the laws of physics!

 

[George]

Dark colour items absorb and radiate heat better than light colour ones.

Ideal solution could be chameleon type paint, that in summer would turn white during the day and black at night, other way around in winter, but we might have to wait for that for quite a while.

 

[Peter 14.7]

I dont know about painting to save heat. Zincalume is very good at reflecting. Usually the darker colour is worst.

Suggest you consider batts at the ceiling and roof vents with inlet grills at the eaves. YOu can get solar roof vents that obviously work best when hot and pull an amazing amount of air which means the roof temp will be the same as the ambient temp instead of hot hot hot!

Note: Klip-lok roofing is specially designed to be laid flat and leak free. As such your roof may be very flat and any penetration such as roof vents may leak. Consider this.

Also assuming it is flat that strenthens the case for ventilation and batts as you have less air to heat before it starts to seep into the house.

Peter 14.7

 

[George]

False roof could be considered too.

I saw pictures of roof with 60 cm layer of soil and grass with plants on it. Unfortunately this has to be considered in planning stage of the house, as considerable loading must be taken into account.

Probably not appropriate to mention it here

 

[Francesco]

Thanks Peter14.7 for suggestion about solar vent, but flat roof is a problem. I understand it is not conduction or convection heat that is the main problem. It is the radiant heat from the ceiling to the room below. There should have been a foil below the batts to reduce the radiant heat transmission downwards.

Yes, George I did think about false roof. Not the soil and grass type, but maybe a UV-treated tarpaulin type of shade stretched out and held over the metal roof. The shade will capture the heat and wind blowing below it can dissipate the heat. Has anyone seen this done commercially? I believe in Singapore, a false concrete roof is built over the roof of high rise buildings. The result is that the highest units are so cold that condensation often happens.

 

[George]

Shade cloth best if not tightly woven, which will not act as sail in high wind situation.
Most air will be sucked through.

I wander if there is a company that specialises in false roofs.

With amount of sunshine this could be more environmentally friendly solution, as opposed to AC.

 

[thomop]

hi there, My name is Phil Thomson from Guardian Roofing here in Melbourne.
Nxt Cool Zone and Sheild Coat are not bad products. We have introduced some overseas products which work very well and are slightly more cost effective.

They will soon be availible to Aussie roof restoration companies.

For more info, visit www.guardianroofing.com.au
Regards

 

[thomop]

I forgot to mention, we are adding much more content to this site in the comming week.
Stay tuned for the products we will have on show case.
Also, please enquire if you are looking for a cooling option for flat deck tin roofs, and cement tiled roofs as we specialise in barrier heat reflective painting.

regards,

Phil
www.guardianroofing.com.au

 

[marg4000]

Friends had their factory's roof painted in one of the insulation paints.
Said it reduced temperatures indoors quite noticeably.
Marg

 

[exstatic]

hi there, My name is Phil Thomson from Guardian Roofing here in Melbourne.
Nxt Cool Zone and Sheild Coat are not bad products. We have introduced some overseas products which work very well and are slightly more cost effective.

They will soon be availible to Aussie roof restoration companies.

For more info, visit www.guardianroofing.com.au
Regards

I can also vouch for Phils work.. I have used him for one of my properties and couldn't be happier with the results.

Good to see you on here Phil

 

[Francesco]

I can also vouch for Phils work.. I have used him for one of my properties and couldn't be happier with the results.

Good to see you on here Phil

Any details about where to look for the paint and service in Canberra? Can it be DIY for flat metal roof?

 

[clubbie]

I am exploring roof painting to cool the house instead of refrigeration as the first option. My house has a flat iron roof of Klip-lok Hi-ten. There are specialised paints, eg SolarCool, NXT Cool Zone and Shield Coat that have high heat reflectance characteristics. Some studies have given roof painting credibility for reducing temperatures inside the house by 5-7 degree C.

Has anyone tried roof painting for heat reduction purpose? Thanks.

F

Yes it does work well on surfaces that radiate the heat from the roof through to the ceiling. But there is a easier way to reduce the UV heat transfer. Put a layer of foil insulation under the gal roof, you only need a 50mm gap. The foil will re radiate the heat. Cheaper and when the fiasco with insulation is sorted you will probably get most of the money back.

As for roof vents they are nice if you are living in your roof.

 

[AlmostBob]

most roofs already have soffit vents
a vent in the peak lets warm air out
when coupled with clubbie's described foil barrier and air gap, makes a chimney effect inside the roof and keeps ceiling spaces much cooler
my notes are long gone,
when I renovated a house in Cheltenham vic was a local paper ad, hired as a carpenter to make the light tunnels for the skylights, he made sure the foil barrier was continuous at the peak so that air had to run out the vent
air movement on a hot day felt like a fan was running