Lower electricity bill by painting roof like the Greeks do in Santorini

[4myr]

Hi, I was wondering, have anyone done this experiment in Thailand before?

 

Paint your roof with lime wash, a mixture of hydrated lime, water, linseed oil [for waterproofing] and table salt [for durability].

I have a corrugated  fibre cement roof with a lot of heat mass, which keeps my attic space between 45-65C and my ceiling at 38-39C on a hot day [32-35C].

My roof rafts and truss is made from steel and conducts & radiates the roof heat and transfers it to the inner walls as well.

 

I have been considering insulation options like spray PU foam [against roof in attic space] or mineral wool insulation [attic floor], however this painting method is more friendly to human, environment [where I live the soil is acidic] and my pocket.

 

The temperature effect as shown in below YT video is dramatic [around 20C temp decrease in attic space]. Unfortunately in a moderate climate with lower ambient temp and where the sun does not shine as hot. I would be happy if the attic floor temp can be lowered to 30-35C and the inner walls 1-2C above ambient temperature.

 

I estimate the paint price to be around 7B per m2 for 2 coatings. Normal roof paint costs around 35B / m2. I can't find a price for a ceramic based roof paint, which will reflect the sun much better than ordinary roof paint or lime wash, but assume it is much more expensive.

I will need to hire someone to go on the roof to [re-]do the paint job and remove the dirt on the white paint on a regular basis.

 

Any thoughts on how more often I need to repaint lime wash vs repainting using a synthetic roof paint, which I supposed is more waterproof and more durable.

 

Here some links about this subject:

 

Hydrated Lime as a Highly Reflective Roof Coating for Home Cooling

How much can painting a roof white reduce its temperature?

 

[Kwasaki]

Vent the roof and eaves then put rolls of fibreglass wrapped in silver wrapping on your ceiling area the thicker the better.

Job done.

 

Windows, walls may need attention with shaded. 

[sometimewoodworker]

If you are keen on a DIY job then spray on barium sulfate, you will need about 30 very thin coats but you will then have the most reflective (to heat) surface possible. The material is not expensive, but the process is rather laborious 

 

[h90]

On 5/11/2023 at 5:19 PM, Kwasaki said:

Vent the roof and eaves then put rolls of fibreglass wrapped in silver wrapping on your ceiling area the thicker the better.

Job done.

 

Windows, walls may need attention with shaded. 

That works very well....only the silver wrapping went to dust...it is aluminum foil that corroded.....when you go up the roof you can't breath so much fibers in the air.

[h90]

Just now, h90 said:

That works very well....only the silver wrapping went to dust...it is aluminum foil that corroded.....when you go up the roof (the room between roof and ceiling) you can't breath so much fibers in the air.

 

[Kwasaki]

2 hours ago, h90 said:

That works very well....only the silver wrapping went to dust...it is aluminum foil that corroded.....when you go up the roof you can't breath so much fibers in the air.

16 years on my foiled covered fibreglass is in tact. 

[dinga]

On 5/13/2023 at 4:34 PM, Kwasaki said:

16 years on my foiled covered fibreglass is in tact. 

Be glad you don't have a rodent problem (my b*ggers are very happy to chew the batts) 

[Kwasaki]

1 hour ago, dinga said:

Be glad you don't have a rodent problem (my b*ggers are very happy to chew the batts) 

Do something about it, easily done. 

I have no problem in my village. 

[dinga]

7 minutes ago, Kwasaki said:

Do something about it, easily done. 

I have no problem in my village. 

Hard to imagine someone NOT to "do something about it".  Am using traps to secure and relocate the little b*ggers (since killing them is not an option...)

 

Delighted if you have 'something' that addresses the problem

 

 

[Kwasaki]

10 minutes ago, dinga said:

Hard to imagine someone NOT to "do something about it".  Am using traps to secure and relocate the little b*ggers (since killing them is not an option...)

 

Delighted if you have 'something' that addresses the problem

 

 

What i mean is we don't have a problem with rodents. 

Stick some wild cats up in your loft. ????

My in-laws smoke out the the loft areas. 

[Crossy]

1 hour ago, dinga said:

Hard to imagine someone NOT to "do something about it".  Am using traps to secure and relocate the little b*ggers (since killing them is not an option...)

Just remember, rats "home": -

 

 

[BenStark]

1 hour ago, dinga said:

Hard to imagine someone NOT to "do something about it".  Am using traps to secure and relocate the little b*ggers (since killing them is not an option...)

 

Delighted if you have 'something' that addresses the problem

 

 

Why is killing not an option, do you consider them pets?

 

I have these in my loft, outside the house in covered drains, as well as on the ceilings from my roof overhangs, and I have no problem with rodents.

 

If occasionally some enter the loft, they are gone within a day. Available on Lazada, makro and tesco.

 

Flocoumafen

 

[sometimewoodworker]

13 minutes ago, BenStark said:

Why is killing not an option

The smell!

[Kwasaki]

3 minutes ago, sometimewoodworker said:

The smell!

Vented roof. ????

[sometimewoodworker]

7 minutes ago, Kwasaki said:

Vented roof. ????

So that not only you can enjoy the fragrant odour of death but all the surrounding people can have the pleasure!!!

[KannikaP]

5 minutes ago, sometimewoodworker said:

So that not only you can enjoy the fragrant odour of death but all the surrounding people can have the pleasure!!!

Do you mean that the neighbours a few hundred metres away could smell a dead rat after a week?

[KannikaP]

20 minutes ago, sometimewoodworker said:

The smell!

The body of a dead rat wiull be minimal and gone within days, dried up.

[sometimewoodworker]

14 minutes ago, KannikaP said:

The body of a dead rat wiull be minimal and gone within days, dried up.

You obviously haven’t come across our particularly large well fed versions!

[KannikaP]

10 minutes ago, sometimewoodworker said:

You obviously haven’t come across our particularly large well fed versions!

From where are they getting their food?

 

[sometimewoodworker]

1 hour ago, KannikaP said:

From where are they getting their food?

 

Take your pick.

[KannikaP]

2 minutes ago, sometimewoodworker said:

Take your pick.

I've got no rats in my place

[dinga]

2 hours ago, sometimewoodworker said:

The smell!

Funnily enough (given we live in Thailand), my wife is Buddhist and killing them is out of the question

 

[sometimewoodworker]

1 hour ago, dinga said:

Funnily enough (given we live in Thailand), my wife is Buddhist and killing them is out of the question

 

We don’t kill them ! We just feed them, then they decide to die!