32 minutes ago, Denim said:

Not going to make a huge difference but just another little push in the right direction.

And might turn out as the wrong direction in the end.

 

Lots of long term unknowns.

 

Continuous surface moisture effects on the paint layer under the hot Sun.

 

Effects of multiple thermal expansion/contraction cycles on the wall's structural layer (if not sprayed continuously).

 

Potential foundation over-saturation and related damage.

 

Just to name a few...

1 hour ago, gejohesch said:

forgetting to mention that the most important cooling factor is the evaporation process

Was what made me assume a rather less erudite education. Physics is a subject that has quite a few pitfalls for those who assume that an effect is of necessity caused by one thing when it’s really caused from something quite different.

3 hours ago, unheard said:

Lots of long term unknowns.

Agreed. Why I have not gone full steam ahead myself.  Experimenting for the first time due to the long period of high temperatures we have had. For a long term solution , correct to be concerned but over a two or three week period I'll try anything just to see for myself what the short and long term effects are or if it helps at all. As another poster said earlier , no one idea will prove a cure all.  Having tried everything I can think of it does seem that if you want to be really cool you have to bite the bullet and go for air con. Trouble is, from previous experience , once you have it you will use it and the electric bills go up a lot.

 

Example ....back in the cool season ( lol ) our electric bill was 500 plus baht. Just got my new bill for today after heavy use of the air con, 2500 baht !!! ( only one in the bedroom ) . The guy came to empty our septic tank today and was bitching about the heat. Turns out his electric bill was almost exactly the same as mine ...2500 plus. And he is Thai !!  What chance do I have ?

11 hours ago, unheard said:

And might turn out as the wrong direction in the end.

 

Lots of long term unknowns.

 

Continuous surface moisture effects on the paint layer under the hot Sun.

 

Effects of multiple thermal expansion/contraction cycles on the wall's structural layer (if not sprayed continuously).

 

Potential foundation over-saturation and related damage.

 

Just to name a few...

Good comments and caveats! However, when it comes to sprinkling water on top of the roof, what could really go wrong? Roofs are made to withstand repeated rain after all, no?

 

Sprinkling the roof has not come into my questioning so far, as I had the whole roof redesigned (I did the design myself, I am a bit of an amateur architect!), and that included : more space between the roof and the hanging ceiling for better ventilation + roofing sheets with insulation layers + insulation rolls laid over the hanging ceiling before closing again. That made a huge difference to the ambient temperature in the living space.

 

My problem now is (again) : the walls and especially the windows get hot and radiate a lot of heat inside of the house.

1 hour ago, gejohesch said:

My problem now is (again) : the walls and especially the windows get hot and radiate a lot of heat inside of the house.

This is a point to which you have been given several different options, if they are not acceptable please list the ones you don’t like/can’t do/can’t afford so that there is an opportunity to avoid those. Maybe others are available.

 

So far I haven’t seen that any are being adopted/going to be implemented already in use.