I plan to repaint this external door which suffers from I take to be mildew. Any recommendations for what to use so that this problem does not return?  Any anti fungal gloss paints available in Thailand?

Mildew and fungus can be deadly serious to anyone health, they can make you so sick it's beyond belief, better check the rest of the house thoroughly for rote, mildew and fungus, i would advise to throw away the door all together and get a new new unless you will strip it to the base wood and even than it is 100% you got all the mildew out...

Spray a 5% solution of copper sulphate on the mildew, and allow to stand for 48 hours. Then hose the door off, and clean with steel wool. Hose off again. Once dry, the door can be repainted. The mildew wont be coming back.

My wife wants to replace the door with  non wood material. If we repaint even after cleaning thoroughly I am sure the mildew will return. That's why I am looking for an anti fungal paint.

2 hours ago, pj123 said:

Any anti fungal gloss paints available in Thailand?

Yes, reading the cans will help.

Found this primer on HomePro but according to TOA its for brick and concrete.

https://www.homepro.co.th/p/1153447

 

Fungus need food to grow. Dust/dirt in the air sticks to door and fungus has a place to live. Cleaning often will stop fungus growth. Hot moist climate and dirt in air is the main problem. Some paints (and maybe some plastic doors) have anti-fungus chemicals in them and reduce growth. A glossy paint will make it easier to keep doors clean.

 

Is that wood door? Looks like it is rotting inside.