The covered area has been up quite a few years now. It has suffered from mould which is worse towards the front. This is the second time we have attempted to remove the mould. Been using a mixture of bleach and white vinegar and washing off with a pressure washer. The pressure washer alone won’t touch the mould even when threatened by Mrs J.

 

I don’t know what paint was used by the installer … maybe it was water based.

 

I propose to use an oil based high gloss paint.

 

Has anyone got any better suggestions….thank you

4 hours ago, JAS21 said:

Has anyone got any better suggestions….thank you

Try rubbing with a sponge and soapy water.

18 hours ago, stubuzz said:

Try rubbing with a sponge and soapy water.

I’m actually asking what paint and paint preparation to use, but thank you for your suggestion

6 hours ago, JAS21 said:

I’m actually asking what paint and paint preparation to use

Ok, Trisodium phosphate (TSP) in warm water applied with a sponge will prepare the area for painting. Give a final rinse with clean water. You an buy TSP on Shopee or Lazada. 

How about putting a metal plate over the molding surface ? Or tiles maybe ? the swimming pool grade types...

17 minutes ago, SingAPorn said:

How about putting a metal plate over the molding surface ? Or tiles maybe ? the swimming pool grade types...

The mould will only be underneath it if you tile  it

 

You need to clean it then buy a anti mould paint from the hardware store there's a ton of them...I used them all at one stage on my bathroom ceiling 

 

On 11/15/2025 at 7:32 PM, SingAPorn said:

How about putting a metal plate over the molding surface ? Or tiles maybe ? the swimming pool grade types...

Thailand that steel work could be a good idea …

Yes. Get a very high powered pressure washer and it'll blow the mold right off. You can then use a paint that has antifungal qualities and will help to prevent the mold from reestablishing itself. 

Exterior paints have anti fungal ingredients already mixed in.  What you want to do is clean it well.  Use a good quality primer TOA RUST TECH A + B Metal seems to be popular with good reviews.   Try not to paint in direct sunlight or paint in early morning, later afternoon to allow it to cure normally.

 

Then top with good quality Exterior Paint.

Don't know if available in Thailand, but you can get mould resistant paints.

I wouldn't use oil based paint, a good acrylic, water based enamel is better. You can use a primer/underpaint before the final layer(s) of acrylic paint. That will make it work with whatever paint has been used before.

 

For my white outdoor steel I use TOA Super Shield, but that only comes as semi gloss. TOA has a similar high gloss Super Shield called Aqua Gloss. I'm using it for my white doors. Not all building markets might however have Aqua Gloss it in stock.

 

TOA also has a mold and algae removal, it's called TOA Microkill 113, and is available in building markets like HomePro.

I think you have to browse in DIY shops and then start from blank concrete.

I see the disturbing pic of washing off bleach and vinegar, you are aware both are not good for eyes and inhalation? Also not for skin, but ok maybe less effect, but...

Vinegar is acid and can also react with bleach, mild reaction and you could have chloride released. form bleach Sodiumhypochloride.

No fun, but put on vinyl suite with overal eyes safety goggle. But up to you to decide.

23 hours ago, spidermike007 said:

Yes. Get a very high powered pressure washer and it'll blow the mold right off. You can then use a paint that has antifungal qualities and will help to prevent the mold from reestablishing itself. 

Ditto + you need to get that nozzle really close for it to be effective within 4 inches with the most aggressive nozzle you have.you will create a lot of work to prep and paint with a mold resistant paint.that should work just be prepared for a lot of prep work and paint!!perhaps do one area at a time.good luck and don’t fall off the ladder!!