How do you handle the horrible looking dark mold that grows on the outside walls and walkways? Is there a paint which repells this? Thinking about buying a power washer but would like to know what has been proven to work first.

Go to YouTube and search for "pressure washer" how to's.  A lot depends on what surface, whether it's painted, raw wood, stone, cement. etc.  Also, whether it's horizontal or vertical.

 

I did a lot of pressure washing around my beach neighborhood in Galveston as a hobby when I was a Covid refugee.  I probably washed a dozen of my neighbor's homes, decks and (mostly) driveways just for fun.  I found out that it's possible to do more harm than good on the wrong surfaces and with the wrong technique. 

 

For painted surfaces, I'd suggest diluting swimming pool bleach (it's cheaper) with a little bit of surfactant (dish soap) and skip the pressure washer unless you want to risk stripping some of the paint off. 

 

If it's stone or cement, get after it with the pressure washer.  Use a disk if you can find one in Thailand (good luck with that) and your pressure washer is powerful enough to drive one.  You need at least 2.5 GPM at 3000 PSI for the disk and most household units won't do that.

 

 

There's something cathartic for me about pressure washing a driveway using a gas powered pressure washer with a disk.  I posted a few of my driveways to YouTube, but they're not public domain and I can't access YouTube from China here to get the links.  But that's not important because there's so many better ones out there, with narration to help noobs like us.

 

2 hours ago, bhatmasterson said:

How do you handle the horrible looking dark mold that grows

I've noticed lots of dark mould at the base of the heating unit at the sauna I go to. 

 

A concoction of bleach vinegar and baking soda will annihilate it. Then paint over it with something slick like two-part epoxy paint.

Thanks for the suggestions. I will post some photos tomorrow so you can see what I'm up against. If I can find a solution that works the wife can start a business. Every house on every street in the neighborhood (Moo Bann) has this unsightly problem. All over Chiang Mai really.
I have a compressor so I guess I'll be looking for a pressure washer that I can hook up to it. 

This is the eyesore on practically very property. 

Fighting against nature.......

20 hours ago, bhatmasterson said:

This is the eyesore on practically very property. 

Clean as recommended above. Repaint and mix zinc oxide in the paint to inhibit the reoccurrence of the mold, the smoother the paint surface the easier it is to clean. Clean the concrete then soak the concrete with copper sulfate added to the water to inhibit the mold. Mix copper sulfate and zinc oxide into the concrete mixture next time before laying concrete.

Thanks for the recommendations!

 

Where does one buy zinc oxide and copper sulfate?

3 hours ago, MrBrad said:

Where does one buy zinc oxide and copper sulfate?

 

Both on sale through  Lazada online store.

On 11/13/2025 at 11:26 AM, quake said:

 

Both on sale through  Lazada online store.

or: 

World Chemical,
Pa Daet 261/3-6, Mahidol Road, Pa Daet Subdistrict, Mueang Chiang Mai District, Chiang Mai 50100, Thailand
Chiang Mai Municipality, Chiang Mai Province, 50100
Get directions

telephone: 053 204 446