Problem with rising dump, external walls

I'm assuming, that the black stuff on the walls is a rising dump.

3 external walls have this problem, however 1 wall does not have this problem. Problematic walls are in a direct contact with a concrete (driveway, walkway). Non-problematic wall has a soil. I'm thinking, that the concrete is preventing wall breathing or the concrete is transferring moisture to the wall.

Bad wall.

Attachment 90928

Bad wall.

Attachment 90929

Good wall.
Attachment 90930

What I was thinking is dug up a trench around the house and fill it with rocks. I would not go full "french drain" with a pipe inside of it. Just a rocks between house and concrete. To let the wall breathe and let any water potential water drain quickly into lower levels.

Do you thing it would help?

Idea:

Attachment 90935

Hello

Do your external walls have visible, above concrete/slab level, damp proof membranes. To stop the moisture rising?

Not if its Thai built he won't. The question is whether the damp is inside or merely on the surface of the wall outside. From the OP it seems its just the usual splash off the surface and so his solution should do the trick.

Rising dump? Isn't it rising damp????

Something not quite right here.

Quote:

---

Originally Posted by nidhogg

Rising dump? Isn't it rising damp????

---

I can't believe my puns got deleted.

Cy must be a mod then. :)

Quote:

---

Originally Posted by malmomike77

Not if its Thai built he won't.

---

Looking at the bases of the external walls on the Thai house I live in and the gaps under them, I concur.

Quote:

---

Originally Posted by malmomike77

From the OP it seems its just the usual splash off the surface and so his solution should do the trick

---

I would suggest the inner walls being away from the external rain would not be as exposed to water collection under them.

Black mold is a common problem in humid tropical countries. Looked at some homes in Hilo Hawaii recently and they had mold from top to bottom as it rains so often there.

Your case is likely all the splashing off the ground keeping the wall wet. If you had more roof overhang, you likely would not have the issue. You might consider rain gutters to direct the water to downspouts.

Agree with above 100% . It is common and you need to get it to dry out. You can power wash the black mold off and repaint it with a good sealant. Do it during summer. Gutters appear to be only option.

Quote:

---

Originally Posted by Stumpy

Agree with above 100% . It is common and you need to get it to dry out. You can power wash the black mold off and repaint it with a good sealant. Do it during summer. Gutters appear to be only option.

---

Our house is four years old now, this year the black on the concrete paths and driveway was worse than last. Water blasted again, but that won't stop it long term.

Global House and Thai Watsadu have various antimold concrete treatments - welcome a recommendation.

Will the runoff of whatever chemical it is affect the gardens?

Don't want to solve one problem but kill off what's grown nicely.

might sound stupid but vinegar kills mould and should not cause any problems
its what you use to kill fungus in your fridge
paint it on when the wall is dry might work

Is the side that gets moldy the North side? or the side that gets the least sun?
Do you have gutters on that side?
Less moisture and or more sun is your solution.

Did you try scolding the offending wall by repeating the phrase "Bad wall. Bad wall" it works with my dogs. LOL