Cleaning Rendered Walls

[fartingspartan]

Hi, I decided to give windows a clean lazily using the hose from ground level.... managed to hit wood above windows.. sending sludge water down onto render... staining it which I'm now getting grief about...

Any ideas how best to clean it - have ladder I can use to get to it to spray chemicals or cleaner onto it.

Have tried just more water and a brush but no joy.

https://ibb.co/1XdxkHh

 

[dave28]

very very gentle with a pressure washer maybe.

the chemical i use on my walls is called hypochlorite but its very strong stuff and i dont know if its safe on that type of wall.
i use it on roughcast and patio slabs etc etc....

 

[norm]

Is it actually stained or is that the residue sat on the surface?

I would try going over it with a stiff brush and water. It's not a good idea to use a pressure washer on render ever as it can cause pitting.

If that doesn't work, ordinary household bleach will do it, but you'll have to test it first on an inconspicuous area first.

 

[kinetic747]

Is that a coloured or painted render? If you can't wash the stain out I'd be tempted to paint over it as long as you can get a colour match.

 

[Bluecube]

very very gentle with a pressure washer maybe.

the chemical i use on my walls is called hypochlorite but its very strong stuff and i dont know if its safe on that type of wall.
i use it on roughcast and patio slabs etc etc....

Sodium Hypochlorite is bleach. In diluted form (5%) it’ll be ok to use on render. Sounds as if the OP has dislodged muck onto the render so hypo is a huge overkill particularly as the whole wall will have to be treated otherwise you’ll end up with different coloured patches.

I’m surprised the muck won’t move under hose pressure. If it’s just a small patch then paint over it.

PS unless you live in a soft water area, spraying your windows will water will cause a lot of streaks.