Rendering block wall??

eas

Hi all

we're in the middle of a garden renovation. One extra job that has come up is rendering a souround wall. The wall is made up with blocks, and had been painted with masonary paint (about 5 years ago)

My question is around the painted surface. One builder is saying he would have to pressure wash the walls to remove the paint before applying the render, the other says this idea is crazy and a waste of time.

Can anyone let me know if the paint needs to be removed before applying a cement rendering?

Thanks for the advice.

cheers

TKK

To my mind you'd have to pressure wash the wall first to clean off any dirt etc. in order to ensure that the render bonds properly.

eas

Hi TKK

Thanks for the reply.

I can see having to clean the wall first. But 20 mins with a yard brush & soap + water could do this.

The thing is the builder is suggesting he would need to remove the paint (one coat - clean, no peeling or flaking) from the wall for the render to adhere properly. That would will take much much longer. That's why I'm wonderg if it's actually needed.

hiscan

after washing the wall it should be unibonded and scudded before plastering then you will have no problems