Siliconised paint
Siliconised paint, also called silicone resin paint, is a facade paint based on a silicone resin emulsion. It repels rainwater while still allowing moisture from within the wall to escape as water vapour. That combination makes it suitable for mineral surfaces such as stucco, concrete and brickwork. It is not used on woodwork.
The paint forms a microporous layer. A raindrop is too large to enter those pores and runs off the wall. A water molecule in vapour form is far smaller and passes straight through. Water stays out, moisture gets out. Read more about vapour-permeable paint and the Sd value.
One important limitation: if a dense, old acrylic coating is already on the wall, this advantage disappears, because the layer underneath still traps the moisture. Siliconised paint is also less flexible than acrylic, so it bridges hairline cracks less well. Ask a professional to assess whether it suits your facade.
