Advice about painting exterior masonry

[rubble2]

Hi,

I am in the process of painting the house exterior and would appreciate some advice regards painting the stome window sills and surrounds.

We have had problems with the white masonary paint discolouring badly within a few months of application (see first picture). I have therefore decided to strip off the old masonry paint completely and start again - picture 2 shows the sill stripped.

First question is, do I need to prime the stonework in any way before applying new masonry paint? or do I just apply it straight on the bare sandstone?

Second question - what is the best product to use in order to fill any slight recesses in the stonework? would exterior Polyfilla be ok or do I need a special stone repair product?

Finally, in the third picture, you can see that the surface on some of the upright parts of the window surround have a grey rather than a sandstone appearance, does this need to treated any differently? or is it just that the stone has been painted for so long that the surface colour has altered in some way?

Thanks for any assistance you can provide

Picture 1

• rubble2
• 7 Aug 2011
• 1

Stained masonary

picture 2

• rubble2
• 7 Aug 2011
• 1

After stripping

picture 3

• rubble2
• 7 Aug 2011
• 1

Different colour?

 

[TheDec]

If your sills are sandstone you should remove as much if not all of the existing paintwork and apply a sealer/stabiliser before applying your masonry paint, with regard to fillers Toupret would be a good choice.

Dec

 

[ic1927]

Follow The Decs advice regarding stabilising the sandstone before painting. Using filler on masonry however can be risky, I've seen a lot of them eventually fail and blow, especially exterior polyfilla. You may be better off using a rapid set waterproof sand and cement mix, or mix sand and cement with some SBR, always finish it with a damp sponge NOT a filler knife as this will give the paint a better chance of sticking, if you rendered an exterior wall and finished it with a trowel, paint would not stay on it for long, that is why they fine it down with a sponge, gives the paint a better grip.