I'd like to paint my pebbledashed house , it's cement based render, with spar stones (sharp edges). Please tell me your best/worse experiences? I am considering either a good wash with a stiff brush and water , then a fungicide/primer , then Dulux Weathershield or Sandtex?
Or: jetwash , a diluted coat of Weathershield , then a neat topcoat.
Is a primer essential? ANd rollers,brushes, or a spraygun?
This is a coastal location.
"......a good wash with a stiff brush and water , then a fungicide/primer , then Dulux Weathershield or Sandtex?"
Be aware that you will loose some of the stones when cleaning - it happens.
I only use a fungicide where it's obvious it's going to need it. For example right up under the soffits there won't be any exposure.
Spray gun is far too messy for this type of surface as you have to make sure that the paint goes all round the individual stones otherwise it will look as if it's full of holes when you've finished. The preparation and clearing up after spraying just takes too long and if you are in a coastal location the wind factor mitigates against using a spray.
Smooth render can easily be done with a roller as can pebbledash if it's been painted previously. Unpainted will shred the roller to bits (mind you won't help a brush either). A brush allows you work the paint into all the little nooks and crannies.
You'll use at least 1.5 x - 2 x the amount of paint for the first coat you'll think compared with a smooth render and I recommend two coats in any event.
Don't be surprised if rust marks appear after the first coat. This is caused by ferrous deposits in the sandused for the original render. This is dealt with by a quick coat of spirit based gloss paint over rust marks. Allow to dry and repaint with your masonry paint.
Another thing to watch out for is that painting it MAY mean you get some damp marks or black mould INSIDE. This is because the paint will be selaing the outside and any residual moisture in the render or the brickwork only has one way to go - inwards. This is not certain but be aware that it could happen.
Thanks for the reply: On the question of damp spots appearing inside , if I was to use a paint that allows "breathing" ? would that relieve the moisture trapping?
ALso , the rendered walls are 60-65cm thick stone , and dry lined with an existing air gap of approx 10cm. I have inspected the inside of the walls beind the lining where poss , and it's good , no sign of moisture so far , I feel that the existing air gap allows theany tmoisture to be pass up and out into the roof , thereby vented to open air. This is an old house , but the original timbers are very sound , we belive due to this airflow up through the walls and roof.
There are some damp spots already though ,all next to anything added to the original house , like UPVC windows , doors , and skylights......
So..... do you think we would actually be worsenning the existing situation by painting ?
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