old external wall painting

[lemsip1]

Hi

We have just bought a house with rendered outside walls. These have never been painted, they must have been rendered 30 years ago or so. We are renovating the house and wish to paint the outside.

We have noticed that parts of the render appear a little darker on the house, which appears to be wet but is probably an algi or something as the weather is warm and the house has had time to dry recently.

Is their a solution that can be applied to the render to stabilize this problem or a preparation process that needs to be done before applying the first coat, which I would water down.

Thanks for any help in advance.

Andy

 

[kdLeeds]

I did a similar job a few years ago on previously unpainted render (pebbledash).

The technical people at Sandtex were very helpful with recommendations regarding loose render, algie, stabilisation etc.

Ring them, or look at their web site www.sandtex.co.uk

Keith

 

[Zampa]

Give it a pressure wash down first, that should remove the algae..unless the surafce is powedery and chalking then I wouldnt use a stabiliser on it...stabiliser neeeds to be able to soak into a surface.

I wouldnt actually use stabiliser in this situation anyway..id go for a masonry paint based on pliolite...thin the first coat, which will act as a sealer by15-20%...then apply two more...just slightly thin to make application easier