Painting Exterior Walls

southernsun

Hi,

We are painting the whole of the outside of our end of terrace house (early 1900's) which consists of brick at front/back, old render on side with a small extension and conservatory which is also rendered (newer than main part of house). This is to try and solve a penetrating damp issue and also to improve the look of the house.

We have purchased Sandtex masonry paint, Sandtex stabilising solution and Thompson waterseal and had planned to put a coat of waterseal on first followed by a coat of stabilising solution and 3 coats of paint.

Having tried this at the weekend on a small section of the newer rendered wall the waterseal stopped the stabalising solution from being applied (just ran off wall). Obviously good as means water seal is working.

My questions are:

Would applying the stabilising solution first work?

Could it be that the newer render just didn't need the stabilising solution and if I did the same to the older render and bricks it would go on ok?

Would I get away with not applying the stabilising solution at all?

Thanks in advance for any help.

societys_child

to put a coat of waterseal on first

Seem to remember (it's a long time ago) but I'm sure it warned that the waterseal should be the final coat. Think it's silicone based and paint (or stabiliser) probably wont stick too well. Having said that, I don't think you'd need sealer over the masonry paint?
You normally only need stabiliser if the render is flaky

southernsun

Thanks for the reply. Spent last hour on phone to various companies all who have given different advice/warnings.

Thompson said on phone that it is not possible to use waterseal and masonry paint together as the waterseal would stop paint going on but the product sheet says to allow 2-3 days before applying oil based paint and 30 days for waterbased paint which to me would imply you can paint over it. I assume Sandtex is water based masonry paint?

Bostix who make Wickes water seal said apply waterseal and wait 6 weeks for surface to weather and then apply masonry paint and it should go on fine, basically throw a cup of water at it and if it doesn't bead on surface then you can paint it.

So confused now, all I want is a waterproof barrier to stop water penetrating house and a nice looking finish to the exterior.

I applied the Wickes water seal I already had to the newer render (still about 6 years old) on our conservatory and 24 hours later tried to apply a stabaliser which just ran off, I then applied a coat of masonry paint and it went on fine and is still looking fine. Not sure if this means it will be ok if its stayed on or whether there will be a problem further down the line. The impression I have got so far is the reason you cant paint over waterseal is because it would repel the paint but that hasn't been the case so far.

DaftyDuck

I've just painted the top half of our five bedroom house, horrible lumpy render. Serious arm-ache as a result.

I really don't believe you need water seal as well as masonry paint. My house is right on the east coast seaside, so gets lashed. I did give 3 coats (two recommended on the tin) of masonry, and that's made a near-perfect coat. My render is 100 years old, and in reasonable nick, given the exposure.

I certainly don't see the need for waterseal as well. I would be fairly sure it's more likely to degrade the adhesion of the masonry paint and reduce the overall barrier to moisture.

Stabiliser might be needed for a crumbly surface, but I rubbed mine down vigorously, and that seemed to do the trick.

societys_child

Sounds like all the advice youve been given is what I was thinking.

all I want is a waterproof barrier to stop water penetrating house and a nice looking finish to the exterior

Sandtex should do this ok - designed to protect from the elements but allow the substrate to breathe.

southernsun

Thanks again for the replies. After reading them and taking 10 minutes with a coffee to reflect I think I now know the best thing to do and that is drop the water seal completely.

Sounds like it is an unnecessary cost if the masonry paint will act as the waterproof barrier and we have already purchased enough paint to do 3 coats.

Thanks again for all the help and replies.