Painting over Thompson's Waterseal

[Endofmytethers]

Hi,

A quick question - I had coated the side wall of my house with Thompson's waterseal after it was re-pointed, thinking it was the old solvent based formula. I have subsequently discovered that it was actually the water based 'new improved formula' with silicone in it and it advises not to overpaint.

I do need to paint the wall as water is still coming through the brickwork, which I think is because of tiny cracks in the brick (and was planning to do at least 2/3 coats of sandtex masonry paint) - has anyone ever tried painting bricks with paint after applying the new 'improved formula' thompson's waterseal? does the paint come off? If so, what are my options? I do need to get the wall painted.

Thanks

 

[footprints]

I suspect your have gone a long way up a creek without a paddle

Those sort of coatings that shed water are not really designed to paint.

Thompsons has to be your first port of call, you MIGHT get away with a primer like Zinsser Bullseye 123 which is for difficult surfaces, but again before you put anything else on the wall speak to the makers.

Please post back how things go it would be nice to learn how you resolve it.

Kind of thinking it might be a hack off and re-render job but that's got to be the last resort.

Best wishes,
footprints

 

[ic1927]

How long has the waterseal been on the wall? In my experience it weathers off and starts to fail in about six months. Your best bet is to get some Owatrol EB (Emulsabond) and mix it 3 parts paint 1 part EB in your first coat of Sandtex. Emulsabond will stick to pretty much anything, even glass, I've known it, when mixed with masonry paint, to stick to Fletton bricks which are a nightmare to get masonry paint to stay on.

 

[misterhelpful]

That could be a good shout, ic1927.

Owatrol make a lot of good products but because they are not all readily available off the shelf I, and probably many others, tend to forget about them.

 

[Endofmytethers]

Hi,

Sorry for me delayed post, the situation was getting me upset and all Thompson ' s were saying (or rather their technical team) was not to paint it as the paint would just flake off.

Thank you so much for the replies. The weather shield has been on for about a month now. As I have got the scaffold up (which needs to be dismantled soon) I have to do something quick. Are you quite confident about the EB stuff? Where is the best place to buy it from online? (I'm assuming online is best?)

Thanks so much again!

 

[foxhole]

If you have water thru brickwork the you must have a leak. Brickwork does not need sealing.

 

[Endofmytethers]

Iv had several people look at it, it's an end terraced house, getting wet patches on the inside of the gable end wall, it's just been repointed, and wet patches get worse after it rains, roof is new. It's between the chimney breast and the side wall of bedroom, going across the top next to the ceiling.

 

[misterhelpful]

If it's getting worse after it rains then, as foxhole says, there must be a leak. You say the roof is new but how new do you mean? Is there a chimney at the top of the gable wall where lead flashing may be damaged or missing, as this is generally the cause of something like you are describing? If not, then there must be another source for water to penetrate.

As for the Owatrol EB, I personally can't tell you for certain if it would work in your situation but, like ic1927 has mentioned, it does help paint stick to many surfaces.

 

[Endofmytethers]

Thanks for the response mrhelpful, roof is about 5 years old but looks solid, many have said so, flashing looks fine too, which is why I'm confused as to where the water is coming from. Will post some pics up soon, which may help.

 

[Endofmytethers]

All - I have posted some pics up in my album - would be grateful to get your thoughts on the quality of the lead flashing etc. I will try going up to check the flaunching tomorrow.

 

[misterhelpful]

Although the finishing of the pointing leaves a lot to be desired, it looks as though there are no major defects to allow water through but, as you suggest, a few minor cracks here and there could be the source.
The flashing looks good but it has lifted a little 2-3 courses down which could allow driving rain to penetrate. Would that be in the area where the staining in the loft and damp in the wall is?
We don't know the condition of the flaunching, and we certainly don't expect you to risk getting up there just to take a picture, but it could be something that needs attention.

These are not really my areas of expertise so I could well be missing something. (Sneaks in a disclaimer! )

It might be worth using a pliolite masonry paint, like Johnstones Stormshield, which I have found highly resistant to rain but it's a bit harder to use than their water based paint. However, if there is a different source for the damp, or an adhesion problem, it will make little difference which type of paint you use.