Painting a 20-yr old rendered wall. Preparation?

I plan to paint the rendered gable end of my house for the first time. It was rendered 20 years ago. Is there any preparation I need to do, to maximise the durability of the planned paintwork?

TIA

Al

Reply to
AL_n
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Check the rendering's still attached. Then, if it is, thoroughly clean it.

I had what looked like perfect rendering on my flat three years ago, which had been applied a couple of decades earlier, which turned out to be sort of attached in places, but was mostly staying up due to not having the energy to fall down. 90% of the tap tests had that horrible hollow sound.....

Reply to
John Williamson

That is exactly the description of what I found on one of the gables here last summer. With the exception that a few square yards had found the energy to fall off in the previous winter.

Got proper scaffolding put up and put a chisel behind it, it would come away in great chunks. I never really worked out why it had been rendered in the first place, the pointing was 99% good and the stones in good condition. I suspect it failed as who ever put in on didn't remove the paint that was there first so when the paint's bond to stones or render failed...

I pressure washed the entire wall with an ordinary domestic pressure washer and "dirt blaster" jet. That removed most of the old paint, algae and anything else loose. Found a few weakness's in the pointing. Patched that up and painted with Dulux Trade Smooth Masonary Paint, it's surived one winter and looks pretty good.

Reply to
Dave Liquorice

Id pressure wash it to get lichen off, and then put onb a 50-50 thinned coat of whatever it is you are using.

Think mines done in Dulux exterior. That worked well and is holding up

10 years later.
Reply to
The Natural Philosopher

Yep.

The test for "powdery" is doe you end up with the old paint on your fngers if you rub it gently. Even then I'm not convinced that a stabilising solution is any better than a slightly diluted first coat. IIRC the first coat I used last year (and this when I've finished the patching) was about 10:1 paint:water.

Brush is damn hard work if there is any texture to the surface and tedious in the extreme. Rollers work but you need a decent one. Dulux Trade Heavy Duty Woven Sleeve(*) worked and lasted well, two and a half two storey gables with two full coats on smoothish pebble dash and stone. The dilute first coat was brushed. I don't think that roller was quite dead but was starting to moult a bit quicker than at the start. Give a new roller, no matter the make, a good washing and scrubing before use to get rid of any loose pile.

(*) Be aware that roller is a 1 3/4" core the sheds sell frames for rollers with smaller cores...

Reply to
Dave Liquorice

I found if painting textured render (i.e. like stipple finish or roughcast), those small 4" wide rollers can be good. Often you can't get enough force onto a full width one to work the paint into the texture, and the small roller works faster than a brush.

Reply to
John Rumm

John Rumm wrote in news: snipped-for-privacy@brightview.co.uk:

Thanks to all for the tips. I followed the advice about pressure cleaning and then using a diluted coat. It all seems to make good sense.

They say that a lick of paint hides a multitude of sins. Well this paint job actually seems to have shown up a load of sins - like what a amateurish rendering job it was. I think I may have to apply a coat of really thick textured emulsion to try and disguise the patchiness of the cement rendering.

Al

Reply to
AL_n

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