bad paint job any answers?

margi_g

I had the outside of my bungalow painted in August of last year and in April the paint started peeling off. This was paint I bought myself and the painter is coming back to rectify it this week . The question I havent been able to get answered by him is why it happened in the first place? This building has already been painted 10 years ago and was no problem ( it was painted by someone else then). The pain has fallen off the wall and showing the original render. Since it has been fine until this man painted it what happened that it is falling off now? Any ideas? I t want to know the reasons this has happened before he comes here and repaints it and finds it does the same thing a few months down the line

Aylesbury_Duck

It will either be poor surface preparation or poor choice of paint (wrong type or poor quality), or a combination of all of them. To help get to the source of the problem and the possible remedies, here are some questions.

How much research did you do before choosing the paint?
What paint did you buy and how much did you pay for it?
What did you ask the painter to do? Just put on the paint you bought or did you ask him to do more than that, i.e. surface preparation, any primer, etc, etc.
Do you live in an area with unusual environmental conditions and temperatures, e.g. on the coast?
What preparation work was done by the painter before he applied the paint?

margi_g

The paint was Sandtex Masonary paint,used it before without any problems. The painter put PVA on it before he painted it .Could that be the problem

Doozergirl

I don't have any experience with render, but I guess it's the same as plaster.

If you paint fresh plaster without a mist coat, the plaster sucks up the water in the paint too quickly and you don't get a good bond between paint and plaster. It's usually fine until you redecorate, when the original paint gets wet again and starts to peel from the wall as the bond is poor.

There's also the point that there is no reason to use PVA with paint. I've heard of people putting on fresh plaster, which can be a problem itself, I have never heard of people putting it in between paint coats.

I'm not a chemist so I don't know why you don't do it, but if paint needs a certain chemical in it to help it bond, there's no reason why they wouldn't put it in!

Tom99

[FONT=Verdana, sans-serif]I agree, since you say the original render is exposed it sounds like its a problem with the previous paint's adhesion to the wall.[/FONT]
[FONT=Verdana, sans-serif]With any luck what's going to fall off has fallen off and can now be painted over.[/FONT]

Aylesbury_Duck

You didn't answer the other questions. Did he just put PVA straight onto the old paint and then paint it? I agree that it seems as if the original paint job wasn't done properly and that the PVA and repaint has reacted with the old coat and caused it to come away.

margi_g

this bungalow isnt in an area that gets too much bad weather . I dont undertsnad why the old paint didnt react the same way.the old paoint job showed no sign of this happening

Aylesbury_Duck

margi_g wrote: »

this bungalow isnt in an area that gets too much bad weather . I dont undertsnad why the old paint didnt react the same way.the old paoint job showed no sign of this happening

Because they're not equivalent. The old paint was bonded to the render somehow. Perhaps not perfectly but it clearly never came under enough force to come away.

The new paint, or the PVA, or both, have reacted with the old paint in such a way as to weaken its bond to the render.

I don't think you'll be able to pin down exactly who or what caused the problem. It could be that the original paint job wasn't done properly all those years ago, it could be that the PVA has somehow reacted with the old paint and caused it to come away from the render, or the new paint could have done the same thing. As for a resolution, it would seem to me that the whole lot needs scrubbing thoroughly first. That will expose any other weak points where the paint is coming away. Then the surface needs preparing properly and finally re-painting with suitable paint. In the majority of cases of paint failing, it is the preparation that is at fault.

Furts

margi_g wrote: »

The paint was Sandtex Masonary paint,used it before without any problems. The painter put PVA on it before he painted it .Could that be the problem

Why? Ordinary pva is not water proof and you do not use it outdoors. Water resistant is available, but far less easy to buy, and far more expensive. I suspect this is your problem.

armchaireconomist

I'd be annoyed if the painter hadn't PVAd the surface prior to repainting. Doesn't need to be waterproof either, as Sandtex paint applied becomes the 'barrier'.


It's either poor prep by the painter (presume he cleaned it all down beforehand?), or the original paint has had a poor bond to the masonry. Just re-paint that section and get on with it.

Furts

armchaireconomist wrote: »

I'd be annoyed if the painter hadn't PVAd the surface prior to repainting. Doesn't need to be waterproof either, as Sandtex paint applied becomes the 'barrier'.


It's either poor prep by the painter (presume he cleaned it all down beforehand?), or the original paint has had a poor bond to the masonry. Just re-paint that section and get on with it.

There is a flaw with the logic here. If the Sandtex is not perfectly applied, or goes thin in places, or cracks or has rain before dry then wet will get behind and at the pva. But there is also another issue. Say the original coating was breathable, micro porous or whatever. The pva has formed a seal over this stopping the original paint from working. A build up of moisture trying to breath out could blow the coating off the wall.

I am still not convinced any pva should have been coated onto the wall. But if this is the issue it will be a real pain trying to sort matters.