External paint job repair - advice please.

We had our house exterior painted last November. Mostly it's fine, but the paint on 8 windowsills of the new extension (despite being completed a good six months before being painted) is flaking off in a major way. I assume this was due to rain before it dried.

It's not a big job so I'll do it myself, but I'd appreciate some advice. Will it be sufficient to roughly sand down the sills to remove loose paint and apply a couple of coats of Weathershield? Or do I need to apply some kind of sealant to prevent more flaking?

Many thanks.

The 8 windowsills of the extension were prob new and were also prob powdery. These should have been treated with a stabilising solution. To fix, scrape away the large loose paint bits with a scraper, use a wire brush to remove the smaller ones, then sand with some sandpaper. After this dust off the sills. Apply the stabilising solution, [broken link removed] . Then apply 3 coats of paint over the solution.

Many thanks, philboy. You'd really think that a professional house painter should know that! The irony is that if we'd done the job ourselves we would have checked that kind of thing to be on the safe side. Grrrr. It's going to take me a weekend or two to correct it. But thanks again for the reply.

It Shouldnt take that long. Apply the stabilising solution and allow that 24 hours to dry. Then you can apply the paint. You can apply the coats one after another as soon as the previous coat is dry, you'll prob get the 3 coats on in the one day.
I dunno, maybe the guy you got came in on the cowboy express train ;-) Give me a shout if you need any more advice.