? re external painting and wood rot

[ss]

History: Bought house 5 years ago external paintwork in poor condition, flaking etc. Checked for any rot and only one small area. This was at a mitre joint the piece of wood that sits on the concrete window sill That the window frame then sits on. It was about one inch each side on the mitre, scraped out used wet rot hardener and then 2 part epoxy filler, been sound for last 5 years. However the opposite end of that window frame the same has ocurred wet rot about 1.5 inches either side of the mitre joint. This wood was sound

5 years ago and was sanded undercoated and 2 coats of external paint so surprised it has got rot. I will scrape out use wet rot hardener and 2 part epoxy to repair it but my question is have I done something wrong? Or should there be anything else I can do when repainting to ensure I dont get a repeat of this especially where the joints are concerned. I normally sand undercoat and 2 coats of external paint (oil based) and all looks smooth and good when done.

[David Lang]

Rip it out & stick a uPVC in there.

[Brian Gaff]

Capillary action between window frame if plastic or metal where it joins wood. I've had this and another thing while I'm in this mood, people who put on wallcoat tend to spray up under window sills making a wonderful water trap of the wood and of cours it rots the sill in a couple of years. Brian

[ss]

Its all wood no plastic or metal but I guess it has got in somewhere. I will repaint the complete frame this summer. It is actually a porch the previous owners built in the 80s so wood has been good til recently.