We had the exterior plywood soffits and fascias painted a couple of years back.
There's a section where it's all peeled of, in giant flakes, right back to the plywood, which is in fair condition. It's like the paint just didn't 'stick' to the wood.
I'm going to take this back to bare wood and re-paint myself.
What should I do do ensure better adhesion? Presumably I need to use the correct undercoat or somesuch. Why did the previous paint job fail?
It could have been any number of things - a chemical treatment on the wood, the plywood was damp prior to painting etc.
Give it a sanding down and make sure it's dry before painting, then just use normal undercoat and gloss, 2 coats of each for a long lasting finish
Don't forget the primer - most important when starting from a bare surface.
My method would be:
Prepare the whole job by scraping and rubbing down to remove all loose material and too feather-edge around missing paint, wash with white spirits (removes grease etc) and allow to dry thoroughly.
Give all bare and problematical areas a coat of *aluminium* wood primer (see link
Rub down primed areas and then give the whole job either:
A couple of coats of undercoat and one coat of gloss. OR one coat of undercoat and two gloss coats. OR even two coats of each - obviously rubbing down between coats.
On external works, I look for at least five years between painting jobs (particularly along roof and hard to reach areas) and I tend to use two coats each of undercoat and gloss to build up the paint thickness to give me the 'life' that I want - along with ensuring proper preparation (and it's the preparation that takes the time *AND* makes the finish along with good quality materials [which are not necessarily the dearest or most well known).
Hope this helps
Cash
Was it originally bare wood, or wood coated with a melamine finish? I had the latter on my garage and had the same issue, paint just wouldn't adhere to it.
I covered it up with uPVC fascia boards instead though I now find, looking at google, that special melamine primer is available.
Actually I have seen this with new wood surfaces painted after treatment with spirit based Dulux wood preservative after about 2-3 years. And it doesn't seem to matter what primer, undercoat and topcoat system goes on top of it.
I have a feeling that they had something in the mix that acts like a mould release for the main paint film and it is related to the move towards low solvent paint formulations. The behaviour is different to trapped moisture under the paint which is also present but nothing like as bad as these big flakes literally jumping off the woodwork.
It is mostly parts that face south and get the weather that flake off so I guess it is some variant of thermal stress and flexure.
Crap paint probably. Acrylics are ok for an undercoat but hopeless as a topcoat
What did the instructions for the preservative say about overpainting, I wonder? Some preservatives are in quite oily carriers and take a long time to dry out, so don't help with paint adhesion. FWIW Dulux do a combined preservative-primer as part of their Weathershield system, and it seems to be Good Stuff (IME):
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