Repainting exterior: painter says don't prime?
Hi, I'm new the old house forum, hope this is the right place to post this! Our house is 45 years old, with painted wood board and batton siding. The old paint is in fair shape, with no peeling, only a little checking in a few spots, and a few areas where you can sort of see the wood through it. No idea when it was last painted, probably 15 or so years.
A highly recommended painter looked at it. He said he would not prime first, because paint sticks really well to paint. He would powerwash the surface to remove the oxidation on top, and put the new paint directly on, only priming those areas where you can see the wood showing through. For the areas with checking he would sand and prime.
I was surprised about the primer issue. I want this paint to last fifteen years. I had been under the impression it would be best to prime the whole thing first.
My questions are:
1) is it normal to not prime in these circumstances?
2) since the old paint held up so well and is probably 15 years old, does that mean it was oil based? If I'm putting latex on top, doesn't that mean I need to prime first?
Thanks so much for any advice you can give!