Our 1960's house has a spar dash exterior (small sharp stones, pebbledash
style).When we had our extension built a couple of years ago the builder
tried hard to match the new and old exteriors, but it doesn't look very
attractive. Despite the well documented reservations (once you do it has to
be repeated on a regular basis, etc) we decided to go ahead and paint the
house white.

Having never attempted to do it before we have a few questions for the
panel:

1. The stones (spar) are generally well stuck to the wall, but the guy that
was painting the neighbours' house suggested that, considering the age of
the original render, a 1st layer of paint mixed with PVA would be advisable
to ensure everything remains intact . Does it make sense? If so, at what
ratio?
2. How many layers will be required? Note that the house has never been
painted before.
3. Do we need to prime the walls?
4. Does the 1st layer need to be thinned, and at what ratio?
5. Should we use oil or water based paint, and why?
6. Which paint should we use (we live in one of the wettest parts of the UK
if that makes a difference)?
7. How often should it have to be repainted to achieve an acceptable
appearance?
8. Roller or brush? The stones are very small and sharp. Any recommendation
of a make/type/etc? Time no issue (pretty much) - quality of finish is the
main concern. Don't want to use spray (long story...)
9. Should we just get the experts in? The gable ends (it is a detached) are
very high and difficult to reach, so we will have to get them to do those
anyway, but we were hoping to do the front and back ourselves (better
finish, and cheaper overall).
10. Any thoughts on window sills (they are concrete ones) - should we leave
them or paint as well?

Many thanks in advance for any useful information.

J.