its certainly easier getting the experts in but also very expensive.
no need to prime the exterior pebble dash, just paint over it with a good quality exterior masonry paint from one of the big manufacturers, dulux, crown, sandtex etc, the walls are already textured so make sure you buy a normal untextured coating. firstly though, make sure the pebbledash is in good order and not flaking off, otherwise it may need completely stripping and re-coated.
the difficulty in coating pebbledash is that it is hard to get the paint into the gaps between the aggregate. a roller will probably not work. a brush would be good if you use a dabbing motion but this will take a long time. the pros would probably spray it on, this is the quickest method and would give a very good finish if your competent with a spray-gun. you can hire sprayguns and compressors at most good tool hire shops. get the shop to show you how to set the gun up and use it and then have a little practice on some scrap wood.
you may have to apply 2 coats though to get a good even finish, depends on how good the paint is.
and a word of warning from someone who works for a paint manufacturer. dont bother with the door to door companies who claim they can coat your house in a wonder coating that lasts 20 years. its just normal exterior masonry paint, they just charge the earth for it and to apply it.
