Hi Wakebrownb,

Many years ago I rendered an old weatherboard house in East Brisbane. I had it done by a professional solid plasterer who warned me in advance that it would crack… and it did all over the place – mainly vertical cracks running the full height. Prior to rendering, I had bricked in under the house, so the foundations were very stable. The problem is that old timber homes have a lot of movement (eg in strong wind) which causes the render to crack. The plasterer later came back and filled the cracks with a flexible sealer which did help, but you could still see where they had been. Years later I sold the house to someone who ripped all of the render off then clad the walls with thick polystyrene sheets, then rendered over that. It came up good but I have not been back to look closely to see if it has cracked again.

In hindsight, one thing I would have done is made sure I had numerous vertical joins in the render running from floor to eves.

As stated by others, it is very important to make sure the job is done well –  I would be looking for guarantees it will not crack. Otherwise, painting seems a safer option and you don't run the risk of it loosing character in keeping with the area which could actually devalue the home.

Hope this helps a bit,

Cheers

Steve
Aussie Roof Insulation