paint on exterior brickwork is cracked and split?

Do not paint brick/stone at this time of the year it's to damp, best to wait for early spring.
Scape off all the flaking and peeling paint carefully so as not to damage the brick/stone. Depening on how thick the paint film is you will have to feather off all the hard edges otherwise when you repaint you will see the edges of the old paint show thro'. Use good quality external emulsion such as Dulux Weathershield. Paint a first coat of stabilising fluid to all the bare brick/stone followed by two or three coats of Weathershield. If done well it will not need doing for at least 6 years or more.

BarryF
December 2009