can i use PVA on flaking outside walls ?

I have masonary paint on outside walls which are now old and patchy have scraped off loose paint ready to repaint but would like to know of anything recommended to help seal the walls?
philco, June 2013


done
Jeff Howell writes in his book - Looking After Your Property....(Amazon £15)

Resin-based stabilizing solutions are generally used on exterior work. For inside walls, water-based PVA should be sufficient.

Peccavi, June 2013