Most likely it was a poor paint job, the S side may have been hot from
the sun, or was stained when to damp and cold. Stains are not suposed to
peel, and dont if aplied right. Scrape everything loose off and stay
with stain not paint. Is it possible paint was used last time. Was
everything clean. Cabots has good oil stain, but acrylic will hold
colors better. Read a Consumer Reports ongoing tests of paint and
stains, it will help you alot.