In article .com,
"dg" writes:
These were typical on many system built properties from the 60's, and
the problems that we have to deal with today are water penetration due
to rotten/punctured/defective sarking felt at the eaves, and also
problems with gutter leaks or overflowing.

This causes water to soak backwards into the wall, where otherwise it
would drip from a soffit.

Use a felt support tray.

I replaced the facias on the back of my house this summer (next
summer, the front gets done). Additionally, I stripped parts of
the roof and replaced the felt, and fitted a felt support tray
all the way along. (Note you don't need to strip off any of the
roof just to fit a felt support tray, although it will be easier
if you lift off or push up the lowest row of tiles, which you'll
need to do to replace the facia anyway.)

--
Andrew Gabriel