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Help! We are renovating a 300 year old norfolk flint cottage. We are
having problems with severe rain driving in above our new bathroom
windows (downstairs). It was damp before, but we thought it was to do
with the old windows and thick artex from the 70's. It seems to be the
whole side of the house. I have tried Thompsons sealer, but it has not
worked. The pointing looks in good repair, so I thought it must be
porous. So what should we do? Don't want to have a re-point if not
necessary.

Well flint is not porous so if it isn't getting in through the pointing
it must be getting in somewhere else. The obvious place is via a leak in
the roof. Once in the wall water can take a circuitous route downwards
looking for a way out.

I have an old Yorkshire hovel with 2 foot thick rubble filled stone
walls. Twice in the last 30 years I have found a continuous thin stream
of water running out of the wall from above a window during heavy rain
but in neither case has there been a recurrence and I have yet to trace
the source of either leak. If it happened every time it rained I might
have a better chance of tracking the leaks down and more incentive as
well.

I believe flint walls generally have a mortared core rather than loose
rubble but such cores are likely to contain sufficient voids to provide
a pathway for water, particularly after 300 years, and could make the
actual leak even more remote from the resurgence than would otherwise be
the case.

--
Roger Chapman