Seal flaunching after bargeboard replacement?

[Mike Halmarack]

I'm replacing the barge boards of a concrete tiled roof. The flaunching is rock solid and would be difficult to remove from the tiles so I'm intending to put a bead of mastic between the flaunching and the new barge boards to seal the joint. The problem is that there are some hairline cracks in the flaunching at right angles to the barge board edge.

the cracks occur at the narrowest points where the tiles step. I don't know if I can rely on finding some kind of paint-on sealing solution to fill these cracks, as it waterproofs the rest of the mortar, or whether to carefully enlarge and dovetail the cracks so that I can fill them with mastic more effectively. Any advice on this?

[Kipper at sea]

The hairline cracks are due to the suction in the tile batten end drying out faster than the cement bed between the tiles

[Kipper at sea]

Best way is to rub a little smear of clear silicon into the airline crack

[Kipper at sea]

Best way is to rub a little smear of clear silicon into the airline crack

[The Natural Philosopher]

I think its high time you stopped flaunching those poor seals.

[Mike Halmarack]

That seems to make sense. Thanks. So, for future reference, sealant on the batten ends before flaunching would help prevent the effect.

[Mike Halmarack]

With a hairline crack, it's not going to penetrate very far. I did find this stuff yesterday:

may be more suitable, especially if I can find it available locally.

[Kipper at sea]

If the tile battan isn't cut back far enough from the edge of the gable or verge, the result is a hairline crack. After about 10 years the end of the tile battan slowy rots

[Mike Halmarack]

Thanks, that's very useful info for future reference. Meanwhile this roof is 25 years old, but the state of the battens is only going to be guessed at, with any luck.