if it's a flat roof then the seal between the wall and roof has most likely opened in places and needs re-sealing with flash band flashing roll obtainable from most DIY stores or buidlers merchants.
If a straight [Pent] and not peeked tiled roof with cement fillet against the wall and overlapping on tiles it may have pulled away from the wall in a couple of places. Could be tiles at top slipped, If lead flashing could be rain blowing under lead into gap especially if gap between top row and wall is larger than max of 25mm [allows for expansion in hot weather] This can be over come with bituman mastic silver coloured to match the lead. Gently ease the led up and clean out loose matter with brush then squeeze mastic under lead on to the tiles about 25mm up so you don't see the mastic when the lead is dressed down back on to the tiles, the mastic bead will stop rain being forced up in to the gaps. Don't matter if you can see the bead of mastic it just looks tidier if you can't.
If you can take a digital picture of it email to robertwhiting76@hotmail.com I'll try to help refering to photo's. Be quick I'm away to Devon on Thursday but can pick up emails at my daughters place. Who's going to do the repair?. No email after Friday I will assume you've had it fixed.
Bob
September 2008
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