Bay window leak problem - reposted as I can't see the one from 14/09/2004 ?

[Pete Cross]

We have a 30's red brick semi with double bays on front covered by flat lead lined roof ( the bay that is )and pebbledashed walls. In the recent heavy downpours rain has filled the lead tray faster than it could drain and then cascaded over the front. After about 2mins of this the water starts coming into the house from the joint between the top of the downstairs bay and the ceiling. I can only think it's either coming down behind the pebbledash then in at the top of the frame, or coming under the front and back up by cappiliary action to the same place. If I pulled the ceiling down inside within the bay should I see enough of the frame top/wall junction to be able to seal it ? or can you think how else it can be sealed without removing the pebble dash ? the bay ceiling looks to be plasterbaord with light skim of plaster and is about a foot below the room ceiling.

[stuart noble]

If it leaks after 2 mins it should a visible crack/gap. I'd start by gunning mastic into every crevice you can find. Don't know how accessible it is but there's not a lot you can do from the inside.

[Dave Plowman (News)]

IMHO, you're going about this the wrong way. Increasing the drainage would be the best answer. If the water level is getting past the top of the lead, something isn't right.