Mystery roof leak - updated - found the cause!

dharm999

As title says, we have a roof leak that I can’t get sorted.  The sloping roof is slate tiles, around 100 years old.  Have had 3 different roofers around to look at the leak.  The leak comes in to a bathroom in two different places, one about 4 feet in from the wall, and the other from the top of the wooden window.  It’s a sash window, and from the outside looks in decent condition.  It’s not a huge leak, a drip every few seconds when it’s raining

The first two roofers patched the area above where the leak is by putting bits of felt under various tiles, and the third one I asked to strip the tiles off above the affected room and replace the felt rather than small patches.  I also cleared the gutter outside the window, as it had a lot of leaves in it but wasn’t blocked.

But still no improvement.  The leak only happens intermittently, not every time it rains.  It rarely leaks in the summer, when it rains, and is worse in the autumn and winter.  I thought it might be the felt perishing, and getting wetter in the autumn and winter and water soaking through, but it isn’t that.  The third roofer said that the nails in the slate tiles they looked at had rusted and it could be a small leak somewhere not above the affected area.  They also said the roof will need fully stripping back and the slate re-fixed with new nails, but there aren’t any other leaks, so I will put that off for now.  

Do I have any options now, other than getting a large area of the roof stripped of the slate tiles, to see if the source of the leak can be found.  The roof is around 90 square metres, so it won’t be cheap, but I can’t see I have any choice now.  Anyone any ideas as to what else I can try?

Thanks

stuart45

Try and get some photos, and from inside the roof space of possible.

dharm999

Can’t get in to the roof space unfortunately as there is no access to the roof.  The house has a flat roof with sloped slate tiles on the sides, and the leak is on one of these sides.  I’ll post some photos in the morning when the light is better

twopenny

Is it possible it's pooling on a part of the flat roof and dripping behind the tiles on heavier rain.
In summer it could evaporate.


Do you know anyone with a drone? Not as weird as it sounds, lots do.
Ask them to fly it over the rooof after raiin and photogaph for a smalll cash gift.

dharm999

I’ve attached some photos that have internal and external shots.  The last one, you can just see the dried water marks from where it was dripping from the top of the window frame.

dharm999

twopenny said:

Is it possible it's pooling on a part of the flat roof and dripping behind the tiles on heavier rain.
In summer it could evaporate.


Do you know anyone with a drone? Not as weird as it sounds, lots do.
Ask them to fly it over the rooof after raiin and photogaph for a smalll cash gift.

Don’t think it’s that.  I’ve been up on the flat roof, and it has leaked in the past, and where water has pooled it has left a mark, but no mark on the flat roof in the vicinity of the leak in the sloping tiled roof

FreeBear

Have you got hidden box guttering up there ?

There appears to be a suspicious crack on the centre line above the window - It might just be a join in the fascia...

dharm999

FreeBear said:

Have you got hidden box guttering up there ?

There appears to be a suspicious crack on the centre line above the window - It might just be a join in the fascia...

Yes, that's the guttering, the 'crack' is the join where two gutter pieces meet.  When it rains it doesn't leak from there

dharm999

Here’s a picture of the end profile

dharm999

A couple more pictures of the roof area either side of the area of the leak

dharm999

Anyone have any ideas about this?