flat roof leak views appreciated

[dandare50]

We had roof works done in 2014, completed around september.
These were to the pitched front roof (new valley liner and complete strip off and put back
on all ridges and cement up valley and new flashing.
At this time we had no issue with flat roof and had not had since 2011 when we moved in.
May this year and flat roof over bathroom starts to leak.
The flat roof connects straight under the bottom of eaves of pitch roof.
(no gutter)

When they did the work mentioned above they used a few of the tiles from the back for the front job as must have broken a few and replaced with the reds shown in pic.
They are the same tiles, Redland 49, but are not identical.
Main difference being the interlocking grooves; old ones have a double groove and reds have just one groove.

Do you think the reds could be cause of new leak. They happen to be directly in line with where the leak is coming through in bathroom which is raising suspicion. Also this has happened quite soon after the other work completed. Flat roof covering is old but seems fine and they said at the time it doesn't need any attention.

We spent a considerable amount of money on the other work so are hoping this is something straightforward!

Thanks for your time.

Dan

 

[Crystalclear]

The first lip of roofing felt, that sits just after it comes out from under the red tiles? have you checked using a flat screwdriver, if it lifts up?

The felt that sits under the tiles? how far up behind do they go? If it's not far enough, heavy rain and wind could be pushing the water under and down to your bathroom ceiling?

 

[^woody^]

There should be a layer of felt under the tiles and this is the waterproof layer, not the tiles themselves.

That felt should be overlapping the flat roof felt, with some other detailing to stop driven rain up and under the first row of tiles

Essentially, no, those different tiles will not be the cause of any leak, but whether they did something to the felt when changing them is something to look at.

 

[ree]

The roof troubles started, but apparently sat in waiting, when that flat roof was installed. There are better ways of detailing the flat roof and the junction.

Why not remove (providing that they are not nailed) the bottom course of tiles and post pics of whats exposed? Look for moisture below the tiles and on the underfelt.

You might also water test (just pour or spray water) and observe where the bottom tile drops to met the gutter in the very tight corner close by the soil stack. Does all the water go into the gutter, no drips? This inside corner area is very badly detailed.

Have you been in the loft and examined the suspect area and above it up to the ridge?

 

[dandare50]

Thanks both. To answer the 1st Q. The 'lip of felt' as you say I think does lift up which I didn't consider much as there
are a couple of layers underneath I think. The tiles have dug quite hard into the 'lip felt' itself and I have lifted them enough to scrape out any debris (which there was a fair bit). I can cover that 'lip' with some flashing tape and see it it helps.

As woody says when the tiles were swapped out damage may have occurred so I'll have to pull those tiles out completely and inpect.
But again the underlayer should cover that.

 

[dandare50]

I will take off the 1st line of tiles as I discovered today that they are not fixed just resting under 2nd line of tiles
which are hooked to the batton. I'll post some pics of that.
I have looked in the loft and I can see the construction of the flat roof itself main joists and thick ply over the top.
Then 1st layer (probably vapour control) followed by next layer of under felt and then cap sheet felt. I could also see a little
bit of water on the underside of the ceiling which would be about where the red tiles are but could not see where it was it coming in.
The leak also occurs in very light rain but takes time to build up.

 

[dandare50]

The ridge tiles were all re set when main roof was done 2014 so seems unlikely from there.

 

[ree]

How do you know?

I'm not suggesting its coming from anywhere - i'm saying to look in these places because its possible that moisture is entering in one place and presenting in another.

What do you mean by the "underside of the ceiling"? The loft side or the bathroom side?

Can you take a pic from the flat roof looking up the main roof?

 

[catlad]

You keep talking about new roof work all I see is an old roof with a new lead valley, I would looking at water getting in further up the roof and not being able to get out were the pitch roof meets the flat roof.

 

[Richard Morris]

My first thought would be to swap out those new tiles as if they are not sitting right it will allow water ingress.

The flat roof joint near tiles also looks like it isn't sealed properly.

These are both easy things to rectify and may solve the problem.

Regards Richard
aspectroofingservices.co.uk

 

[dandare50]

Some new pics as asked for - looking back up the pitch roof, around the soil stack corner (which I'm now very suspicious about) inside the loft looking at that area next to soil stack/gutter. Notice piece of lead resting on top of wall I think water may have dripped back in here and as lead is not fixed and given the water the space to get in. (This was where I noticed the water to the topside of bathroom ceiling apologies for incorrect info before Mr Ree).
I think the lead protruding from felt in close up may be the same piece visible from inside loft pic.

I've sealed over the 'lip of felt trim' with flashing tape where it was loose to gone under tiles with it as recommended.
What I haven't done yet is look closely at the corner in 'close up' pic of guttering/lead sticking out.
I need to get this all sealed in best I can.

What I have done so far seems to have disrupted the path of water as it's coming out of different hole in the ceiling (made by me to let the water drain in and not build up).

So I seem to be on the right track just don't know if this is the only point of entry yet.

Thanks all