Leaking Flat Roof - Help Please

[rossyl]

Drilled a hole directly where the leak was.

I have drilled a hole where the leak was. Looked up, and I can see the inside of a chimney and the inside of a chimney pot.

The camera is facing directly upwards to where the leak is coming from. You can see the inside of a chimney and the chimney cap at the top. You can also see the wood holding up the chimney.

The chimney breast would have been in our room. That was removed, so the chimney sits above the plasterboard ceiling in our room.

EDIT: The water is dripping of the flashing you can see which seems to be towards the bottom of the chimney - which is why I always felt the dripping had some "force" behind it - as it was dropping from height.

Where the water is coming from that is dripping onto the flashing around the base of the chimney - that is a question mark.

The torch is somewhat in the way on the left

How do I make the chimney cap completely water tight?

 

[rossyl]

In green I've put an arrow to the base of the chimney pot.

Above that is some flashing. Which I have put some red lines on.

It is the edge of that flashing (near the red lines) where it is dripping from.

Given where it dripping from - I am guessing it is coming from:
- the top of the chimney stack around the edge of the chimney pot (though i have put a lot of Cromapol here)
- somewhere else on the top of the chimney
- or water is getting inside the cap and then running down the inside of the chimney? is that possible?

It doesn't need sideways rain to start dripping, a reasonable downpour will do it. Light rain will not cause it to drip.

Any ideas appreciated as to how I now stop this leak.

Thanks

 

[^woody^]

Nice bit of detective work!

You could just Croma all the flauncing around the pot, but then you'll need to Heath-Robinson some sort of lead cap for the pot.

Or, remove the pot, slate over the old flue and re-flaunch the chimney. Or replace the pot with a capped clay type.

Either way, the flaunching on the chimney is important, so if it is loose and flaky, the Croma wont last long. So if that flaunching needs doing, then get it done - and it needs to be done right with a strong sharp sand and grit mix (not building sand) and it rounded off and the surface trowelled smooth to throw water off it. If that's done, it wont need any additional croma on the top.

 

[HERTS P&D]

Well Done Rossyl, it makes a change when a poster does what we ask them to do. You have and found the problem straight away.

Andy

 

[HERTS P&D]

Leaks never appear where the rain comes in ( Building Fact !!!!)

This time it was.

Andy

 

[rossyl]

Thanks guys - I appreciate your support and help - it really gave me the confidence to go exploring.

Flaunching was not flaking. There were a few very superficial hairline cracks. So, prior to today, we had absolutely covered it in Cromapol about a week ago. That had obviously not stopped the leak.

Having found the issues today, and watched the drips (as they landed directly on my eyeball - gross), I think it might be running down the inside of the chimney pot.

Once I had a bit of understanding, a Google search led me to this: https://www.fixmyroof.co.uk/videos-and-guides/chimneys/chimney-capping

We have "Pepperpot" capping and, from reading that website, I think it might be causing water to run inside the chimney pot. As the distance from the top of the chimney pot to my bedroom ceiling is not far, the smallest amount of water is causing the "leak".

So...I'm going to remove the Pepperpot Cap and replace it with a C-Cap - fingers crossed.

Thank you Andy and Woody I would not have done all of this without your help and support, thoroughly appreciate it. I had so much 'doom and gloom' advice prior to today that it had really got me down. I feel much more positive about it all now. Thanks very much.

Will update once I've done the capping, but probably won't go up on the roof till it has stopped raining (I don't like heights!)

 

[datarebal]

common mistake is not to seal the cowl to the pot. currently tracking the contour of the cowl into the pot/stack