How to find a roof leak that has gone away?

[ProDave]

Almost 3 years ago, I fitted the wood burning stove and it's flue, detailed here

All was fine until last winter, when every time it rained, there was a drip drip drip of rainwater coming off the sloping section of flue above the mezanine floor in this picture

 

 

The water appears to be running down the outside surface of the flue pipe and dripping off the top or bottom of the sloping section in that picture.

 

I have put off investigating as my own roof ladder is shorter than the roof so to use that means putting up a scaffold tower to reach up the roof from the platform.

 

Today I borrowed a longer roof ladder so it can go up without scaffold, then spent some time on the roof, first with a watering can, then later with a hose, wetting the flue pipe, all the joints, the flashing where it goes through the roof, wetting the tiles above and to the sides of the opening.

 

The hose has been running over an hour (and is still running now on the base of the flashing) and not a drop has been seen inside.

 

What next?  give the borrowed roof ladder back and wait for the next real rain?  If it were my own long roof ladder it would be staying in place for some time.

 

Just how do you find and fix a leak that has gone away?

[Onoff]

Mad idea but it's not condensation is it? Was the stove on at the time you were hosing it down? Thinking cold rain on a hot flue.

[ProDave]

No difference between hot or cold weather or stove lit or not.  When it rained, the drip started pretty quick, so I am surprised sitting for a long time on the roof with the hose did not find it.

 

I want a proper downpour of rain right now to see if it will leak again.

[TonyT]

Wind is blowing rain up through a flashing?

[Mr Punter]

4 hours ago, TonyT said:

Wind is blowing rain up through a flashing?

 

Is that a blues song?