Mend my roof leak!
 

Mend my roof leak!

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So, recently, the bay window at the back of our house has started leaking. Trying to find a local roofer, but people aren't answering queries or showing up ... So, thought I'd attempt a repair myself. I mean, how hard can it be?

It's a double height (2-storey) rectangular bay window, with a flat, looks like glass fibre roof. There's no leak into the bedroom on the first floor. But, it is leaking through the top corner of the bay into the dining room below, on the ground floor. The side return of the bay is also part of the side window of the adjoining conservatory, and there is a bunch of flashing where the conservatory roof joins the bay window at about the height where the leak seems to be coming from. Suspect that is where the water is getting in.

So, without sketches, photos (it's dark right now) or floor plans, who here can diagnose the problem?

And, if I got a roll of self adhesive 'flashband' tape from Screwfix, I'd have a decent chance of an emergency repair, right?


 
Posted : 27/01/2026 8:14 pm
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That's all about as clear as mud but when you identify whare the leak is I suggest a tube of red or grey roofers' special mastic in a mastic gun will be more succesful than your tape, especially if you dry it off with a hair dryer/heat gun and give it a wipe with universal solent before applying the mastic.


 
Posted : 27/01/2026 8:45 pm
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Posted : 27/01/2026 8:52 pm
nicko74 reacted
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There are sealants and tapes that you can apply to wet surfaces, but obviously better if you can clean and dry the area for better adhesion/sealing.


 
Posted : 27/01/2026 9:47 pm
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I've had good results with flashband.   I does need to be warm to stick well iirc.  its only a temporary repair tho


 
Posted : 27/01/2026 10:44 pm
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Posted by: Edukator

and give it a wipe with universal solent before applying the mastic.

He may well be in the North. It'd take him ages to drive down to the South coast just to collect a bottle of that. 

 


 
Posted : 27/01/2026 11:17 pm
nicko74 and hardtailonly reacted
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Gorilla patch and seal works (*very,very unforgiving, wear gloves and old clothes and get it in the right place first time) 

see also evercryl.   (See comment above) 

try to lift stuff up and follow the damp stain to source before applying hideously sticky stuff at random

For longer term See also easy lead flashing , that looks a bit more substantial but I’ve not used it yet


 
Posted : 27/01/2026 11:18 pm
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As above, it's clear as mud, but anywhere that one surface joins/ is adjacent to another is absolutely a hotspot for water ingress and the first place I'd look. Even flashing done well is fine with regular rain and water, but when you get the volume of rain we've had recently, the drainage may not take the water away fast enough, and it can back up, causing the level to rise above flashing edges etc


 
Posted : 28/01/2026 10:16 am
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and give it a wipe with universal solent before applying the mastic.

 

 

He may well be in the North. It'd take him ages to drive down to the South coast just to collect a bottle of that. 

Obs a typo. He meant Soylent

 

image.png


 
Posted : 29/01/2026 3:48 pm
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Posted by: kayak23

It'd take him ages to drive down to the South coast just to collect a bottle of that.

Underrated comment 👏


 
Posted : 29/01/2026 5:20 pm