Help needed to improve a stupid roof design

[Evigilo]

Hi all,

 

Please humour me as I try to explain what the issue is. I'll include some photographs which will hopefully help it to make sense. When I purchased my house, it had a conservatory built into a corner of the rear of the house so two sides are the brick walls of the house. In order to add the conservatory, the former owners had part of a single story roof removed and built up the wall so that the tiles stop short and there's just a lot of flashing on top of the felt and rainwater flowing down has to puddle and sit at the base against the built up wall. The polycarbonate roof of the conservatory is basically triangle shaped sheets that converge in the corner. On the troublesome side, the roofing bar sits on top of the sloped built up wall. At some point in the past, holes have appeared in the flashing against the built up wall and water has been seeping into the wall, part of which is a modern cavity wall and part is the original solid wall which has soaked the leak up like a sponge until it became saturated and we saw paint bubbling and could smell damp. When I pulled out kitchen base units, there was mould on the wall behind them. I imagine the soaked cavity insulation was the reason that was so bad, and of course it was out of sight until the smell got so bad I had to investigate. It's such a ridiculous design.

 

I've temporarily flashed over the leaks (please ignore how bad it looks!) and pulled off the plaster on both sides of the wall to help the wall dry out over the summer. The cheap roofing sheets they used need replacing but I don't want to spend money on this only to have it happen again. I did consider having the flashing replaced with lead flashing and popping new polycarb sheets in but I doubt I'd trust it. Therefore, I've been considering other designs for the roof, ideally involving taking down the raised wall to it's previous height (the conservatory was added years after the extension) so that it can be tiled and have water running off into guttering - and the rainwater from the main roof could also be directed into this instead of the current arrangement of a downpipe suspended over the roof. However, that would mean either flat roofing the conservatory as there'd only be a few inches between the top of the frame and the bottom of the new guttering and the room behind the conservatory is already dark so I don't want to take away all the light. Roof windows and the like are beyond my skill and budget probably.

 

I've considered taking the wall down to the proper height so that the tiles can be replaced and guttering installed and swapping the conservatory roof design to a centre pitch of some kind but that would involve water flowing towards the wall below the guttering.

 

I'm hoping there are other possible solutions that are better than mine! I'm also hoping the photographs illustrate my dire explanation. If not, I'll seek to explain anything that's unclear or missing. Thanks in advance for your thoughts 

Edited October 2 by Evigilo

[Evigilo]

A couple more photos showing current roof design...

[markc]

Interesting bit of design. To rescue this I reckon you need a good GRP roofer who would strip back and effectively form a waterproof and tough trough to prevent any more water getting under the tiles or flashings and funnel it to the gutter / down pipe

[marmic]

the problem could also be beyond the surface in cavities?  I havent studied too closely but not immediately obvious looking bricks where you have them.  If where you have roof abutment and stepped flashings there are cavities and there are trays in place they could be invisibly directing the water internally into that corner.  Or spread more evenly if there aren't any............

 

[gaz_moose]

the rest of the conservatory looks pretty old. i think I would knock it all down and start again. 

My conservatory was wooden built with twin wall roofing and i gave up bodging it with flashing tape. now it has a OSB3 and EPDM roof and is fantastic.