Sorting out flashing on flat roof, advice appreciated.

[doogyscoot]

A few years ago we got a small flat roof recovered. The company just seem to have cut a chase into the wall it adjoins and laid felt about 6" up it over the existing roughcast and into the chase to serve as flashing, then mortared around the edges to seal it. There's no proper lead flashing. We just had the house re rendered and they've put a stop bead around where the felt was chased into the wall. The old render was stripped back to this point. There are two issues, the old render that remains under the felt flashing now makes it sit proud with a kind of gap at the sides. Second, the top of the felt is no longer able to go into the chase properly.
I suppose I need to put a proper flashing in, so can I just slot it in under the stop bead and put it down over the existing felt upstand. I was hoping to just use one of the aluminium flashings like this one rather than lead, would it be suitable:
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/152871816783
Would that work ok?

 

[doogyscoot]

 

[Alastairreid]

No reason why you cannot use the metal apron but it will need to be chased into the wall below the bead.

 

[doogyscoot]

So I've ordered the flashing and jammed a strip of rubber in there for now, hoping it'll keep the water out for a day or two. Is there any particular type of sealant I should use to seal the aluminium apron flashing into the chase?

 

[Alastairreid]

http://www.loctiteproducts.com/p/pl...PL-Roof-and-Flashing-Polyurethane-Sealant.htm

 

[datarebal]

ladders up the wrong way

 

[doogyscoot]

ladders up the wrong way

Not to worry, I'm not quite that daft, the ladders were just leaning against the wall when I took the pics. I had them the right way up when I was using them

Got the flashing sorted this afternoon. Glad I went with the preformed aluminium apron in the end. Cost £22 plus post and arrived next day. Lead would have been about £70 and taken a bit more buggering about.
It started raining half way through so the butyl sealant went on a bit less tidily than I'd have liked but it's all watertight.... at least I think it is, going by the forecast, I'll find out in the morning whether I'm right.
Before

After:

 

[Alastairreid]

Looking good.
That should do the trick.

 

[bobasd]

couple of things.youve fixed the the new flashing above the stop bead and the new flashing doesn look like its been chased into the wall.
i might be wrong but the old render dont look like its been hacked off so the new render seems to have been applied over the old render. a bellcast not a stop bead should have been fixed to throw water away from the flashing and upstand

 

[doogyscoot]

couple of things.youve fixed the the new flashing above the stop bead and the new flashing doesn look like its been chased into the wall.
i might be wrong but the old render dont look like its been hacked off so the new render seems to have been applied over the old render. a bellcast not a stop bead should have been fixed to throw water away from the flashing and upstand

The new flashing is fixed below the stop bead and goes into the old 25mm chase which I raked out, maybe just not that obvious in the pics. The L section of the flashing is 40mm deep so even though it's not flush to the wall it goes plenty deep. I agree that on reflection a bellcast bead would have been more sensible but that ship had already sailed before I got to this point.
The old render was stripped on the whole wall before the new render went on but only down to the edge of the flashing so it remained under the felt. The contractor who had replaced the roof felt a few years ago ran the felt upstand as a flashing up over existing roughcast into a new chase above an older chase. Not really ideal so I intended to strip the old render from under the felt upstand when I pulled it back. Unfortunately it was absolutely solid and with the second chase below already weakening the brickwork I was most likely going to wreck the bricks trying to get it off. I used mortar to fill the old chase and smooth the surface of the existing roughcast as much as I could and laid the upstand back over. There are a few aspects that are less than ideal but it should all be sound. The chase is thoroughly filled with sealant.