Flashing for lean to greenhouse

[DIY67]

I put this up a few years ago against wooden battens. I then added some black tar like stuff on a roll I got from Aldi or Lidl to act as flashing. Huge mistake! It only took one summer for it to shrink and persih creating holes. It's now a pig to get off, even with a scraper. The wall is also uneven as you can see. The wooden batten has rotted and water is leaking in badly. I purchased a roll of Soudal Butyband flashing on a roll some time ago but never got round to using it. As the weather is dry, can I just stick this over it or is there a better option like a piece of plastic I can fit that will only need sealant to make it watertight as I fear the flashing might look unsightly, especially as it has to be stick to the actual greenhouse metal ? Thanks

 

[Harry Bloomfield]

The wall is also uneven as you can see.

You would need that to be cleaned up, before trying to stick anything. Wearing eye-protection, and gloves - you could do it with an angle grinder, fitted with a wire brush, to clean it.

 

[DIY67]

I have been peeling it off with bare hands as I didn't think there was any risk.

 

[accelerator]

You need a much better design to prevent water flowing straight down the wall and into the wood. I don't know what the answer is but I can see why you've been having problems with the present design. It does need much better flashing. I would take a look at bay window roof designs to get some inspiration.

 

[DIY67]

Perhaps beveled mortar will do it ?

 

[accelerator]

My view - I was thinking some lightweight non-lead flashing. The flashing should come down off the wall, and then go over the top of the greenhouse for a few inches to ensure water runs off down the roof.

 

[DIY67]

Something like this perhaps ?

RSB-LTF — Aluminium Lean-To Flashing Profile

Alu Lean To Flashing Profile, EDGE Roof Systems RSB-LTF

edgebp.co.uk

 

[RrogerD]

You need to determine how rotten the wood is and replace if necessary, before attempting anything else. Otherwise, the whole lot will simply pull away at some later date.
From what I can tell from the pics, after attending to the wood, I would clean up the wall back to brick all along then, chase out a mortar joint and apply lead flashing along the whole lot. Pushing the flashing into the joint, affix with wedges, add sealant. On the plastic, be sure to have a decent overlap to ensure no water working it's way back up. I'd have thought a good 6-8" at least.
PS I'm not a roofer

 

[DIY67]

The trouble with lead flashing being that wide is it can't overlap too much as the window has to be able to open as well as slide out along the ridge for servicing, cleaning etc.

 

[StephenStephen]

The trouble with lead flashing being that wide is it can't overlap too much as the window has to be able to open as well as slide out along the ridge for servicing, cleaning etc.

Where's the window?

 

[DIY67]

Where's the window?

 

[StephenStephen]

If it was mine I"d replace the wood with a plastic plank, so it doesn't rot, then use stainless or decking screws to fix it.

Is water getting into the greenhouse a problem?