lead flashing, replacement.

[Grenage]

Hi there,

There's a small porch extension on our back door, which started leaking against the wall. Inspection of the small roof shows a crack running most of the length of the sealant, which is on top of the flashing seal.

I temporarily patched it with some sealant, but it clearly needs redoing; I didn't think flashing even required sealant, and that was rather the whole point of three stuff.

It's a short run, so the flashing would only cost about 40 quid. Looking online at guides, it seems fairly simple:

Rip out old stuff, and mortar along the run.
Replace flashing and secure in place with some folded lead pieces.
Tap down flush against the wall and tiles.
Replace mortar.

Seems almost too simple, am I missing anything?

 

[yorkie1969]

Lead epands and contracts, mortar does not. Lead sealant has more give than mortar. Sealant never falls out, if you use the corect one and you do it properly.
Almost too easy? Sounds like someone has fluffed it up!

 

[catlad]

No just replace like for like, if its longer than 6' then cut it in half and overlap by 5 or 6" it might be easier to use lead seal than cement depending on how wide the gap is.

 

[Blagard]

Hi there,

There's a small porch extension on our back door, which started leaking against the wall. Inspection of the small roof shows a crack running most of the length of the sealant, which is on top of the flashing seal.

I temporarily patched it with some sealant, but it clearly needs redoing; I didn't think flashing even required sealant, and that was rather the whole point of three stuff.

It's a short run, so the flashing would only cost about 40 quid. Looking online at guides, it seems fairly simple:

Rip out old stuff, and mortar along the run.
Replace flashing and secure in place with some folded lead pieces.
Tap down flush against the wall and tiles.
Replace mortar.

Seems almost too simple, am I missing anything?

While it could be the flashing that is the source of the leak, if the roof is a flat one I would be looking very hard at the roof finish where it joins the wall.

 

[Grenage]

Hi chaps; thank you for your replies.

It's a pitched roof, so I'm pretty confident it's the flashing. It looks a bit messy, so pulling it all out and starting again is probably the best way to go. Given that it's a short run, the lead won't cost too much. Going by the above:

I'll rake out the existing stuff.
Use 240mm Code 4 lead flashing.
Repoint with flashing sealant rather than mortar.

Thanks!