How is leading/felt done at rear of chimney?

[ClockPie]

Chimney, with sloping roof to the back of it.

Lead saddle around. Tiles overlap rear of saddle.

Under tiles is waterproof membrane. Where does this go?
- Over the lead (such that water on the membrane runs onto the lead and off.
- Under the lead (such that water on the membrane goes under the lead and, err, then what?

I ask as I have a leak at rear and found this pic from 2y ago (scaffolding not here yet) and to UNTRAINED EYES it looks like bottom right there are a couple of routes water can get under the lead, my the triangle or where the rear overlaps the side. Perhaps there there should be a another part tile overhanging there, but then where is the membrane? If thats in the roof under the lead, then any leak further up the roof will come out in the loft.

Wondering what is right so I can ensure its fixed correctly

I ask as a

 

[ClockPie]

Any pics or pointers to how this should done before the tiles are replaced would be fantastic

 

[noseall]

Any pics or pointers to how this should done before the tiles are replaced would be fantastic

 

[ClockPie]

View attachment 374441
View attachment 374442

Perfect

But where does/should the roofing membrane go? Over the sloping lip at the rear I assume? Rather than under? My pic *appears* to show some "top edge" of the lead suggesting the membrane goes under (which feels wrong)

Won't know till I look in a day or two

 

[noseall]

Perfect

But where does/should the roofing membrane go? Over the sloping lip at the rear I assume? Rather than under? My pic *appears* to show some "top edge" of the lead suggesting the membrane goes under (which feels wrong)

Won't know till I look in a day or two

The membrane ideally (if the lap allows), should drape on top of the back gutter upslope tray.

 

[ClockPie]

The membrane ideally (if the lap allows), should drape on top of the back gutter upslope tray.

Thats logical. But I'd have expected to see it in my pic above? Will find out and see what I see in teh next couple of days.

If membrane doesn't overlap I guess I'll have to install a sheet of lead or something to go under the membrane and over the existing led (saddle?)...!

 

[noseall]

Thats logical. But I'd have expected to see it in my pic above? Will find out and see what I see in teh next couple of days.

If membrane doesn't overlap I guess I'll have to install a sheet of lead or something to go under the membrane and over the existing led (saddle?)...!

You can arrange the roofing membrane so that it will deflect from around the back of the chimney, with some clever draping of the membrane, around and on top of the back gutter tray. If lapping on top of the back gutter lad tray is an issue, just make sure that any rainwater by-passing the lead, falls either side of the chimney, via thoughtfully arranged membrane.