Gully lead set up?

[Draughtsman]

My gully was never put in correctly and has always been iffy, I'll have to bite the bullet and get it replaced. The run is long and has rolled joints when apparently it should have steps to accommodate sliding laps.

The lead is sat on a membrane (on top of ply) but I was wondering wether a membrane should really be be sandwiched between protective layers (geotextile?) to prevent membrane damage when the lead expands/contracts?

Thanks.

 

[Alastairreid]

Ideally geotec would be used but the membrane will suffice for a small area.

 

[Draughtsman]

It's about 12m long.

 

[Makie]

Do you have any pictures of the lead? If it is done correctly the membrane below it should not be an issue for you

 

[Draughtsman]

No images but I will get some.

It has a 25° conc. slate roof on one side and a vertical, rendered neighbours wall on the other, there's a lead skirt cut in along the base of the neighbours wall. There are 2 rolled joints in the 12m straight run of gully, one rolled joint has degraded so I recently sealed it with bitumastic, there is a membrane below the lead but it leaks. I think that the central section needs raising so that there are no rolled joints, only sliding laps to allow movement. I think that fixity is creating problems. In the past there have been problems with expansion pushing the lead up in ridges which eventually cracked.

 

[datarebal]

rings a bell this one. simply changing one section wont work for long...destine to fail.

do it properly,

check out calder guide to good leadwork