Coping stones round balcony parapet..double or single weathered

[Tingly]

I am having some coping stones fitted around a parapet wall around a balcony.( we have had a bit of weather based water ingress last year)
Am wondering if double weathered or single would be best...ie would the double make the rain go down outside of the wall and cause more trouble there?
Also are the 50 ml with 75 ml apex really deep enough? Or do i need deeper.
Thanks

 

[^woody^]

Either will do its just down to how thay look. The main thing is that they overhang the wall by at least 50mm each side and have a drip formed underneath to allow water to be dripped away from the wall

And are DPC's and cavity trays in place?

 

[Tingly]

Thanks. Not sure what a cavity tray is? Dpc there though.

 

[Tingly]

Ps just looked them up...looked like cardboard? Can the be placed over engineering bricks and under the coping stones we are adding?

 

[Tingly]

Plus....the dpc is at the bottom of the wall at ground level. So the situ we have at the moment is parapet wall, adding coping stones (after new balc floor laid) plus painting of weathershield on outside. The question is...do we put (or ask the roofer) to put something between the engineering bricks and the new copers?

 

[^woody^]

There should be a DPC in that parapet above the flashing, and another below the copings, not just at ground level!

It does not look like a cavity wall, so no trays required.

 

[Tingly]

Thanks Woody. Bugger...too late for that now then...without reconstruction of whole wall.