Fitting coping stones to a parapet wall

[goodbyegti]

I have capped my parapet wall in code 5 lead. Under the lead I have building paper, osb3 and then a cavity tray with weep vents.

 

To finish I have some cast concrete coping stones, which will give a 50mm overhang on both sides, with drip channels. I have GRP on one side, and surecav on the other.

 

I am trying to make it leak proof for many years. Have I missing anything?

 

To fit the coping stones, should I put a layer of bitumen paint, or silicone a DPC on? The main reason would be to prevent the cement reacting with the lead. But I was also thinking about thermal movement of the lead which the DPC could perhaps help with.

 

For the mortar, would you go for a  3:1 mix as per NHBC guidelines? Is it worth putting fibres in, or some mesh?

 

Edited July 5 by goodbyegti
typo

[nod]

I simply lapped the fibreglass over the plywood’s that I’d fitted over the cavity Then laid the copings on mortar 

[Dave Jones]

dont put anything over that lead it looks great as it is.

[goodbyegti]

[goodbyegti]

Both good suggestions. GRP over the top would have given me a problem wrapping over the stone on the other side. I did like the lead on its own, but keen to get a drip channel on the coping to keep the water off the wall.

 

In the end, I had some Resitrix primer left over, and that stuck to the lead nicely. So there's synthetic rubber between the mortar now. Probably overkill!

[goodbyegti]

From the other side.