What is staining this wall. the lead or the coping stones?

[suggett1976]

I have been asked to look at a couple of walls which have heavy staining and some paint pealing.

There are run marks coming from above the lead.

The painter has had a specialist from the paint manufacture come out to look at it and they have come to the decision that the moisture in the coping stones is running over the lead and the lead is staining the wall.

I'm not so sure,

I was wondering if the salts etc in the coping stones are bleeding out.
The stones are around 15 years old and are very porous. They hold a lot of water.
When you look closely at the sand/cement that the stones are set on, you can also see some slight staining.

The coping stones were treated last summer with a moisture repellant, but this hasn’t worked.
The coping stones are so wet that you can scratch the surface with screwdriver without much pressure as they are very soft.

I have been asked to remove the coping stones, remove the lead and replace with a rubber or bitumen membrane then reset the coping stones.
I wonder whether it’s worth replacing the coping stones at the same time.

Untitled

• suggett1976
• 25 Oct 2010
• 1

Untitled

• suggett1976
• 25 Oct 2010
• 1

 

[^woody^]

Looks like iron [pyrites] staining from agregates within the copings, and not from the lead

 

[Nige F]

Tell me where in Sussex - I`ll take all that lead for you - Free . If you fixed a square batten under the lead so it didn`t lay close to the wall - the water and dissolved salts would not stain / run down the wall . That too, is Free advice

 

[suggett1976]

Free advice and free lead. Can't be bad.

Thanks guy's. I had a feeling it was salts or iron etc
The battern under the lead could be a good temporary option. However i feel it could be time to change the coping stones, its just a decision whether to remove the lead or not.

Whats the chances of the new coping stones doing the same thing?

 

[Nige F]

probably quite high ,eventually . but leave the lead just give it a coat of bitumen paint to stop the new mortar corroding it when the slabs are laid . It`s a better DPC than anything else

 

[suggett1976]

Thanks.
The customer has decided she wants rid of the lead and replace the coping stones.
Who am I to disagree.


Is there a good product I could coat the coping stones in to stop the being so pourus.

 

[Nige F]

Thompson`s water seal poured some on the flaunching round my chimney pot - stopped the penetrating water a treat. BUT it, and most other sealers will probably react / dilute the lead substitute the customer wants - and you may have even more mess down the wall . Rubber membrane would probably be better - but you need to go carefully on this one . Best option , uncover the lead , kill any security lighting , let me have the postcode for the satnav in the transit pickup

 

[phil5366]

Try some patonation oil on the lead. Most builders never use this to coat lead flashings, etc. We have to use this all the time when working with lead as it is specified by the Architects.