Help with limestone flags as coping

[Whiplikeflagella]

Hi folks,

I have a brick wall with natural black limestone flags as coping. The flags hang over the wall by about an inch.

The builder has set them twice with mortar but when you lean on them they move so not set properly.

Do I just need to set them again with a stronger cement mix or is there a trick to setting natural stone on top of a wall that can stand someone leaning on the flag?

cheers.

[Al Jardin]

Hello Whip
Make sure the mortar is a strong sharp sand mix and not soft sand. Something like 3 or 4 parts sharp to 1 part cement. Add some SBR in the mortar when you mix it. Also make a slurry of 1 part SBR to 1 part cement. Cement goes into a jar or container first then add the SBR a little at a time while mixing until you get a thin light grey paste. Pre wet the underside of the coping to take the edge off the stones thirst. Apply the slurry once the coping has dried a little but not fully. Don't paint to the very edges - keep back by 30-40mm or so. Set, level and leave.
Other members may have a say in regards the stone & cement type.

Good luck.
Al

[lutonlagerlout]

btw whip i take it you have cut drips to the undersides of these copings?
LLL

[Whiplikeflagella]

Thanks Al - much appreciated. I'll give this a try.

@lutonlagerlout - Hi - sorry for my ignorance, I'm trying to fix something the builder did. The flags are just as they came, so flat on the underside. Not sure what you mean exactly, but are you suggesting I need to score them underneath before laying the flags as coping?

cheers.

[lutonlagerlout]

for a coping to shed water efficiently it must have a drip
http://www.google.com/url?sa=....2287654
like that
if it doesnt water tends to run under and down the face of the wall
ruining the wall over time
LLL

[Whiplikeflagella]

Thanks LLL, this make sense. The builder didn't do this when he layed them originally so I'll have to cut them in before I re-lay.

Thanks again.