Cast stone wall copings

[trevorbayliss]

I am going to be using some of these copings on a brick wall i am doing.

Do you know if i can lay then on a mortar mixed with SBR ? I was thinking this will make the mix stronger so i don't have any issues with the tops coming off.

 

[John D v2.0]

I would have thought gravity would hold them on. if not I think you can get some galvanised strapping to fix into the lower parts of the wall and run over the top, but I've no idea how you could make it look reasonable. Or you could drill into the bottom, insert some threaded bar and resin it in, then mortar that into the wall.

edit: ancon have just about every bit of shaped metal known to mankind, might be useful if you can get hold of them somewhere
https://www.ancon.co.uk/products/wall-ties-restraint-fixings/restraints-for-stone-cladding

 

[^woody^]

A "strong" mix, especially with SBR (which is pointless in mortar) will not mean that the mix has any more grip of the copings. In fact if its too inflexible then the bond will just break anyway as the wall expands and contacts normally.

 

[noseall]

expands and contacts

The demise of many a bedded coping.

 

[seasickstevie]

My gut feeling is that copings (and similar) usually fail because they're either not dampened first, or the mortar is left to partially dry out before bedding in.

 

[trevorbayliss]

Ok , so its a no to the SBR. Paving expert recons it is great in certain situations. He didn't talk about coping tops, but i thought it would be a useful addition after reading what he talked about.

Anyway can you all give me the best practise to lay my precast tops then ?

I will finish my wall tomorrow and then will order my pre cast stone tops.

So do i hose down the wall about 30 mins before putting the tops on ?

I have been using a cement / lime / sand mix for my mortar for the wall. Do i just use a similar mix. I have been doing 5/1/1 for the mortar.

Is a wetter mix better for the tops ?

Thanks for the help

 

[John D v2.0]

I'm no expert on copings. However, but the general principle for bedding anything would be to provide stable even support over a wide area, and the weight of whatever is on top will keep it in place. Using any kind of adhesive would have negligable effect. Maybe on a scratch coat of render over the large area it would help, but when laying 10kg+ coping stones maybe not.
On that basis I'd use a normal 5:1 mix, don't make it any wetter than you need to, and make sure you get it to the edges and tap the stones down to make a good supporting base.
However, see my first sentence of this post.

 

[trevorbayliss]

The link to ancon shows a few easy to use metal pieces.

The weather will not move them. It is potential vandalism which means fixing them a bit more securely could be useful.

 

[trevorbayliss]

Have just watched a Utube vid on copings.

What about using a cement slurry painted onto the brick base first and the underside of the coping ? then you place your full bed of mortar.

What do people think about this technique ? Would it be ok with a cast stone ?

 

[^woody^]

All you need is two clean, dust and loose-stuff free surfaces, which are slightly dampened, and some good 3 or 4 and 1 mortar (which may also benefit from being 75% building sand and 25% sharp sand) and full beds (with any frogs and joints filled) and the bed laid with enough mortar to allow you to give a good tap down and twist/slide the copings back and forth when laying - that's the most important bit. Mortar as wet as you used (or should have used) for the rest of the wall.

Point up when the joints are firm and press well and iron the joints smooth. Joints should be full.

In this weather, cover in polythene or damp hessian for a week or so, and don't lay these in hot direct sun. Wait for a cloudy day or do these early or late in the day.

 

[trevorbayliss]

Thanks woody for the useful info.

Noted about laying in the sun.

I have been doing the bricks in the sun. So been making the mortar a bit wetter.

Do you think I should hose the wall with water in the eve for a few days or will this not make any difference?

 

[John D v2.0]

Mortar shrinks when it loses water so avoid adding too much and avoid it drying quickly as woody says. Too much cement can also shrink and too small aggregate presumably why he suggests sheep ands. I wouldn't hose it for a couple of days, normally i use a mist sprayer to spray the Hessian but not running off. If you hose it the same day you can wash cement out.

 

[^woody^]

No José.

You risk creating efflorescence by wetting a wall after just laying.

 

[trevorbayliss]

Thanks all again