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How to cope with coping stones


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I've done exactly what you're advocating, that is got the packers level and CT1'd in place. Then slopped the mortar on. Put the "stones" on and they will only bed as far as the packers.

 

Just can't recall where I used the technique.

 

Not sure if shrinkage will be an issue as mortar/ concrete shrinks back a bit I believe. 

 

 

Edited by Onoff
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20 minutes ago, Onoff said:

I've done exactly what you're advocating, that is got the packers level and CT1'd in place. Then slopped the mortar on. Put the "stones" on and they will only bed as far as the packers.

 

Just can't recall where I used the technique.

 

Not sure if shrinkage will be an issue as mortar/ concrete shrinks back a bit I believe. 

 

 

Tempted to do this . Let the cement cure for a bit and then just a few lines of grip fill on the cement . Then bed it .

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41 minutes ago, pocster said:

Tempted to do this . Let the cement cure for a bit and then just a few lines of grip fill on the cement . Then bed it .

 

Personally I'd only bed them on a full mortar bed. Heavily laden with SBR. I'd then pipe the joints with the same stuff.

 

Do it properly or water will get under them, freeze, expand and loosen them over not too long a time. 

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1 hour ago, Adsibob said:

Can you hide the wall by raising the floor level either side of it by the height of the wall. Then you will really show off your coping stones.

I wanted to type (expletive deleted) off ; but I couldn’t 

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3 hours ago, Onoff said:

Not sure if shrinkage will be an issue as mortar/ concrete shrinks back a bit I believe. 

 

That's why you really don't want it 'grounding out' on something solid. The same applies to brick/block/stone - your building units can then become loose after the mortar has cured.

 

There is one little 'trick' that springs to mind though - if you're whacking something down to a level on a full bed and you overdo it, then usually you just have to take it on the chin and lift off and redo the bed. But because the muck is hydraulic, i.e. incompressible, you can sometimes hammer-in a strip of plywood or something a bit narrower than the bed thickness (and the same width as what you're lifting) as a drift which will force the mortar to bunch-up and push up the thing that needs lifting at one edge.

 

You definitely don't want to just lever it up as that will create voids but having it being pushed up by the mortar is fine. At a given point though, if you've squeezed all the water out, it will just lock-up solid. If it does work you can then pull out the drift and point in the gap you made at the edge. I've often done this successfully with heavy concrete patio slabs but you'll certainly need a big old lump hammer to persuade your bigger stones. Go careful!

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Taking all the advice and suggestions I had a brief moment of brilliance!

The issues are the bed being flat and the fact copings don’t particularly stick well to concrete.

So ! . Rebar rods down each side that are dead level , packers if need be .Cement them in and fill any holes with cement . SBR on the existing base . Then concrete again along the middle using the rebar rods as a definitive level I.e drag a piece of timber along them .

Should get a guaranteed level .

3 lines of grip fill and just place coping on . No fumbling with packing , cement dropping etc. 
This is THE solution !

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Rebar bars dead level

 

0CB5F070-8FBB-40C7-A4CA-30A56EDDCC63.thumb.jpeg.c3dbf3ad16200e800699d1a080d08879.jpeg

 

Cement rather than foam as too breezy .

 

 

Leave to cure for a bit then SBR . A non stiff cement mix . Tap it in using the rebar as my guide . Perfecto ! ( in theory ) 

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5 hours ago, pocster said:

3 lines of grip fill and just place coping on


Not unless the concrete has dried for at least 30 days and you’ve kept it dry too as it will just pull off. What’s wrong with using an SBR mortar mix ..??

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34 minutes ago, PeterW said:


Not unless the concrete has dried for at least 30 days and you’ve kept it dry too as it will just pull off. What’s wrong with using an SBR mortar mix ..??

Nothing - but it would have to be a super thin bed . The coping stones don’t exactly stick well to mortar in my experience. What’s wrong with an adhesive ?

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8 minutes ago, pocster said:

Oi ! You said you packed and glued with ct1 !

 

Erm...no, I said I'd glued the packs on with CT1 then slopped mortar on so the stones/blocks "sank" only as far as the packs. I then went onto say about possible shrinkage.

 

Remembered where it was now, doing my gate pillar caps.

 

IMG_20210731_161542640

 

IMG_20210731_161658840

 

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8 minutes ago, pocster said:

Nothing - but it would have to be a super thin bed . The coping stones don’t exactly stick well to mortar in my experience. What’s wrong with an adhesive ?


Could be because you’re using the wrong type of mortar or not pre-priming etc..? I bed them on to 5/1/0.5 sand cement lime with a waterproofing admix and they don’t move anywhere. 

 

Gun adhesives are not designed for this sort of situation - you need a full width bed under the coping stones or they will just pull free. 

 

If you want a thin set full bed adhesive for these then this stuff is good - will work well with your concrete infil as will mechanically bond also. 
 

https://www.homebase.co.uk/norcros-rock-tite-outdoor-tile-mortar-25kg/13628420.html

 

 

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Just now, Onoff said:

 

Erm...no, I said I'd glued the packs on with CT1 then slopped mortar on so the stones/blocks "sank" only as far as the packs. I then went onto say about possible shrinkage.

 

Remembered where it was now, doing my gate pillar caps.

 

IMG_20210731_161542640

 

IMG_20210731_161658840

 

The problem as as you say they could just be sat on the packers not even bonded to the base . 

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3 minutes ago, pocster said:

The problem as as you say they could just be sat on the packers not even bonded to the base . 

 

I don't think in this instance it'll be a huge issue. Tbh though as long as your mortar mix isn't too sloppy you should be able to bed them in dead straight and level without packs, tapping down here and there. That's how a proper bricky or most of here would do it. Mortar squidges out and you just run a tool along like I did above.

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55 minutes ago, Onoff said:

That's how a proper bricky

The same brickies that know nothing about airtightness, and usually get the window openings wrong.

 

Quite impressed with @pocster's solution, quick and easy, and he had the rebar kicking about (cause he ain't got a clue how to use a tape measure yet, the final coping stone won't fit).

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