Rubble Filled Wall...repointing??

[Penners]

What this thread proves (if proof were needed) is that different parts of the country have developed different variations of traditional building techniques. Hardly surprising, really. And the strong probability is that the local technique is the best to go with. It will have been developed over hundreds of years to suit the local materials and environment.

 

[Anonymous]

...The term "key binder" is meaning I think, the stuff to bind the sand grains together, not to bind the wall together.

It is the grout that binds the stonework together. And do not assume that through stones are always present in a solid stone wall. We recently inspected a 19th Century field barn where the inner and outer skins had separated and most of the inner face had collapsed. There was not a single through stone to be seen.

 

[Anonymous]

What this thread proves (if proof were needed) is that different parts of the country have developed different variations of traditional building techniques. Hardly surprising, really. And the strong probability is that the local technique is the best to go with. It will have been developed over hundreds of years to suit the local materials and environment.

Hear, hear.
If you go back to the beginning of this thread the discussion concerning the use of grout only arose as a possible repair technique.

 

[chuckey]

I have talked to quite a few locals about "heartings". None of them (3 builders + 3 other quite clever chaps) have come out with any technical reason for them, indeed the concensus seems to be this is a good place to put ones rubbish. No one ever has or does fill the "cavity" with mortar, unless its rubbish and needs to be got rid of.
Throughs again are marginal because of their cross section they put cold spots on the inner skin of the wall and unless installed properly they can catch water which pools up and then finds its way through into the room. They again catch dirt which makes their top surface water holding which defeats the point of two skins.
As for heartings in general, imagine an outer and inner skin of a wall made with more or less ball bearings glued together, filling the cavity with more ball bearings will bulge the skins, leading to premature failure.
Frank

 

[Penners]

Except, of course, that bits of stone are different from ball bearings in a number of significant ways.

Try doing this with ball bearings:

No, I'm not being flippant (you'll be surprised to learn). The friction that exists between pieces of piled stone is very important in the context of heartings/infill/dross - call it what you will.

 

[Anonymous]

...As for heartings in general, imagine an outer and inner skin of a wall made with more or less ball bearings glued together, filling the cavity with more ball bearings will bulge the skins, leading to premature failure.

Exactly. When this separation occurs a non-intrusive repair repair technique needs to be adopted if the wall is to be stabilised, rather than reconstructed. A common solution in such circumstances would be to insert the HELIFIX ties I mentioned earlier to reinstate the bond between the inner and outer skins. However, the ties alone are not sufficient to afford structural stability which is why a hydraulic lime grout has to be introduced to fill the voids. We have been designing and specifying this repair technique on Listed historic buildings throughout the north of England for many years and it has proved to be successful.

 

[Schoolmarm]

Except, of course, that bits of stone are different from ball bearings in a number of significant ways.

The friction that exists between pieces of piled stone is very important in the context of heartings/infill/dross - call it what you will.

Indeedy. And heartings were never meant to be heaps of dross in the middle, rather they should be small carefully placed stones to fill the void perfectly.

Anyway there appears to be some confusion arising between walls of a building and garden/field walls.

And I still disagree about the meaning, in that context, of the word "binder".

 

[Schoolmarm]

It is the grout that binds the stonework together.

Then why are Helifix necessary and being suggested to stop leans, bulges etc.? If it was so good at "sticking two skins together" there would be no need for anything else.
I understood that lime keeps stones and bricks apart and doesn't stick them together.

 

[stuart45]

The reason why a fireback cracks is that it hasn't been installed correctly. Before fitting a layer of cardboard should be taped across the rear face of the fireback before the rubble fill is put in. When the fire is lit the card will char away over time, thus leaving a small gap which accommodates expansion and contraction. This gap limits the likelihood of cracking.
.

It's many years since I used rubble for a fireback. Nowadays a weak mix of cement/vermiculite is preferred. Corrugated cardboard is still used. If rubble is used it still needs to be stabalised with lime mortar as it will still settle in time against the fireback and increase the chance of cracking when it expands.

 

[OliveTree]

It's many years since I used rubble for a fireback. Nowadays a weak mix of cement/vermiculite is preferred. Corrugated cardboard is still used. If rubble is used it still needs to be stabalised with lime mortar as it will still settle in time against the fireback and increase the chance of cracking when it expands.

@stuart45 when did vermiculite start being used to backfill a fireback?