The Brew Cabin

Before we go and buy 3 tons of Kerridge Stone crazy paving flags, has anyone any advice on this type of stone?

What are you planning to do with the Kerridge stone? There's been a few problems with it on at least one job I know of, because of excessive mica causing delamination (it's flaking and falling apart, in layman's terms).

Is this new or reclaimed Kerridge?

Where can i get info on this crazy paving flag stone

This particular stone (ie: Kerridge) or stone for crazy paving in general?

Kerridge stone comes from a couple of quarries on the outskirts of Macclesfield and has been used for paving for over 500 years. Some of the original Kerridge stone is used in a dead famous cathedral somewhere down south - Winchester, p'raps, maybe Wells - I can't recall.

However, all natural stone varies through its quarry, and some of the 2001 Kerridge stone I've seen on a job in South Manchester is, literally, falling apart. It's not solely the fault of the stone; it's been badly laid, and some of it is ok, but it's not up to the job on this particular project.

For stone crazy paving it's usual to use a 'random rubble' paving stone, which means it is NOT trimmed into squares/rectangles, but is haphazard shapes. There's a page on the website dealing with the dubious joys of crazy paving - have you read that?

The stone is new from one of the quarries.
All the stuff I've looked at appears good quality.
I can understand how that delamination could occur, because of the variable thicknesses of some the layers.
The stonemason we're working with has never used this type before, but looking at the sample we've got, he reckons that with a decent bed (at least 30mm) we will remove potential problems.
We also are looking to use two part epoxy to bond the stone to a set of brick / wood steps, any known problems with this technique.
The main reason for choosing the crazy paving, rather than Yorkstone / Indian sandstone regular flags is that the path is basically an elongated 'S' shape, and will require large amounts of cutting to shape and the steps mentioned above will need a load of detail work for the flags. The decision came down to cost:
c. £10 m/2 for Kerridge crazy
c. £20 m/2 for Indian
c. £30 m/2 for Kerridge regular
Given the shape and design, we will have to throw about 30% of the regular stuff away!
Hence the choice of crazy paving.

Which quarry? Use the Messenger facility above, or email me, if you don't want to say in public. Not all of the Kerridge producers are members of the Stone Federation - make sure you get a written specification from the quarry that states the stone is suitable for the project.

The delamination we've witnessed occurs because of excessive amounts of mica. Water gets to the mica, causing it to expand, which, in turn, prises open the laminae of the stone.

I'm not sure an epoxy is the best way to bond this stone, or any riven-type stone, to the risers of steps. There is a lot of variation in unit thickness with a riven stone and epoxy isn't as good as mortar for taking up the differenmce between mis-sized adjacent units. If strength of bond is an issue, then I'd use a SBR-enhanced mortar rather than epoxy.
It's also highly likely that the epoxy:stone bond will be significantly stronger than the inter-laminae bonding of this type of stone, so, if there is any 'movement' it will result in the flagstone being ripped apart, rather than it coming loose from the bedding.

Here's a couple of pix....



The photo above shows the delamination adjacent to a 10p coin for scale, while the picture below shows the delamination viewed 'edge on' where it's been used for a poorly constructed step.



Note the abundance of mica (the sparkly, shiny particles on the surface) in the top photo. Is your stone like this?

It was the Kerridge stone Tony, thx for the answer

I don't think Kerridge travels as far north as you, als, but if you have a specific project in mind, I can put you in touch with the two major quarries.

Could you give me a hyperlink or e-mail address for any quarries in Scotland Tony?
Cheers Als

There's a few different types of stone used for paving in Scotland. Granite and Whinstone are popular, but you can get sandstones. I've just checked the Stone Suppliers Links page, and there's only one Scotttish Quarry listed, which means I'll have to update that a.s.a.p., but follow the links to the Stone Federation site or Stone-Mart and that will link you to more suppliers in your particular area.

You can get the imported Indian sandstone in Scotland, if price is more important than authenticity.