Crumbling slabs! - Lonstone garden stone

[Nick J]

Got another problem, probably due to the weather, a client called me back to a job that I completed about a year and a half ago complaining about disintegrating slabs.

The slabs in question are a Lonstone product, the Garden Stone range. We had a look at them and they are indeed crumbling around the edges, and kind of flaking off on the tops. Nearly all the slabs are affected in some way.

Anyone come across this phenomenon before?

[GB_Groundworks]

on a patio or driveway,

if they are on a patio address the problem to the supplier/manufacturer

if they are on a drive where they fit for purpose?

[Nick J]

They were laid as topping on a flight of outside steps that I built. (Concrete steps, mortared down slabs on a solid base of 5:1 sand & cement, slabs pointed with 3:1 sand & cement, the slabs are very well laid and solid!)

The supplier had informed me that they were fit for this purpose. My problem is that the supplier, like many out there, has wound up. Looks like it will be photos and a letter to Lonstone.

I guess the point of this post is that, in 15 years in the trade, this has never happened to me before, so I was wondering if any of the more experienced paving contractors out there had ever come across the same defect. Perhaps my experience could be a warning to others?

[Tony McC]

If it is a problem with the flags themselves, I'm sure Lonstone will do whatever they can to help you. They are one of the most friendly and accommodating manufacturers I've ever dealt with.

However, check with the client first: have they been dousing the area in salt or, even worse, de-icing salts? Certain products can literally rot some forms of wet-cast concrete, so check before calling in Lonstone. It's always a good idea to be fully aware of everything the client has or hasn't done before calling in a manufacturer as their brief is, understandably, to find some event or incident or treatment that removes their obligation and responsibility.

[TheVictorianCobbleCo]

Tony's comments re salting are important, as is what have the slabs been cleaned with, etc. If they've been washed with a too strong acid wash, the surfaces will erode. My addition tho, is once I made 10000 cobbles for a clients driveway, about 20% started crumbling within weeks of being laid, after MUCH enquiry, it transpired that I' d been given a duff load of sand, very little comeback, and expensive.