Laminating York stone steps

[michael]

I have two flights of old York stone steps leading up to the front of my property, each flight has six steps. One or two of the treads are laminating i.e. small thin sheets of stone are detaching from the top surface or at least sound hollow and can be chiselled off with very little effort. My question is what causes this (water ingress and frost perhaps?) and can anything be done to stop it? I have noticed that the one or two affected treads are on the side of the steps that are shaded by a wall albeit not all the treads on this side are affected. Those treads that receive full sun are completely sound and unaffected.

 

[Flyfisher]

If not water freezing and thawing then perhaps differential heating from sun and shade?

 

[Penners]

I reckon all of the things listed by you and Flyfisher will be contributory factors. And, of course, every piece of stone will have different characteristics from every other, so some steps will tend to delaminate more than others.

 

[michael]

The lower flight of steps is about 8ft wide and the upper flight is about 12ft wide with a central hand rail. The width of each step is made up of 3ft lengths of York stone so the upper flight for example comprises of 4x3ft lengths on each step.
Three of the lengths which are fully exposed to sunlight are perfectly sound, and are able to dry very quickly after rain. The last 3ft length however (12 in total over 12 steps) is in the shade of a wall and more prone to moisture retention this is where the odd problem lies.
As the steps comprise of individual lengths of stone, I don’t think there is a differential heating situation across any one piece of stone. Quite simply three dry out quickly and one stays wet longer. Listening to your thoughts I believe it must be a combination of water and ice in the shaded damper area combined with the individual characteristics of each stone.
Can this delamination be stopped? Are there any stabilizing products on the market? Is there some kind of water repellent I could apply to the affected stones during the summer to stabilise them for the winter? On the affected stones I appear to be loosing about one layer per year.

 

[JoceAndChris]

I also have crumblage and delamination all over the place. I'm saving up for a product called "Stone Hardener" that Womersley's Limited do. It's £101.82 for one can, covering 10-15 sq m, though Mr Womersley has kindly offered me a 15% discount.

If anyone can give this product the thumbs up I will hand over my £101.82 with greater peace of mind. Otherwise, Michael, I'll let you know if it's done its job in a year or so!

 

[Penners]

I also have crumblage and delamination all over the place.

Oh, me too, dear - me too. And the ointment's not working....