The most noticeable trend in customer's requests for house staircase designs in recent years is for glass treads and or glass balustrading. I am not sure what kicked off this trend, but I suspect that it has a lot to do with house makeover programmes on the TV. Whatever the cause it is flavour of the month, and I suspect it will run for a little time yet.
If you stop and think about it, you would be hard pressed to think of a less suitable material for staircase treads than glass. In its basic form glass breaks, it has a banana skin slippy surface, and from the engineering standpoint it is a nightmare to shape and to fix to other materials. OK modern technology allows us to overcome these things to a certain degree, but we are still pushing the bounds of feasibility.
Don't get me wrong even an old codger like me can see the style and wow factor in a glass staircase. I also need to point out that my concerns are mainly over glass staircase treads, glass balustrading on the other hand has long been used commercially, it looks good and any engineering problems have long been solved.
So let me give you my personal viewpoint on the pros and cons of using glass in your new dream spiral stair or flight staircase. Then no more snide comments from me, you can decide for yourself

THE PLUS POINTS
1.Glass in both treads and balustrade looks superb and gives the ultimate see through minimalist look.
2.Glass is actually a very hard and strong material capable of wiithstanding lots of wear and tear.
3.Combinations of laminating, toughening and etching the surface can overcome the safety issues usually assoiciated with brittle razor sharp material like glass.
4.Glass staircases allow light to pass through, opening up those dark corners and creating a feeling of space.

THE MINUS POINTS
1. It is seriously expensive material to use in staircase construction. Do not even contemplate it unless you are a banker or have a Member of Parliament expense account.
2.Despite its strength it can be chipped or worse a toughened unit can shatter if your plumber drops his wrench on it while drinking his tenth cup of tea. This is an expensive material to repair or replace, and with a spiral stair you would probably have to dismantle the whole stair staircase.
3.Without an etched surface it can be slippy, the Building regulations do not like that.
4.There are very few glass tread stair systems that allow for a balustrade system that complies with the Building Regulations 100mm sphere rule (see earlier blogs). This is particularly relevant to spiral staircases because it is almost impossible to use a vertical baluster system (they need too many holes in the tread for it to work with glass).
5.Glass is heavy and the extra loading on the structure needs to be considered with both landing balustrading and staircases, particularly spiral staircases.
6.Wearing knickers becomes compulsory whenever you use the stair.

There are stair systems around that can overcome the downsides, but always check their suitability for both your project and your purse before you get too excited over the prospect.