Sizes & Thickness differs with every lot. Each & every marble lot is cut into different block sizes so based on that lot the sizes are originated.
Once we get the final rectangular sizes from the civil contractor then the designer forms a grid pattern on the floor. Based on whatever size is available in that lot. So it’s basically like hand crafting rather than usual follow up of the regular size that’s available in tiles. In tiles you can control & get 600 by 600 size, meter by meter, 750 by 750 etc . That’s not the case with Italian Marble.
Each and every lot will have a different size of its own. Most lots are always Rectangular in shape, this way wastage is minimised. If the lot itself is of a weird shape like all the corners are being cut and maybe of a triangular shape then, there you might land up having more wastage.
Home Owner & Designer visits the store to select Italian marble. A good designer will not just see the sample piece but he will personally see to it that he/she measures each and every slab. This way overall square foot is being derived and then the client has to pay based on whatever sq foot area material is picked up. On paper each and every slab is being measured, each slab would have x no. of sq ft. and that is how you get the total.
Suppose I pickup 10 slabs so whatever sq foot 1 slab has is multiplied into number of slabs. And again whatever 1 or 2 slabs come in between might be of different size. Because they might have broken in transportation, so the size of those stones would be different. Based on that the overall square foot is being derived and the client has to pay based on that.
The designer will pin point which stone will go where, what will be the wastage, the overall quantity one has to buy and all such things. All these things will be basically a part of the designer.
Talking about Thickness, 18mm thick slab is ideal, the thickness that everyone should go for. But in India you also get marble which is 16mm thick. A Home Owner may not realize all that, it’s only an interior designer / contractor who can pinpoint all that. So you should always go through a good expert.
16mm is thinner so it won’t have that strength. 18mm is thicker so it will have that strength. It is better to go for a thicker slab since already it’s a softer marble. If you go for less thickness it’s a loss on client’s part.