If to quote an example - 20 sq mts of tiles were supplied and every tile was used, the job was complete and the wastage is off cuts from the middle of tiles, then the appropriate rate for 20sq mts should be charged.
It is not physically possible to fix 20+ mts of tiles when only 20 has been supplied. To charge more for cuts as full tiles and extra for cutting around windows etc. should be itemised in a estimate prior to commencing the job to allow the customer to compare prices on a like for like basis.
To try and charge more after the job is complete on the basis that has been originally described is unprofessional and unfair to the customer and other companies trying to compete for work.

if I'm supplied with 20m2 John, I'll use up as many off cuts with a clean edge that I can, if after that I've still handled and cut 20m2 of full tiles (inc cuts and clean off cuts) then that's what I'll charge for regardless of the degree of difficulty/awkward areas. If in that 20m2 there may still be a wastage of 10 percent say, that also is charged for.

I agree with most arguments regarding the rights and wrongs of charging for m2 fixed. But as stated above, the wastage should be Incorporated at the pricing stage ie, 5%, 10%, 15% depending on the size of the tile.

We all know as professionals it is near impossible to quantify a job down to the last tile, without setting a datum line and centering each wall/floor to give the most aesthetically pleasing effect.

If for example I am using a 600x600 tile, and to centre one wall to give equal cuts of lets say 450 either side, then I am wasting 150x 600, If I can use these off-cuts in the installation then I will.

In my opinion the 450x600 is a full tile, it has taken if anything more time to fix than a full tile, as it has had to be cut. Ergo. the amount of tiles handled/ fixed/ cut, should be charged for.

Again this should be allowed for in the pricing stage, I know a lot of quantity surveyors would disagree with me, but I am still fighting battles with certain QS's

im not sure if the op of this thread has been charged for over his amount bought if that is the case i think its wrong ie if he supplied 20 metres of tiles and has been charged for 23 if thats the case its wrong

but if he has been charged 20 metres on a 17 metre room size and the tilers used the full 20 metres the tiler is within his rights

would be nice if that could be clarified by the op

same as all the others - time taken in cutting etc is far more than just sticking a full tile up. My final invoice is what the estimate / quote was in the first place - unless extra work was required and price agreed before commencing that work. If the tiler has just increased their invoice with no discussions - challenge away.

Just my tuppence if the guy has said so much a m2 then he should have been able to give a final price before he started the job,i personally dont allow for tiles handled but do add on 10% for waste, hence if the job is 20 m2 i quote for 22m2 which is pretty much the same,but my invoices will state the exact figure i expect when the job is done,which will be the same as the one i have verbally agreed before commencing the job,as the o/p stated they have been charged for a wall that wasnt even tiled,cant see how anyone can justify that.