workmanship has to be conducive to offering a product or service that is fit for purpose and remains so for a "reasonable" period.
In terms of statutory rights of customers it make little or no difference what term of guarantee you put on either workmanship or the materials. As a supplier of a specialist product and/or service you have to ensure that the resulting work conforms to what a court would deem to be reasonable.
In terms of tiling being a semi permanent fixture I would have thought a reasonable term would be very very considerably longer than 1 year. If I spent several thousands of pounds on a tiled floor and it failed after little more than 12 months I would have no hesitation but to insist the tiler sorted it out.
I do know that when I supply screeds by implication they have to offer a life expectancy to conform to the reasonable life of the building. I have had to write guarantees in the past for anything from 12 years (
Standard PFI snagging term) and 100 years (standard design life for domestic dwellings)
I think I would be a bit insulted and indeed put off my a tiler who was telling me his workmanship and if appropriate his materials were only likely to last 1 year.