Hi Elizabeth, What size grate are you looking at? Most grate`s will vary by size on the surface but at the waste they are generally 40mm-50mm outlets. Tile will have no impact as the tiler will cut to angle the slope to the grate. if you are after fewer cuts i would suggest s channel grate.

has the concrete floor and drainage already been installed or are you still planning??

To add to the question above what grate will the builder supply?

i agree that the grate price does seem excessive...there are several on line shower grate companies that sell custom sized grates and invite direct contact for special sizes...why not try an independent quote to try and establish a base price or ask about alternative options...one company mentions a corner grate which could be worth considering...we were very happy with our custom size and service from Grates On line

do the three 1200 linear grates all drain into one waste hole?? and what is the purpose of the 1200 long grate in the laundry and 600 in guest bathroom? if they're all standard sized grates you should be paying less than $2000 for all of them... check on line ofr a base price and ask the builder to explain the difference?

Always worth checking, the builder quote could cover a few more things then just a grate it could include tilers extra fees for a shower base most tilers charge extra for a stepless shower base and it could cover screeding to form the fall in the shower base as well as the grate it self. Communication is the best cause of action here when my clients have a question I work at resolving any questions/concerns they would have, The builder should explain the cost to be clear you don`t want to feel like you are being taken for a ride the whole process should be open to communication this is key in all Renos & Builds