Is this too long

[padstar]

I have a 6m wide kitchen with a 2m wide utility next to it.

We are laying 900x600x15 limestone floor tiles to both. I understand 6m is acceptable and won't have issues with expansion but do I need to install an expansion joint at the door threshold or can the tiles run through the door meaning that 1-2 rows of tiles will be 8m long?

 

[curry-kid]

You don't need expansion joints for stone flooring. I have slate tiles all through our downstairs, with the longest run being 8m. I did mine in phases with the oldest down about 4 years now. I used a decoupling membrane (you mentioned you will use one in another thread) and have had no problem with the tiles. Our tiles are in the hallway (L shaped), downstairs toilet, dining room and an area in the living room (to the "back door" - converted barn so strange layout!). When we get the money for the kitchen, we will take the same tiles through into there as well.
It looks nice when the tiles run through from one room to the next.

Do use flexible tile adhesive though. Along with the decoupling mat that will provide enough "give" if the floor moves a bit.