When laying paving slabs what is "butt Jointed"?

Answer 1

Butt Jointed simply means edge to edge with no mortar joint or gap between the slabs. Most concrete slabs are laid in this manner to facilitate movement between the slabs.

Ensure you lay a black geotextile membrane or thick black plastic about an inch below the slabs to help prevent weeds from coming through the joints.
Cheers

Answer 2

This means that the joints are in line, like a chess board, rather than staggered, like bricks.

Answer 3

laying in a pattern like bricks