Laying slabs - with or without gaps?

[stoobloo]

What's best practice. I've noticed some patios and pathways have a few mm gap - filled with sand/cement. Some have the slabs butted up to each other with no gap.

Advantages of one way vs the other?

From experience our old patio which we inherited has 4-5mm gaps filled with cement/sand and it's nearly all failed and ant bubble up from between them!

 

[Odds]

I like a small gap between slabs for water run-off and helping moss to thrive, creating a patchwork of growth in what would otherwise become a stone desert. It all depends where the slabs are laid and the effect you wish to create. Place a bait trap (in fine weather) where the ants are thickest and they'll be gone in a day or two.