The Brew Cabin

Hi, I'm laying a patio with 500 X 250 slabs (flags), and I've read that the standard spacing between them should be about 9mm for the mortaring. However, I've just placed a couple of slabs together on the grass to check, and the edges are bevelled, which means that although the slabs touch each other at the bottom, they are between 5 - 10mm apart near the top. (The slabs are about 45mm thick.) Also, the edges are not perfectly straight, but have a more random, natural look - which is why there's a variation between 5-10mm. So my question is - should there be a 9mm gap between the bottom of the slabs (which will result in an unsightly large 15-20mm gap the surface), or should I join the slabs as close together at the bottom?
I hope I've explained this OK?! Please help! I;m starting the proper laying this FRiday (17th).

Many thanks.

10-12mm is the usual joint width, even with irregular flags. It's not desperately critical, but, if you're using mortar joints, adjacent flags shouldn't touch and you can have a joint up to 20mm or more, although the bigger the joint, the worse they look. If you can keep them all around 10-15mm wide at the surface, they'll be fine. :)

Good luck for Friday - let us know how you get on.