Paving

A lot depends on what is underneath soil wise.

If clay, use a pretty fair base of rubble, limestone or what have you, because it shrinks in summer alarmingly.

Personally I then laid on a very WET later of sand and cement - sharp sand - because I was laying unequal thickness sandstone. I needed to tamp each one down.

If you are using machine made slabs, a dry mix laid flat first is a lot quicker.

The theory behind the cement is that it stabilises the sand which won't then wash away.

Or get redistributed by ants

Indeed: it is wise to contain the sand at the edges by either kerbstones of some sort, or as I did with my patio, concrete.

Actually I used a 3" concrete foundation on 2" or so of sand, so all I did at the edges was use 6" of concrete to keep the sand in. The advantage of a concrete bed is that the slabs don't crack/settle over time and you don't get weeds either.

If you go for sand alone, do use a geotextile sandwiched between two layers of sand to discourage the weeds.

Andy.

This all depends on what is there now, it cannot be answered until it is known.

If the land to be paved is already covered with concrete / tarmac / paving, then 50mm of dry sand and cement is adequate, if it's loose soil in flowerbeds, then this is going to sink, so it needs to come out now and filled with crush and run, likewise if you are removing a section of lawn...if the ground is firm, use S&C, if not use hard core first, then S&C.

The easiest way to get it right is to trammel it with a dry mix, then lay each flag gently down flat on it and giveit a few taps in the centre to bed it in, don't walk on any til the next day.

The only way of making sure that the slabs stay put is to lay them on a mortar mix. Providing the ground under the mortar is firm you shouldn't need hardcore for a light use patio area. But if the soil is soft then you probably need a sub-base of compacted rubble.

If you just lay them on sand then you may get tilting and rocking later.