Paving Laying Methods

Individual bedding
This method relies on each flag having a bed prepared for it individually. A bed is prepared, the flag is laid and then the next bed prepared and so on.
This method is more common used with larger flags, where handling and maneuverability is a major concern, with natural stone flags, where there can be differences in flag thickness between adjacent units. The flagstones should be laid directly onto to a mortar mix of 4 parts sand (class M) and 1 part cement approximately 20 - 40 mm thick. There must not be any voids under the slabs
Random thickness of natural stone flags makes screed bedding impractical
 
Screed Bedding
This method requires a screed bed to be prepared before placing the flags. A relatively large area can be screeded in advance and the flags placed one after the other directly onto the bed.
Whilst obviously more efficient than the individual bedding method, this method is only suitable for the smaller flags, generally those less than 600x600mm, which are small and light enough to be manhandled onto a screeded bed. It is essential that the flags be of a constant thickness, hence only the small element paving and wet-press manufactured patio flags are suitable candidates.
Regular thickness of Calibrated Brazilian flags makes screed bedding possible
 

Ground Preparation and sub-base

A sub-base is not normally required for a path or patio unless there is concern regarding the suitability of the sub-grade. However, any low spots can be filled with crushed hardcore, crushed stone or compacted bedding material. The surface needs to be dug off to a depth of approx. 90mm, assuming no sub-base is required. The depth of dig can be calculated as...

(average depth of flagstones + 35-50mm bed + any sub-base required)

For driveway or other heavy use, the sub-base layer is the load bearing layer. A full concrete bed (CBM4) is the best solution, combining sub-base and bedding in one and should be at least 100mm thick, minimum. For public footpaths, this may sometimes be reduced to 75mm, or increased to 150mm or more to give added protection to underground services

Individual bedding
Use a spade or large trowel to level out the bedding material, which should have the top 15-25mm loosened to allow the flag to be bedded down - this is usually achieved by 'rippling' the bedding surface, creating small troughs and peaks with the blade of a trowel. The bed should be 5-8mm high to allow for consolidation. Make the prepared bed spread 100mm or so further than the flag will cover - it is better to have the bed to big than too small, leaving an edge of the flag unsupported

Preparing an individual bed

Ideally, the bedding should be 25-50mm thick. Less than 25mm renders it almost impossible to settle the flag, while more than 50mm makes for uncertain compaction. Adjust the level of the sub-layers rather than use less than 25mm or more than 50mm of bedding.

Random Patterns

Please note for Sandstone and Travertine the random patterns may vary from those of slate. We endeavor to put more larger slabs in, as a proportion to make laying easier and reduce the number of Grout lines. Please advise if you need a particular pattern and we can quote you accordingly

Sealing

We recommend that all Sandstone, Quartzite, Travertine and Slate be sealed with an impregnator or similar. This will not only enhance colour and prevent staining, it will reduce water absorption and reduce incidence of algae growth

Picures and advice taken from website www.pavingexpert.com