Laying Guidelines

Efflorescence is a natural phenomenon and can occur in all natural paving products. It shows as white patches on the surface of the slabs. The efflorescence may occur each time the paving dries after rain. This may re-occur for up to 18 to 24 months. Efflorescence will cease once the calcium carbonate completely leaves the stone.

Natural stone products have variation in colour so select paving from a number of open packs to ensure an even blend. Where possible start with full flags being laid adjacent to a fixed point such as building or edging.

Set the required level using a taut line. Tap each slab down to the appropriate level using a rubber mallet and also use a spirit level to double check levels with the adjacent slabs. It can be helpful to 'butter' the edges of previous slabs - being careful to maintain 10mm - 15mm between the slabs.

To butter the previous slabs - trowel mortar onto their edges so that when the next slab is offered up, the mortar compresses and rises up between the slabs to form a joint that can be easily pointed.

The depth of the dig and the necessity for a sub-base will depend on the intended use and ground conditions. If a sub-base is required the depth should be approximately 190mm minimum. This will allow for:

• 100mm compacted hardcore or crushed stone with extra care being taken to ensure any soft spots are identified, dug out and filled.
• 25mm - 40mm slab depth
• 50mm bed

If a sub-base is not required, dig to 90mm. If elevating to a higher level, then the elevation should be constructed by adding to the sub-base layer not by increasing the trickness of the bedding layer.

Driveways will always require a sub-base made up of 100mm 'MOT Type 1' hardcore so the dig will always be 190mm minimum.

Decide where the paving is to be laid and mark or peg out clearly. Dig out a little wider than the planned project width, allowing an extra 50mm - 75mm at the edges to make handling much easier. Bear in mind that any paving surfaces should be at least 150mm below a damp proof course and should have a 1:60 fall away from the building for surface drainage.

Remember to remove all weeds and other unwanted organic matter.

The mixed size crate can be utilised to give several laying patterns, an example is shown below. In this section we are outlining the principle considerations for laying natural paving. However each project will have its own individual considerations and the advice of a professional should always be sought.