Mortar Bedding

Slabs can be 'spot-bedded' with a small mound of mortar at each corner and one in the middle; whilst this is easier to adjust and correct than other types of bedding it is also weaker.
A full mortar bed provides the strongest support but can make it difficult to get the slabs true and level.
Box and Cross bedding is a good compromise; providing good support while allowing the mortar to squeeze sideways during levelling.

Basic laying steps

• With a trowel place strips of mortar so that they form a rectangle slightly smaller than the slab dimensions, enclosing a cross strip. The cross strips can be omitted for small square slabs, but large rectangular slabs may need to be double-crossed. The strips should be 30-50mm high.
• Position the first slab on the mortar bed and temp it level with a wooden or rubber mallet or a length of timber. It should not rock in any direction. Check for accuracy in both directions.
• Repeat with successive slabs. Joint width will depend on the dimensions of the units, but will generally be 10-12.5mm.
• Check alignment and level against adjoining slabs with a straight edge spanning two or more flags.