Laying slabs on sand with mortar

Preparation is the secret of sound paving-expect it to take at least as long as actually laying the slabs. Do not lay paving slabs straight onto the soil,because rain water will get under them ,making the soil soft and muddy.the slabs will then sink in ,wearing depressions in the soil and causing the slabs to rock.the paving soon becomes uneven and can be dangerous if the slabs tip up.To prevent this happening,prepare a proper ‘base’ before you lay any slabs.It need not be very deep,as a patio or path will not have to carry much weight.Start by leveling  and consolidating the ground.You may need to excavate a few inches of soil for the base,leaving only the paving visible above ground.Alongside  a house wall ,leave a gap of 6 in(15 cm) between the surface of the finished paving and the dampproof course in the wall.If laying a patio, whether it be adjacent to the house or free-standing,leave the ground sloping very slightly so the water runs off it.A slope of 1in(2.5 cm) in 4ft(1.2m)is all that is needed.

Slabs on sand with dry mortar

There are some situations where fixed paving slabs are neither necessary nor desirable.If you think you may want to alter the patio layout later, perhaps taking up some slabs to make a sunken bed or pond ,then it will be easier if you only have to lift the slabs.Slabs in such an area can simply rest in place while those around them are mortared down permanently.If you use very large heavy slabs,cement may not be necessary at all ,especially if the patio surface will not take much weight.Even if they are not cemented down,you can still fill in the cracks between the slabs with mortar to stop weeds growing.Later on you can remove the slabs with a crowbar after chipping the mortar loose;clean up the edges before reusing the slabs.Alternatively,leave the cracks between slabs open ,perhaps filled with gravel ,and sow rock plants between them.To prepare the site for laying slabs,proceed as described for laying paving slabs ,using crushed rubble or ballast covered by building sand,raked firm and leveled.Leave a 6in(15 cm)gap between the dampproof course in the house wall and the planned upper surface of the patio,and allow a very slight slope away from the house to deflect water during heavy rain.

 

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