Levels
One of the very first jobs on site once you are ready to start construction works, especially regarding paving, is to establish all levels across the project, not simply the area you are expecting to be working on at any particular stage. The primary reason for ensuring that site levels work effectively, is because they are all conjoined. Quite apart from constructional levels for various raised beds and features, the constant theme across the site is to ensure water can move from one part of the garden to the other, starting with the highest point first, then extrapolating different height and level pegs whilst having due regard to the last fixed level point to the next. (See Falls on Paving Projects.)
It is usual for all plans to show a Datum Point, which is Ground Zero (often a door sill, or other fixed point, one that will not alter at any point during construction). All other points annotated on a drawing or plan will show plus or minus signs (+ -) indicating the direction of intended water travel. On sites where no fixed datum point can be identified, install your own datum using a firm peg sited away from areas that machinery may need to traverse.
Even when a project element is required to be level, e.g. a raised pool, or seating area, the ‘ground level’ point must show a cross fall to a water outfall (drain, soakaway, culvert, ditch etc). Any interruption in the ground level fixed points may result in ponding or puddles laying within the scheme, which will be very difficult to eradicate once the project is complete.
A landscape scheme should be treated in exactly the same manner as a building site – which in fact, is what it is. Care and attention to levels is crucial, as any errors can become very costly.
It is another reason for working under a strictly professional system, so that if a customer asks for additional features to be included, they may not be possible without major disruption and inordinate costs (see Variation Orders) if they interrupt the cross-site rainwater disposal plans.
Areas of porcelain paving should be laid with a fall of 1:60 to allow for water run-off from the paving to cope with surface tension, whilst most other paving is laid to falls of 1:60, which includes sandstones, granite, blocks, bricks etc.
