Jonathan White, R&D executive at Gleeds, looks at landscaping and drainage costs
Landscaping has four main elements: plants, terrain, manmade structures and weather.
It is important that the construction programme for landscaping works is tied in with the best times for planting and allows enough time for ground preparation.
Planting should generally be carried out in September or October. Deciduous trees and shrubs prefer October to March while conifers and evergreens can be planted in April or May. Any time is fine for container grown plants so long as the ground and weather conditions are favourable. Planting should be avoided in frosty, cold, windy, hot, sunny or drying conditions. Cloud and drizzle are the ideal weather.
Sustainable Urban Drainage Systems (SUDS) replicate natural drainage and reduce the environmental impact from surface water run-off. Local authorities increasingly require developments to include SUDS to reduce pollution and flooding risk, improve the environment and potentially reduce costs.
To shed water and leave a dry surface to eliminate ponding and icing, footways tend to require differing minimum falls. These usually occur in either cross-fall or camber. Paving slabs require the shallowest cross-fall, 1 in 70, while gravel needs an incline of 1 in 30. To be DDA compliant paved areas should have a minimum cross-fall of 1 in 60; for footpaths the range should be between 1 in 40 and 1 in 30.
Care should be taken when disposing material off site, especially topsoil and subsoil. In 2012, HMRC published a general guide to landfill tax identifying £64 per tonne for fine grade material. Such material is derived from the recycling of construction and demolition waste along with topsoil, subsoil and rubble used for landfill cover. Previously, recycled waste from construction and demolition (inert materials) had attracted a reduced land fill rate of just £2.50 per tonne.