External works or civil engineering design for external areas can be complex and sensitive. Strength, durability, cost and future-proofing all need to be considered. The requirements at different sites are rarely the same.
The Royal Institute of Chartered Surveyors’ recently published New Rules of Measurement Part 3 (NRM3) gives guidance on external works, categorised as: site preparation works; roads, paths, pavings and surfacings; soft landscaping, planting and irrigation systems; fencing, railings and walls; external fixtures; external drainage; external services; and minor building works and ancillary buildings.
Hardscape, or hard landscape, consists of the motionless non-organic elements of landscaping. They are unchanging, although they may be movable and adaptable. Hardscape might include walkways, walls, outdoor ‘rooms’ and performance areas, gazebos, fences and so on.
Softscape or soft landscape includes all types of plant life, from flowers and trees to shrubs and groundcover. It naturally changes over time, driven by the climate, time of year and other conditions. Consideration should be given to the amount of maintenance that these elements will require to stay in good order.
The rates below are a guide to landscape and drainage costs as at 2019 Q1. No allowance is made for sundry or related preliminaries. VAT is excluded.
Range £/100m2
Housing developments
Housing cost models meeting minimum planning requirements or to maximise sales potential at economic cost. Soft landscaped space only space; planting: turf ratios as shown; planting sizes and densities as indicated; one tree of 18cm-20cm girth at one tree per 100m2 overall external area; mulch and watering after planting
Landscaped area, turf and trees only ; imported topsoil to turf areas at 50mm thick £1390-£1590
Landscaped area 70:30 turf to planted area with imported topsoil to turf areas at 50mm thick £2440-£2790
Landscaped area 50:50 turf to planted area; imported topsoil to turf areas at 50mm thick £2730-£3120
Generally areas of more dense landscape incorporating relaxation areas and larger planting schemes; planting is generally more mature at implementation with larger trees; planting schemes often incorporate larger swathes of groundcovers to give graded views over landscaped areas; planting density and sizes are generally of higher standard than housing; soft landscaped space only space; planting : turf ratios as shown; planting sizes and densities as indicated; one tree of 25-30cm girth at one tree per 100m² overall external area; mulch and watering after planting
Landscaped area, turf and trees only; imported topsoil to turf areas at 50mm thick £1650-£1890
Landscaped area 70:30 turf to planted area with imported topsoil to turf areas at 50mm thick £2730-£3120
Landscaped area 50:50 turf to planted area; imported topsoil to turf areas at 50mm thick. £3050-£3480
Civic environments and streetscape
Civic and public areas in the current climate encompass higher quality surfaces for public access. Planting is generally larger. There is a need for furniture and lighting
Civic town centre area of paved open space; model area 500 m2
General open area; one 30-35cm trees with root cell planting system every 400m²; metal tree grid; one bench per 200 m² and one bin per 500 m²; granite kerb surround
Heritage concrete slab paved £17,330-£19,800
Granite paved £21,000-£24,000
Granite paved with stepped terraces. Three steps of 10m long each in an area of 500m2 £24,680-£28,200
Living wall; Design and installation of planted modules with automatic irrigation systems
Fabric based systems; indicative area rates as shown
Wall up to 20m²/50m²/100m²/150m² £660-£755 / £515-£590 / £495-£565 / £480-£545
Surfaced areas
Parking; block paviors 80 mm thick £80-£100
Pedestrian areas, 100 mm thick concrete £60-£75
Modular grass concrete paving ,100 mm thick £77-£97
Resin bonded 1mm-3mm golden pea aggregate pathways £77-£96
Parking; macadam base and wearing course (bay 2.5m by 5.5m) £900-£1200 per bay
Drainage
Access chambers
Excavate inspection chamber; concrete base; half section pipework and benching
Engineering brick inspection chamber 600x400x1000mm deep nr £460-£560
Polypropylene inspection chamber, mini access chamber 600mm deep nr £340-£410
475mm dia x 900mm deep; ductile iron cover with screw down lid nr £600-£675
Drainage pipe, excavate and lay:
100 mm diameter upvc pipes over 1.0m deep £51-£65
150 mm diameter clay pipes over 1.5m deep £90-£110
300 mm diameter concrete pipes over 2.5m deep £170-£210
150 mm diameter cast iron pipes over 1.5m deep £190-£240
Street furniture
Road signs; reflected traffic signs 0.25m² area on steel post nr £130-£175
Road signs; internally illuminated traffic signs; dependent on area nr £210-£280
Lighting to pedestrian areas on estate roads; 4m-6m columns with up to 70W lamps nr £260-£325
Lighting to main roads; 12m-15m columns with 400W high pressure sodium lighting nr £700-£950
Benches; hardwood and precast concrete £1200-£1800
Litter bins; bolted to ground
precast concrete/hardwood slatted nr £200-245 / £200-245
cast iron/large aluminium nr £410-£490 / nr £610-£740
Street planters: Supply and locate in position precast concrete planters; fill with topsoil placed over 50 mm shingle and drainage mat; plant with assorted 5 litre and 3 litre shrubs to provide instant effect; 700mm dia x 470mm high;
white exposed aggregate finish each £1000-£1500