Decking Cost Calculator UK (Composite & Timber)
Calculate UK decking project cost by area and material type. Includes boards, frame, fixings, foundations, and labour for typical residential decks.
UK Decking Cost Guide 2024
Material Comparison
Pressure-treated softwood: cheapest. £25-40/m² for boards. Lasts 10-15 years with regular maintenance (annual oiling). Affordable starter material. Splinters, warps over time. Stained colour fades. Hardwood (iroko, cumaru, garapa, ipe): £70-120/m². Lasts 20-30+ years. Beautiful natural finish. Dense, doesn't splinter as readily as softwood. Sustainably-sourced increasingly available (FSC certified). Composite (basic — wood-plastic composite, WPC): £60-100/m². 15-20 year lifespan. Low maintenance
Installation Realities
Sub-frame is half the project. Treated softwood joists at 400mm centres. Posts/Adjustable footings every 1.5-2m. Joist hangers, galvanised brackets. Galvanised or stainless steel fixings (rust visible on cheap fixings within a season). Cost: £20-40/m² for materials alone. Foundations: ground level: gravel base 100mm + permeable membrane. Low decks: concrete pads or screw piles. Raised decks: deeper concrete footings to frost depth (450mm+). Elevated decks: full structural design needed. Labour:
Maintenance Requirements
Pressure-treated softwood: clean annually (jet wash or brush + decking cleaner). Oil/stain every 1-2 years (£20-40 per deck). Replacement boards every 5-10 years for high-traffic spots. Hardwood: oil with hardwood oil every 1-2 years to maintain colour. If left to grey naturally: clean annually only. Either approach works — depends on aesthetic preference. Composite (WPC): annual clean with deck cleaner. No oiling, sealing, or painting needed. May stain from oily food spills. Recyclable but only
Planning & Compliance
Planning permission: usually NOT required for ground-level/low decking under 30cm high covering less than 50% of garden. Required if: deck height over 30cm — many councils require planning even at low heights now. Conservation areas: stricter. Listed buildings: virtually always need consent. Building regulations: required if deck height enables a 1.5m+ drop (railings needed, structural sign-off required). Building Regs Part K: 1.1m minimum balustrade height. 100mm maximum gap between spindles. C
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