Does composite decking get hot in summer?

Yes — darker colours can reach 60–70°C in direct London summer sun; uncomfortable on bare feet for 4–6 hours mid-day. Lighter colours (silver-grey, bleached oak, light walnut) stay 10–18°C cooler. Shade strategy: pergola, mature trees, parasol — essential for south-facing decks. Hardwood and softwood marginally cooler in sun than composite but all dark deck surfaces heat. Cool composites (Trex Transcend in lighter shades) specifically engineered with reflective caps to reduce heat absorption — slight cost premium.

Can I lay composite decking over an existing patio?

Yes — pedestal or sleeper system over existing concrete or paving. Sleeper system: 47×100mm pressure-treated joists laid on existing slab, levelled with shims, boards screwed to joists. Build-up 120–150mm. Pedestal system: adjustable pedestals on existing surface, joists on pedestals, boards on joists. Build-up 80–200mm depending on pedestal height. Pedestals ideal where existing surface uneven; sleepers cheaper. Cost adder £25–£55/m² over standard install due to elevation framing.

How do I clean composite decking?

Annual jet wash (low pressure 1000 psi maximum — high pressure damages cap) in spring. Stains: warm soapy water and stiff brush. Algae: composite-safe cleaner (Wet & Forget, Net-Trol) — never bleach. Mould between boards: brush + cleaner. Never sand composite (destroys cap layer). Annual servicing: tighten fascia screws, check ventilation under deck, replace damaged boards (individual boards replaceable). 25-year warranty typical assumes minimal cleaning.

Is composite decking eco-friendly?

Mixed. Composites are 60–95% recycled content (Trex 95% recycled wood + plastic; Millboard 30% mineral content); long lifespan reduces replacement cycle vs softwood. Manufacturing carbon footprint higher per kg than timber but offset by lifespan. End-of-life: composite is not biodegradable; recycling routes limited (Trex recycle programme available US, limited UK). FSC-certified hardwood from sustainable forestry is most eco-credentialed if responsibly sourced. For pure embodied carbon, sustainable hardwood wins; for waste reduction over time, composite wins.

Composite Decking Cost London 2026 | Builderr

How Much Does Composite Decking Cost in London?

Composite decking in London costs £180–£280/m² supplied and installed. Boards £85–£140/m² for capped composite (Trex Transcend, Millboard Enhanced Grain); substructure £35–£65/m²; install labour £55–£85/m². Lifespan 15–25 years vs softwood 5–8 years. No staining, no rotting, fire-resistant grades available. Width 140mm boards typical. Adjustable pedestals for hidden services £85–£140/m² adder.

Composite decking products and pricing

Capped composite (wood-plastic composite with PVC or polyethylene cap layer for stain resistance and colourfastness): Trex Transcend, Trex Enhance, Millboard Enhanced Grain, Ecodek Heritage, Composite Prime HD. Supply £75–£140/m² depending on tier. Premium PVC composites (Millboard) are highest-end — mould-cast surface, exceptional colour authenticity, 30-year warranty. Standard wood-plastic composites (Trex, Composite Prime) — extruded, regular wood-grain texture, 25-year warranty. Board widths 140–145mm standard; 180mm wide premium boards add £25–£45/m². Board lengths 3.6–6m typical. Colour options: warm browns (espresso, walnut), greys (charcoal, dove), bleached oak — premium ranges 8–12 colours. Hidden fixings: stainless steel clip system at every joist — material cost £8–£18/m². Fascia and trim £25–£55 linear metre. Step nosing £35–£65 linear metre.

Substructure — the often-skipped cost

Decking substructure is 35–45% of total cost and frequently underspecified. Best practice: pressure-treated softwood joists 47×100mm or 47×150mm at 400mm centres (composite typically requires 400mm — verify manufacturer spec); galvanised joist hangers or 100×100mm concrete supports at 1.2–1.8m centres; double-joists at board ends for fixing support. Composite materials cannot bridge wide spans like hardwood — joist spacing critical to avoid creep and bounce. Cost £35–£65/m² for substructure (timber + fixings + concrete pads). Alternative: aluminium joist system (Eurodek, Buzon pedestals) £45–£95/m² — fully maintenance-free, ideal for ground-level decks or roof terraces. Pedestal systems for adjustable-height decking over roof membranes or services: £85–£140/m² — essential where deck must lift for membrane access. Damp-proof the substructure: 600mm air gap below boards ideal; geotextile membrane below if ground-level prevents weed growth.

Composite vs hardwood vs softwood

Softwood deck (treated pine, larch): £85–£140/m² installed. Cheap upfront but lifespan only 5–8 years before significant decay; requires annual oiling/staining £8–£15/m²/year ongoing; surface roughens, splinters develop, fixings work loose. Total 15-year cost (replacement + maintenance): £180–£280/m². Hardwood deck (iroko, balau, ipe): £220–£340/m² installed. Excellent lifespan 25–40 years; requires annual oiling for colour preservation (£8–£15/m²/year) or accept silver-grey weathering. Beautiful natural appearance; tropical species sourcing increasingly restricted under FLEGT — verify FSC certification. Composite deck: £180–£280/m² installed. 15–25 year lifespan; zero ongoing maintenance (jet wash only); colour stable. No splintering, no fixing creep. Total 15-year cost: £180–£280/m² (same as install — no ongoing). Verdict: composite wins on lifecycle cost and convenience; hardwood wins on aesthetics (premium feel); softwood loses on lifecycle (cheap upfront but expensive over time).

Install, layout and integration

Layout: longest deck board direction perpendicular to predominant view (e.g. boards running away from house emphasising depth); diagonal layouts add £15–£35/m² in cuts and wastage; herringbone or chevron layouts are premium designs adding £45–£85/m² and 30% material wastage. Threshold to house: minimum 150mm below internal floor level (DPC requirement); flush threshold requires elevated DPC or coordinated French drain along house edge. Step detail: 175mm rise maximum; nosing strips for safety; LED step lights £25–£75 each excellent integration. Lighting: low-voltage LED deck lights £25–£45 each; transformer in concealed location. Drainage: gaps between boards (5–8mm) allow rain through; ground below must drain — gravel + geotextile fabric £8–£18/m² or sloped concrete to soakaway. Integration with garden: deck typically defines 30–60% of garden hard surface — design proportions carefully to avoid 'deck island' feel. Mix with planting borders, pergola, or terraced levels to create rooms.