Timber & Composite DeckingBuilt Level, Square And SafeAcross Bucks & Surrey
Softwood, hardwood and composite decking built on properly footed sub-frames, level underfoot, square in the corners, and covered by a 12-month workmanship guarantee.
About Our Decking Service
What it is
Decking is a raised or ground-level timber or composite platform built on a joisted sub-frame supported by concrete pad footings or ground screws. Done properly, it flexes evenly under load, stays square through the seasons, and provides a smooth, safe outdoor floor.
Who it's for
Homeowners extending outdoor living space, families wanting a garden entertaining area, and property owners across Amersham, Beaconsfield, Chesham, the Chalfonts, Great Missenden, Hazlemere and Farnham replacing tired old decks with something built to modern spec.
When you need it
You need new decking when an existing deck feels spongy, tilts, has rotten boards or a wobbly balustrade, or when you're creating a new outdoor entertaining zone from scratch. Composite is the natural upgrade when a softwood deck reaches end of life.
Why professional installation matters
Decking fails at the sub-frame long before the boards. Cheap installs use undersized joists, no bearer supports, and pad stones sat on turf. We build sub-frames from C24 pressure-treated timber on concrete pad footings, level to laser accuracy, and space boards for proper drainage.
What Happens If You Leave It
Small problems don't stay small. Here's what we see when homeowners delay, and the corner-cutting mistakes that make it worse.
Spongy, sagging deck boards
Joists spaced too far apart (over 400mm centres on softwood, over 300mm on composite) sag between supports. The deck feels alive underfoot within 3–5 years.
Rotten bearers and frame collapse
Sub-frames sat on soil or bark chip rot from below within 5 years. Once the frame goes, the whole deck goes with it, often without warning.
Slippery, splintery boards
Deck boards without grooves, ribbing or a proper aftercare seal turn slick in winter and splinter in summer. Composite avoids both, but only the higher-density brands do it well.
Our Decking Process
A clear, in-person system from first visit to final handover, no surprises, no scope creep.
- 1
In-person site survey
We take levels, check for existing footings, discuss timber vs composite, and sketch layout including steps, balustrades and lighting.
- 2
Fixed written quote, same day
Itemised, footings, sub-frame, decking, fascia, balustrades, steps, disposal of old deck. All fixed in writing.
- 3
Site prep & footings
Existing deck stripped, ground cleared, concrete pad footings poured to correct depth and spacing (or ground screws installed for suspended decks).
- 4
Sub-frame construction
C24 pressure-treated joists at correct centres (400mm timber, 300mm composite), bearers on pad stones, whole frame levelled with a laser and squared.
- 5
Boards, fascia & handover
Deck boards fixed with correct spacing, hidden or countersunk fixings, fascia and step risers installed. Full walk-round, 12-month workmanship guarantee starts.
Why Homeowners Choose Hi Design
Level, square and safe underfoot
Laser-levelled sub-frame means no dips, no rocking, no trip hazards, for the life of the deck.
Correct spacing for drainage
Boards spaced 5–8mm apart so water sheds through, timber can dry, and rot doesn't get a foothold.
Long-life composite option
Composite decking (Trex, Millboard, Composite Prime) carries 25-year warranties and needs zero staining or sealing.
Recent Decking Projects
A selection of finished decking work across Buckinghamshire and Surrey.
Decking: The Detail
Timber vs composite, the honest comparison
Softwood (Tanalised pine, redwood): cheapest option, 8–12 year life, needs annual clean and re-oil, natural look. Hardwood (Balau, Ipé, Yellow Balau): 20+ year life, premium look and feel, higher cost and needs specialist fixings. Composite (Trex Enhance Basics, Composite Prime HD, Millboard): 25-year warranty, no maintenance beyond a wash-down, higher upfront cost, doesn't fade or splinter. We install all three, the right choice depends on budget and how much aftercare you want to do.
Sub-frame spec, joists, bearers, footings
Domestic decks use C24 grade pressure-treated 145x45mm joists at 400mm centres (timber decking) or 300mm centres (composite). Bearers 150x75mm minimum, sat on 300x300x100mm concrete pad footings dug to firm subsoil. Ground clearance minimum 150mm to allow air flow beneath. Steel joist hangers and coach screws, never nailed only.
Boards, fixings and spacing
Softwood/hardwood boards fixed with A2 stainless steel screws (pre-drilled on hardwood), spaced 5–6mm apart for drainage and expansion. Composite boards use hidden clip systems (Cortex, Camo) for a fastener-free surface, spaced 6–8mm, critical for expansion in summer heat. All boards laid with grooves facing down for grip in wet weather.
Steps, balustrades and building regs
Decks over 600mm above ground need a balustrade (Part K building regs), 1100mm high on domestic decks, with baluster gaps under 100mm. Steps built with 180mm rise, 250mm going, and non-slip nosings. Decks attached to the house are notched onto a wall-plate flashed against the DPC, we never bolt straight through render.
Residential vs commercial and roof decks
Residential garden decks: standard timber sub-frame on pad footings. Commercial (pubs, restaurants, holiday parks): heavier joists, non-slip Class R11 boards, and Building Control-compliant balustrading. Roof decks and balconies: aluminium sub-frame on rubber pedestals with a protective membrane layer over the roof waterproofing.
Decking, Common Questions
Build A Deck That Stays Level For A Decade
Free in-person survey. Fixed written quote same day. 12-month workmanship guarantee.
Free site visit · Fixed written quote same day · 0% deposit · £10m insured