By Karl Harrison — garden designer and decking expert
The brief
The clients wanted a quietly sophisticated terrace connected to the existing terrace, with space for dining, occasional parties, and everyday calm. The deck needed to read as an extension of the interior: crisp lines, soft colour, minimal maintenance, and reliable slip performance in London’s climate.
Concept: proportion and movement
We set out the plan from a primary datum at the threshold of the terrace, then composed the deck as three zones—an arrival strip, a central living field, and a perimeter frame that resolves edges, lighting and planting. Every board run aligns to architectural features; transitions are purposeful; nothing is accidental. Sightlines out to the garden are clean and unobstructed.
Structure: EC5 at the core
A beautiful deck fails without a proper skeleton. The frame is engineered to Eurocode 5 (EN 1995-1-1) principles:
- Load model: Domestic use at 1.5 kN/m² UDL plus point load checks.
- Joist centres: Controlled to ≤400 mm to limit deflection and maintain fastener engagement; perimeter stiffeners reduce edge bounce.
- Service class & durability: External, ventilated build-up designed as Service Class 3 with moisture management, separation from ground, and corrosion-resistant fixings.
- Deflection and vibration: Span and depth chosen to keep instantaneous deflection ≤ span/300 (felt as solid underfoot).
- Drainage & falls: A gentle fall away from level—imperceptible to the eye, essential for longevity.
- Interfaces: Threshold details maintain clearances to the steel wraparound of the terrace; no fixings into the sill; continuous airflow behind cladding returns.
“We used accurate measurements across the field, verified with laser as we built. Structure first, always”.
Accuracy: the craft you don’t see
Design lives or dies on execution. We templated every junction, pre-drilled pilot locations, and staged fixings to keep shadow gaps consistent end-to-end. Services (lighting and future power) run in protected routes with accessible panels that disappear into the layout. Corners mitre true; edges track parallel; nothing drifts as the eye moves across the surface.
Material choice: Deckorators Excursion “Oslo”
While this story is about design and build quality, material matters. Deckorators® Excursion is a mineral-based board with minimal thermal expansion and very low moisture movement, which means tight, consistent joints and excellent dimensional stability through British seasons. The “Oslo” colour is a refined, architectural grey with a matte, high-end finish—calm beside brick and render, elevated by planting greens. The board’s traction profile supports confident footing without looking industrial, and its low-maintenance surface fits busy London living.
(Note: boards were installed to manufacturer guidance for gapping, fasteners and perimeter ventilation to preserve warranty and performance.)
About Karl: design, detail, delivery
Karl is a designer who builds. For over two decades he’s planned and delivered high-end outdoor spaces in the UK, with a particular focus on decking as architecture—structure, detailing and longevity before everything else. His approach blends garden design (sight-lines, movement, planting) with construction logic (load paths, moisture, tolerances). This London project—finished in Deckorators® Excursion “Oslo”—shows how that mindset turns a simple terrace into a refined, durable living space.
Detailing: quiet sophistication
- Framed field: A subtle border frames the main area and allows clean edge terminations without exposed cuts.
- Stairs & edges: Closed risers, discreet nosing, and low-glare step lighting guide movement after dark.
- Furniture zones: Hidden anchor points stop dining sets from drifting; felt pads keep everything gentle on the surface.
- Planting: Evergreen structure with seasonal accents softens the geometry and screens neighbouring views.
Installation quality: the difference you feel
Our installer team works to a checklist culture: fixings torque-checked, ventilation verified, drainage paths cleared, and a handover pack with care notes, as-built drawings, and warranty records. Clients experience that as a deck that feels solid on day one—and still feels solid years later.
Living with it
The deck is designed for real life: quick washdowns, no sanding, no staining. Shadow gaps stay true, fascias sit flat, and the colour reads beautifully in every weather. Morning coffee feels composed; evening meals feel special.
Why choose Karl for your London deck
- Design-led: Garden design and structural thinking in one place.
- Code-aware: EC5 principles applied from layout to fixings.
- Detail-driven: Millimetre-level accuracy and clean, durable detailing.
- Proven delivery: Premium projects across London and the South East.
- Supported by Manufacturers: His work is backed by warranty
Project snapshot
- Location: London
- Designer: Karl Harrison
- Decking: Deckorators® Excursion – Oslo
- Engineering approach: Eurocode 5 principles, Service Class 3, ≤400 mm centres
- Supports: Adjustable pedestals for precise falls and ventilation
- Lighting: Warm, low-glare step and perimeter accents
- Outcome: A calm, architectural terrace—stable, accurate and elegant
FAQs
Why EC5 for a residential deck?
Because it gives a shared language for span, deflection and durability. It turns “rule of thumb” into measurable performance. It is also the minimum standard that decks in the UK must be constructed too.
Can mineral-based boards be used on roof terraces?
Yes—when paired with the right build-up, drainage and ventilation. Always follow manufacturer guidance and obtain approvals.
How long does a deck like this take?
Design and procurement are typically 2 weeks; installation 5–10 days depending on ground conditions and access.
Let’s design yours
Ready to bring design, structure and style together on your project?
Email: hello@deckingbykarl.com • Phone: 07581 193034
