Decking Installation in Newmarket - How We Build a Deck, Start to Finish

Step one: looking at the site before anything else

Every decking job starts with a proper look at the ground, the garden layout and any structures nearby. We check the slope of the ground, because a deck that is not level will drain badly and stress the frame unevenly over time. We look at what the posts or frame will bear on: solid ground, soft topsoil, made-up ground or an existing hard surface. We also check the proximity to the house - if the deck will be attached to the building, the wall construction and the damp-proof course level both affect how the ledger is fitted.

This stage also covers access. Can a cement mixer get to the footings positions, or will concrete have to be mixed by hand? Is there a boundary fence or neighbouring structure that limits how we can work? These practical details affect both the method and the price, and it is better to identify them before work starts than to discover them on day one.

Step two: design and setting out

Once we understand the site, we set out the deck on paper: overall dimensions, height, post positions, joist centres and the direction the boards will run. For a simple ground-level platform this is straightforward. For a split-level or raised deck, the structural design needs more care - post sizes, joist depths and beam sizes all increase with span and height.

Board direction affects how the frame is designed. If the boards run front-to-back, the joists run side-to-side. If you want a diagonal or herringbone pattern, the frame needs to be planned for it from the start, because you cannot lay a diagonal pattern on a frame designed for a straight lay. Getting this right on paper before cutting any timber saves waste and rework.

We also confirm at this stage whether planning permission or building regulations approval is needed. Decks above 300mm from ground level, or on listed buildings or in conservation areas, may require a formal application. In Newmarket as elsewhere, it is the homeowner's responsibility to obtain any necessary permissions, but we flag anything that looks like it needs checking.

Step three: footings

The footings are the part of a deck that most homeowners never see, and they are the part that determines whether the deck stays level and firm for its full lifespan. For a freestanding deck, we dig to below the frost line and pour concrete pad footings or set post sockets in concrete. We allow the concrete to cure before loading it with the frame above.

For a deck attached to the house, the ledger board is bolted to the wall with expanding bolts at centres specified by the load. A proprietary flashing is fitted above the ledger before the frame goes on, to throw water away from the wall rather than letting it run behind the timber. This detail is frequently skipped by less careful builders and is a common cause of water ingress and rot at the house wall.

Ground-level decks on flat ground sometimes use surface-mounted post bases on a concrete pad rather than in-ground posts. This keeps all timber above ground level and is acceptable practice when the pad is correctly sized for the load. The decision between in-ground posts and surface bases depends on the ground conditions and the height of the deck.

Step four: building the frame

With footings set, we build the subframe: posts, beams and joists. All structural timber is pressure-treated to the appropriate use class - UC4 for any timber in ground contact, UC3 for above-ground structural members. Joist centres are typically 400mm for 32mm boards and up to 450mm for thicker boards. Going wider than this to save timber is a shortcut that produces a bouncy deck.

Joist hangers are used at connections rather than skew nails, which pull out over time under repeated loading. All hangers and framing connectors are galvanised or stainless steel - not bright steel, which will rust through within a few years outdoors. Where the frame meets a house wall, there is a 10-15mm gap behind the ledger to allow drainage and prevent the frame holding water against the masonry.

We set the frame with a deliberate fall of 1-in-100 away from the house. This is small enough to be invisible to the eye but significant enough to shed standing water. A perfectly level frame, while it sounds desirable, holds puddles and accelerates the deterioration of both boards and frame.

Step five: laying the boards

Boards are laid starting from the most visible edge - usually the edge closest to the house or the seating area - and working outward. Each board is checked for straightness before fixing: even pressure-treated boards come with a slight bow, and they need to be pulled into line before the screws go in, otherwise the gaps between boards are uneven and the deck looks untidy from the start.

Boards are fixed with stainless steel decking screws, two per board per joist. Hidden fixing clips are an option for certain composite and hardwood products; they give a cleaner surface but add to installation time. Standard screws countersunk flush with the surface are the more practical choice for softwood. Pre-drilling is essential for hardwood to avoid splitting.

Board spacing of 5-6mm is standard. This allows seasonal movement (timber swells and shrinks across the grain with moisture changes) and drainage. Boards that are butted tightly together will cup and twist as they dry out.

Step six: edge details, steps and balustrades

The edges of a deck can be finished several ways: a fascia board covering the end grain of the deck boards and the joist ends, a picture frame of boards laid flat around the perimeter, or the joists left exposed with the boards overhanging. A fascia gives the cleanest finish and protects the end grain, which is the most vulnerable part of any timber section.

Steps need to be built to the same standard as the deck itself: solid stringers, concrete footings under the bottom post if the steps are freestanding, and treads fixed firmly. A step that moves underfoot is both annoying and a trip hazard.

Balustrades are required by building regulations on decks above 600mm from ground level. The standard requires a minimum height of 1,100mm from the deck surface and infill that prevents a 100mm sphere from passing through. We design balustrades to meet these requirements and to match the style of the deck - horizontal rails, vertical balusters or glass panels, depending on what suits the space and the budget.

Step seven: finishing and treating

New softwood decking should be left to weather for six to eight weeks before the first application of oil or end-grain sealant. This allows the wood to stabilise and open up to accept the finish properly. Treating too soon means the finish sits on the surface and peels rather than penetrating the grain. End grain on any cut sections should be sealed on the day of cutting to prevent moisture uptake at the most vulnerable point.

Step eight: clean-up and handover

When the deck is complete, we remove all off-cuts, packaging and concrete bags, and leave the site clean. If we have disturbed turf or planted areas to get to footing positions, we reinstate as far as possible. The handover is a walkthrough of the finished structure - we show you where the fall runs, how the fixings are arranged, and what the maintenance schedule looks like for the material used.

If you are planning a deck in Newmarket and want to understand what the job involves for your specific garden, call us and we will come and take a look before anything is committed.