What to Expect from a Trex Composite Decking Installation

Booking a composite deck is easy. Knowing what actually happens between booking it and standing on it is another matter. If you’re weighing up a Trex composite decking installation in South Wales, here’s what the process really looks like, from the first site visit through to the final board.

Before Installation Day: Design and Groundwork Prep

Nothing gets built until the groundwork is right. Before any boards arrive, we visit your garden, measure up properly, and talk through what you actually want the space to do. Steps, seating, lighting, borders, it all gets planned before a single joist goes down.

If you’d like, Ellis can produce a detailed 3D design render before we start (an optional extra, priced per project), so you can see the finished layout and colour before we commit to anything. It’s a simple way to catch changes early instead of after the boards are down. If you’re still choosing, our guide to Trex decking ranges breaks down Enhance, Transcend and Signature.

This is also when we check the ground itself. Composite decking only performs as well as what’s underneath it, so we look at levels, drainage, and what the existing surface is doing before we plan the subframe.

Day One of a Trex Installation: Site Prep and the Subframe

Installation starts with clearing and levelling the site. Old decking, paving, or overgrown ground all get sorted before we mark out the deck itself.

The subframe comes next, and this is where a lot of decks go wrong if it’s rushed. We build ours to Trex’s UK specification, using treated joists spaced closely enough to support the boards properly and stop them flexing underfoot. It’s the part of the job nobody sees once it’s finished, which is exactly why we don’t cut corners on it.

We’re a TrexPro® Gold installer, one of the higher tiers of Trex’s installer programme, and the subframe is where that training actually shows. Get it wrong and even good boards will move, dip, or fail early. Our guide to what a TrexPro Gold installer is explains why that matters.

Board Acclimatisation: Why We Wait Before Fixing Trex Boards

Composite boards need time to settle to the temperature and humidity of your garden before we fix them down. Skip this step and you risk boards expanding or contracting after installation, which shows up as gaps or pressure at the joints later.

It’s a step some installers skip to save time. We don’t, because it’s the difference between a deck that stays flat for years and one that starts showing problems within a season.

Installing the Trex Boards: What Actually Happens

With the subframe ready and boards acclimatised, we start fixing from a fixed edge, usually the house wall, and work outward in straight, checked rows. Every board gets checked for alignment as we go rather than at the end, because small drifts compound fast if you don’t catch them early.

Expansion gaps are built in throughout, sized to the conditions on the day, so the deck has room to move with the seasons without buckling or gapping. We double-check spacing every few boards rather than trusting it to hold on its own.

The Finishing Touches on a Composite Deck

Once the main deck is down, we add whatever’s part of your design. That might be step edges, fascia boards to hide the subframe, railings, borders or built-in lighting. This is also where any inlays or feature details go in, since they’re easier to get right once the main run is finished and true.

We photograph progress throughout the build, so you’re never left wondering what’s happening between visits.

Ready to plan your deck? Call Ellis on 07971 750900 or request a free estimate.

How Long Does a Trex Composite Decking Installation Take?

A straightforward garden deck usually takes from a few days to around a week, from site clearance to finished boards. Larger builds, or ones with steps, railings, multiple levels or a lot of detailing, typically take two to four weeks.

We’ll always give you a realistic timeline at the design stage rather than a generic number, because a small platform deck and a multi-level deck with built-in seating are very different jobs. See our guide to decking on sloped gardens for how multi-level builds differ.

What Makes an Ellis Decks Installation Different

Ellis has been installing composite decking for over 12 years and is a TrexPro Gold installer, which means Trex itself has vetted the standard of work. That matters because a Trex board is only as good as the person fitting it.

Customers notice the difference in the groundwork specifically. As Nick Codrington put it after his install: “Don’t make the mistake of going with the cheapest option, I found out the hard way. The installation process was smooth and Ellis couldn’t have been more professional or helpful, with great attention to detail ensuring a flawless finish.”

David Hathaway had a similar experience: “Ellis was very professional from start to finish. He came up with very good ideas for the design. Extremely pleased with the finished deck and railing system.” You can read more reviews like these on our reviews page.

If budget is part of the decision, our cost guide covers real numbers for South Wales, and our composite decking page covers everything from cost to lifespan. For the manufacturer’s own technical detail, Trex’s installation guides are a useful reference, though we’d always recommend a TrexPro installer over a DIY build for anything beyond a small platform.

We install across South Wales and the borders. Call 07971 750900 or get in touch to book your free design visit.