Smart home retrofit in London (2026): what a builder actually wires in
What 'smart home' really means in a London renovation, the one timing rule that saves thousands, wired vs wireless honestly, and the system costs from entry to full KNX.
A smart-home retrofit in London is mostly a timing decision, not a gadget one: the single rule that saves the most money is to wire it in at first fix, while the walls are open, because running cable retrospectively costs several times more. "Smart home" in a renovation means proper, integrated control of lighting, heating, audio-video and security — not a smart speaker on a shelf — and the cost runs from a few hundred pounds a room for entry-level wireless lighting up to £15,000–£60,000 for a fully wired whole-house system. This guide explains what's worth wiring and when, the honest wired-versus-wireless trade-off, the system tiers and their costs, and how a builder fits all of it into the programme.
What "smart home" means in a renovation
Forget the voice-assistant marketing — in a renovation context, a smart home is about a handful of building systems being controllable, schedulable and able to work together. The core ones are lighting control (scenes, dimming, automation), heating control (zoning and scheduling), audio-video (multi-room sound, integrated screens), and security (alarms, cameras, access, door entry). The value isn't novelty; it's a house that's comfortable, efficient and simple to run — lights and heating that respond to time and occupancy, one app or keypad instead of a drawer of remotes. The decisions that matter are made during the build, not bought afterward off a shelf.
The one rule: wire it at first fix
This is the point that saves the most money, so it leads. Anything that wants a cable — lighting circuits set up for control, data points, speaker runs, sensor and keypad locations — should go in at first fix, while the walls and floors are open. Pulling that cable later, through finished plaster and under laid floors, costs in the order of three to five times more and makes a mess of the finishes you just paid for. The practical move on any renovation, even if you're not installing a full system on day one, is to run data cabling (Cat6) to every room and to first-fix the wiring for the control you might want — so the house is ready, and the expensive, disruptive part is already done. Future-proofing a renovation is cheap; retrofitting a finished house is not.
Wired vs wireless — the honest trade-off
Both have a place, and the right answer depends on how far you're going. Wireless systems (lighting and heating controls that talk over radio) are retrofit-friendly, need no rewire, and suit a lighter touch or a home you can't open up — but they depend on signal and batteries, and they scale less gracefully across a whole house. Wired systems run on a dedicated cable backbone, which is more robust, more responsive, and the standard for a serious whole-house install — but the cabling has to go in during the build, which is exactly why the first-fix timing rule matters. A common sensible hybrid: wire the backbone for the rooms and functions you're sure about, and use wireless for the lighter, changeable extras.
The system tiers and what they cost
A rough map from entry to top, with London figures:
- Entry wireless lighting: around £200–£500 per room for app-and-scene control with no rewire — a light-touch start.
- Smart heating, retrofit: £150–£400 for a multi-zone setup that needs no rewire — one of the best value-for-comfort upgrades.
- Mid-market wired (for example a Loxone system): a typical four-bed installation runs about £12,000–£25,000, covering lighting, heating, blinds and more on a wired bus.
- Premium wired (Lutron-class lighting and control): £15,000–£60,000 across a whole house, depending on scope and finish.
- KNX, the open wired-bus standard used on high-end builds: KNX-partner integrators commonly charge £8,000–£40,000 and up, with the openness that lets different manufacturers' kit work together.
These are system and integrator costs; the cabling labour during the build is separate and is where your builder's first-fix work comes in.
How a builder coordinates it
A smart system only works if the wiring, the trades and the integrator are sequenced together, and that coordination is the builder's job. In practice that means agreeing the cable plan with the automation specialist before first fix, running the data and control cabling to the right places at the right time, leaving the correct back-boxes and routes for keypads, sensors and screens, and bringing the integrator in to terminate and commission once the shell is closed up. The trade body for AV and automation installers is worth knowing — using an established member rather than a generalist is the difference between a system that works and one that frustrates. PrimeCraft Surface Solutions plans the cabling into the first-fix programme, coordinates the specialist integrator, and keeps the smart-home work on one schedule with everything else, so nothing has to be chased through finished walls later.
Closing CTA
The cheapest time to make a London home smart is during the renovation you're already doing — and the most expensive time is after it's finished. PrimeCraft Surface Solutions builds the cabling and the control wiring into the first-fix stage, coordinates the automation specialist, and prices that work as its own line — working in London and the counties that border it. Book a free site visit, and together we'll map what's worth wiring now so you're not opening walls again later.
