Every spring my phone starts ringing about the same thing: a brand-new garden office at the end of the lawn, beautiful joinery, underfloor heating, foil-backed insulation, and exactly two bars of WiFi if you stand on a chair near the window. The owner has usually already tried a plug-in extender, a mesh node propped on the patio, and a long flat ethernet cable run under the doormat. None of it works the way the box promised. The honest answer for WiFi garden room London projects is almost always the same: a buried outdoor-grade ethernet cable, a small PoE switch inside the house, and a proper access point mounted in the outbuilding. Once that is in, the problem goes away for good.

I have been wiring up London houses since 2011, and the garden-room boom of the last few years has changed the shape of my week. Architects' studios in Stoke Newington, prefab pods in Wandsworth, recording rooms in Highgate, yoga studios in Chiswick, a tiny gin-distilling shed in Forest Hill — they all need network and they all hit the same wall. The garden looks short until you start trying to push 5 GHz through a brick external wall, fifteen metres of damp air, and then a foil-backed SIP panel. Below is everything I tell clients before I quote, plus the three or four ways I see this go wrong every month.

Why a wireless bridge from the indoor router almost always disappoints

Nine out of ten people start with the same plan: leave the router where it is in the front hall, buy a mesh satellite or an outdoor extender, point it at the garden room, and hope. On paper the manufacturer's range chart says fifty metres line of sight, so a twenty-metre garden should be comfortable. In practice the signal has to leave the house, and that means punching through an external wall — usually solid London brick, often two skins of it, sometimes with a cavity full of mineral wool or PIR board. 5 GHz, which is where the speed lives, loses a huge amount of energy through every one of those layers. By the time it reaches the garden the signal-to-noise ratio (SNR) is so poor that even if your phone shows a bar or two, real throughput collapses to a trickle.

Then the signal has to get into the garden room. Modern outbuildings are built like flasks: timber frame, dense PIR insulation, often with a reflective foil facing on the inside of every panel, sometimes a standing-seam metal roof on top. That foil is essentially a Faraday cage. I have stood inside finished pods where a phone hard up against the inner wall reads good signal, taken two paces toward the middle of the room, and watched it drop to nothing. I wrote a longer piece on this at what actually blocks your WiFi signal — foil-faced insulation is the headline villain. No amount of pretty marketing on a flashy mesh kit overcomes physics.

The "just stick an extender in the kitchen" trap

The cheap fix everyone tries is a plug-in extender or powerline adaptor on the kitchen ring closest to the garden. It picks up the indoor WiFi, halves the bandwidth re-broadcasting it (that is how a single-radio extender works), and the second hop into the garden room is even worse than the first. Powerline kits sometimes do better, but only if the kitchen and the garden room are on the same ring main with a clean neutral. In most London houses they are not — the garden feed often comes off a spur, sometimes from a separate consumer unit, and the high-frequency carrier the powerline uses gets attenuated to nothing. I cover the deeper reasons in why WiFi boosters and extenders almost always disappoint. The short version: do not throw good money after bad.

Distance: under 25 metres versus over 30

Cable choice and installation depth are driven mostly by run length and how the route gets out of the house. I split jobs roughly into two bands:

  • Sub-25 metre runs. Most London terraces and semis. A single continuous run of outdoor-grade Cat6 or shielded Cat6 in 20 mm flexible conduit is plenty, and the cable comfortably stays within the 100 m channel limit that ethernet specifies. PoE will deliver full power to a ceiling-mount access point without breaking a sweat.
  • 30 metres and beyond. Long Georgian gardens in Highgate, Belsize Park or Dulwich, plus anything where the cable has to take the long way round a side-return extension. Still fine for gigabit ethernet on Cat6 — the standard supports 100 m — but I start being fussier about cable quality, drainage at the ends, and gel-filled glands where the cable enters the building. For runs creeping past 80 m I prefer Cat6a so I have headroom for 2.5 G or 10 G WiFi 6E and 7 access points in future.

For runs over 100 m — which does happen, country-style plots in Hampstead and Wimbledon — the answer is either a fibre run with a media converter at each end, or a mid-span PoE injector built into a small weather-rated enclosure. I will never daisy-chain two long ethernet patches together to dodge the limit; the certification will not pass and the link will be flaky under load.

The proper way: structured cable + PoE switch + access point

The pattern I install almost every week looks like this:

  1. An outdoor-grade Cat6 (or shielded Cat6, F/UTP) cable, run from a tidy point inside the house — usually next to the router, often on or near the BT master socket if the router lives there.
  2. The cable leaves the wall through a fresh, properly sealed core hole — never threaded under a door frame or stapled to the skirting.
  3. It runs in flexible black UV-stable conduit, ideally buried at spade depth where it crosses lawn, or clipped neatly to a fence run where burial is impossible.
  4. It enters the garden room through a sealed gland, low down at the back so it never gets snagged.
  5. Inside the house, that cable terminates on a Keystone module and patches into a small PoE switch — eight ports is plenty for most homes — which sits next to the router.
  6. At the garden room end, the cable terminates on a second Keystone, then a short patch lead feeds a ceiling- or wall-mount 802.11ax (WiFi 6) access point.
  7. If the client wants wired drops at the desk, a smart TV, a printer or a games console, I run additional Cat6 from the AP location to one or two flush wall plates inside the garden room.

The advantages stack up: the AP has unlimited backhaul because it is wired, PoE means one cable carries data and power so no electrician is needed at the AP, and the broadcast inside the garden room is a fresh, local signal sitting under the foil layer rather than fighting against it. Real-world throughput inside the outbuilding ends up matching whatever the indoor WiFi gives you — often better, because the AP is closer and there is less interference from neighbours. I always certify the finished link with a Fluke tester so the client has a printable report showing the cable passes its category at full length.

Why outdoor-grade matters

Standard internal Cat6 has a PVC jacket that degrades quickly in sunlight and goes brittle in frost. Within eighteen months an above-ground internal cable will start cracking, water will wick in along the conductors, and the link will fail at random. Outdoor-grade cable has a UV-stable LDPE jacket and is rated for direct burial; gel-filled variants are better still, particularly for clay London soils that hold water. The few extra pounds per metre buys a cable that will still be working in fifteen years.

PoE access points: what to choose and where to mount

For most domestic garden rooms I fit a single ceiling-mount 802.11ax AP from a reputable enterprise range — the same kind of unit I would put in an office. WiFi 6 is the right floor at this point; the speeds and the simultaneous-client handling are noticeably better than older WiFi 5 kit, and most family devices made since 2020 support it. Tri-band WiFi 6E is worth specifying if the room is going to host video editing, large file syncs, or a serious home-office setup.

Mounting matters more than people think:

  • Ceiling centre, omnidirectional pattern, broadcasting downwards — almost always the right choice for a single-room studio.
  • Wall-mount with a directional pattern if the building is long and thin, so coverage reaches the desk at the far end rather than wasting energy on the wall behind the unit.
  • Never inside a metal-lined cupboard or behind a TV — the foil-and-metal effect of those locations turns a serious AP into a feeble router.

The deeper trade-off between AP-style installs and consumer mesh kit lives in mesh WiFi vs wired access points. For an outbuilding, wired wins every time.

Three real-world scenarios

1. Architect's garden studio, Stoke Newington — 25 m and a metal roof

A practising architect called me after working from a beautiful new studio for a fortnight and losing every important video call. The pod sat twenty-five metres down a long Hackney garden, timber-clad, with a standing-seam zinc roof and PIR insulation throughout. She had tried a mesh satellite on the kitchen window sill — utterly useless past the back wall. I ran an outdoor F/UTP Cat6 from a PoE switch next to her FTTP ONT in the hallway, out through a new core hole into a side return, up the boundary wall in conduit, then buried across the last twelve metres of lawn to the studio. At the studio end I fitted a WiFi 6 access point on the ceiling and put a single wired desk drop next to her monitor for video calls. Certification passed at gigabit. She rang the next week to say a Teams call had finally not collapsed in mid-sentence.

2. Pre-fab garden room, Wandsworth — foil-backed walls and ceiling

A family in Wandsworth had bought one of the popular prefab pods, the kind that arrives on a lorry and is craned over the house. Lovely thing — and completely opaque to WiFi. Both walls and the ceiling were lined with reflective foil-faced PIR. A consumer mesh node sitting just inside the back door of the house registered a strong signal at the pod's window and absolutely nothing two paces inside. We ran shielded Cat6 along the existing fence line in UV-rated conduit, buried the last few metres under the gravel path, and terminated to a PoE-fed AP mounted dead centre on the pod ceiling. Inside the pod the signal is now indistinguishable from the main house — because the AP is broadcasting inside the foil, not trying to push through it. The job also got the family a tidy ethernet drop next to the desk, which their teenager uses for online gaming.

3. Detached outbuilding, Highgate — a music studio that needed PoE

A music producer in Highgate had converted a detached brick outbuilding at the back of his garden into a recording room. Thick walls, acoustic treatment, a single mains feed and no spare sockets. He wanted reliable internet for stem deliveries and absolutely no buzz or hum on the audio path. Running mains for a separate router inside the studio was off the table — he did not want another transformer near his pre-amps. PoE solved it: one outdoor Cat6 from the house, terminating to a ceiling-mounted AP, no mains adaptor needed at all. Switch-side I fed it from a small managed PoE switch indoors so I could throttle and monitor the link. The studio now has a clean, quiet, gigabit-capable network and one fewer power supply near the desk.

What I will not do, and why

People sometimes ring asking me to "just put a powerline kit in" or to "set up a long-range outdoor extender on the back wall." I will quote for these on the rare occasions where they are genuinely the right answer — a listed building where no cable can be run, for example — but I will say plainly that they are second-best, and I will not certify them as a permanent install. The same goes for stringing flat ethernet cable across a patio, leaving cable lying in a gutter, or feeding a cable through a UPVC window frame. None of those will survive a London winter. If a job cannot be done properly I would rather walk away than leave a client with a fix that fails in nine months.

Buried, clipped or fence-run? The route matters

How the cable travels from the house to the garden room is half the job. There are usually three honest options:

  • Buried in conduit across the lawn. Tidy, invisible, future-proof. Best for finished gardens where the grass can be lifted and relaid neatly, or where there is a soft border running the right way.
  • Clipped along the fence or boundary wall. Faster, cheaper, no excavation. Always in UV-rated conduit, clipped at sensible intervals, with drip loops so water cannot track inside. The trade-off is visibility; on a tasteful garden it may not be welcome.
  • Side-return overhead in cable tray. Useful where there is an existing gas or electrical run we can shadow. Always above head height, always in conduit, and always entering the garden room through a sealed gland.

What I will not do is run unprotected cable along a fence with clips alone, or punch through a window frame. Both fail inspections and both fail in winter.

Optional: wired drops inside the outbuilding

Once the cable is in and the AP is up, adding a couple of wired ethernet points inside the garden room is a cheap addition while the kit is open. I always offer it. A wired drop behind the desk is the difference between a video call that just works and one that hiccups when the kids upstairs start streaming. For anyone running a serious home office, a Sonos system, a smart TV or a console, the wired drop is the part they end up using most. I cover the practicalities in detail on the ethernet cable service page.

How a typical visit runs

A garden-room WiFi job usually takes me a single working day, sometimes two if the cable route is long or the lawn needs careful lifting. I will:

  1. Survey the route on arrival, agree the entry and exit points with the client, and check the existing router and master socket setup so the indoor end is tidy.
  2. Drill, sleeve and seal the core hole at the house wall.
  3. Run, dress and protect the cable along the agreed route, in conduit, with drip loops and proper strain relief.
  4. Terminate both ends on Keystones, fit the AP, configure SSIDs to match the main house so devices roam seamlessly, and test.
  5. Certify the cable with a Fluke tester and leave a printable report.
  6. Tidy up — backfill any trench, replace turf, wipe down everything I touched.

If the indoor setup is messy — old extension leads, a router stuffed behind a bookcase, a master socket on the wrong side of the room — I will usually tidy that at the same time. The can I move my master BT socket guide covers what is and is not allowed there, and the London broadband engineer page lists everything else I do on the broadband side.

The questions I get asked most

Can you not just use a long ethernet cable from inside?

You can — for a short, indoor-only run. The moment that cable is exposed to UV, rain or frost, you are on borrowed time. Outdoor-grade cable costs very little more and lasts a decade or more.

What about a point-to-point wireless bridge?

They have a place — listed buildings, party walls, sites where no cable can be dug or clipped. For a standard London garden where a cable can be run, a wired bridge is always better. Wireless bridges add latency, hate rain, and depend on perfect line of sight between two dishes mounted high on each end. They are not a free upgrade.

Will it work with my existing router?

Yes. The PoE switch and the new AP sit alongside your existing router, taking an ethernet feed from one of its LAN ports. Your SSID and password stay the same; the new AP just adds proper coverage where there was none. If you want a survey before committing, the WiFi heat-map survey piece explains what that visit looks like.

Ring 020 3633 1131. Honest advice, freely given.