Why detached buildings are hard
Between your router and a garage or garden office sit two exterior walls (yours and the outbuilding's) plus open air. Modern exterior construction — cavity walls, foil-backed insulation, metal cladding — attenuates WiFi dramatically; foil insulation in particular acts like a partial Faraday cage. This is why a signal that covers your whole house can be unusable ten metres beyond the back wall.
First: measure what actually reaches the building
Before buying hardware, map it. Add your garden and outbuilding to a floor plan in HeatFi, then walk from the house to the outbuilding taking samples along the way and inside it. The heatmap shows one of three situations, each with a different (and differently priced) fix:
| What the map shows | Best fix | Typical cost |
|---|---|---|
| Usable signal inside the outbuilding, just weak | Reposition router toward the back of the house, or a mesh node in the rear room / window | €0–100 |
| Signal dies crossing the garden | Outdoor-rated mesh node or extender on the exterior wall | €80–200 |
| Nothing measurable at the outbuilding | Point-to-point wireless bridge or buried Ethernet run | €100–300 |
The fixes, in order of preference
- Ethernet (wired) run. If there's any conduit or trenching option, a buried outdoor-rated cable to a cheap access point in the outbuilding beats every wireless option for reliability.
- Point-to-point bridge. Two small directional antennas with line of sight between the buildings — effectively an invisible cable, great over 10–100 m.
- Outdoor mesh node. Weatherproof node on the house's rear wall, positioned inside the strong zone your heatmap identified.
- Window-to-window extender. Budget option: an extender in the rear window facing the outbuilding. Glass attenuates far less than wall.
Special case: metal garages and sheds
Metal buildings block WiFi almost completely — signal enters through windows and door gaps only. Put the receiving device (bridge endpoint or AP) outside or at a window, and cover the interior from a small AP inside. Measuring inside a metal shed will show you instantly why the extender-on-the-shelf approach fails.
Quick answers
How far can WiFi reach to a detached garage?
Through two exterior walls, often only 5–15 metres of usable signal — construction matters more than distance. Measure inside the outbuilding with a survey app before buying anything; the result decides between a simple extender and a point-to-point bridge.
What's the best way to get WiFi in a garden office?
For a workspace with video calls: buried Ethernet to a small access point if feasible, otherwise a point-to-point wireless bridge. Both give stable, low-latency links that a repurposed indoor extender can't match through exterior walls.
Will a normal WiFi extender work for a shed?
Only if your heatmap shows solid signal at the extender's position — typically a rear window facing the shed. If the garden itself is a dead zone, an indoor extender has nothing to repeat.
See your WiFi instead of guessing
HeatFi turns your phone into a WiFi survey tool. Draw your floor plan, walk each room, and get a colour-coded heatmap in minutes. Free — no account needed.
