Wi-Fi Not Working in Your New Extension or Loft Conversion? Why, and How to Fix It
7 November 2026 · By Ethan Fernandes
Just finished a kitchen extension or loft conversion and the Wi-Fi barely reaches it? Why new building materials block the signal, and the fixes that work, whether the walls are still open or already plastered.
Quick fix
Foil-backed insulation, steel beams, underfloor heating and energy-efficient glass block Wi-Fi in new extensions. The best fix is a network cable to an access point or mesh unit in the extension. If it's already finished, place a mesh unit halfway, run a discreet cable through the loft or floor, or try powerline. Avoid plug-in extenders.
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Get help todayIt's one of the most common complaints after building work: a beautiful new kitchen extension or loft conversion, and the Wi-Fi drops to one bar or nothing at all. The smart speaker won't connect, video calls freeze and the TV buffers.
It isn't bad luck. The things that make extensions warm and bright are the same things that block Wi-Fi.
The short version: modern insulation, steel beams, underfloor heating and energy-efficient glass block Wi-Fi, and the router is usually at the opposite end of the house. The best fix is a network cable to a Wi-Fi access point or mesh unit in the extension. If the walls are already plastered, a mesh system placed carefully, or powerline adapters, are the next best options.
Why Extensions Kill Wi-Fi
- Foil-backed insulation boards in walls, floors and roofs act like a shield.
- Steel beams where walls were knocked through.
- Underfloor heating and thick screed between floors.
- Energy-efficient glazing in bifold doors and roof lanterns, which has metallic coatings.
- Distance: the router is often by the front door, where the line comes in.
If the Walls Are Still Open: Run a Cable
If you're mid-build, this is the moment. Ask the electrician to run a Cat6 cable from the router position to a ceiling point in the extension for a Wi-Fi access point, and to the TV and any desk. It's quick now and disruptive later. See our renovation network checklist.
If It's Already Finished
- Move the router if you can, closer to the middle of the house.
- Mesh Wi-Fi: put one unit halfway between the router and the extension, where it still gets a strong signal, and another in the extension. See is mesh Wi-Fi worth it?
- A cable the discreet way: often a cable can be run through the loft, under floorboards or along skirting boards without damage.
- Powerline adapters send the network through the electrics. They can work, but extensions are sometimes on a separate circuit, which reduces speed.
- Avoid plug-in extenders, which usually halve the speed and add drop-outs.
Loft Conversions
Lofts have the same insulation problem, plus a floor or two between them and the router. A cable up through a cupboard to an access point or mesh unit on the loft landing usually fixes it.
How We Handle It
We test the signal through the house, find what's blocking it, and fix it with the least disruption: a discreet cable to an access point, a properly placed mesh system, or a combination. If you're still building, we plan it with your builder before the walls close. We work across West London. See our Wi-Fi and home networking and renovation tech planning.
Related Reading
Common questions
Foil-backed insulation, steel beams, underfloor heating and energy-efficient glass block Wi-Fi, and the router is often at the other end of the house. A cabled access point or well-placed mesh unit in the extension fixes it.
Best is a network cable from the router to a Wi-Fi access point or mesh unit in the extension. If that's not possible, use a mesh system with a unit placed halfway, or powerline adapters. Avoid plug-in extenders.
Foil-backed insulation boards, common in modern extensions and loft conversions, block Wi-Fi very effectively. Steel beams and energy-efficient glass also reduce the signal.
Rarely well. Extenders repeat a weak signal, often halving the speed. A mesh system or a cabled access point gives far better results.
Still stuck? We can fix it for you
Most problems like this can be fixed remotely today, anywhere in the UK, or with a home visit across West London. DBS checked, insured, 7 days a week until 9pm.
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