Field note · United Kingdom
No Mobile Signal in a New-Build House? Why It Happens and How to Fix It (UK)
Full bars outside but no signal indoors in your new-build? Why insulation and coated glass block EE, Vodafone, O2 and Three, free fixes, and when a booster helps.
Short answer
New-build homes often have worse indoor signal than older houses because foil-backed insulation boards, energy-efficient coated glass and dense blockwork reflect and absorb mobile signal. If your phone works on the drive but not in the lounge, try Wi-Fi calling first. If that is not enough, a booster (repeater) with an outdoor antenna can bring the outside signal in, provided the model meets Ofcom's requirements.
Why new-build homes block mobile signal
Modern building regulations push builders towards very well insulated homes. That is good for heating bills but bad for radio. Rigid insulation boards (PIR or polyurethane) usually have a foil facing on both sides, and that foil acts like a shield. Many new homes also use double or triple glazing with a metal-oxide coating that keeps heat in and, as a side effect, reflects much of the mobile signal trying to get through the window.
Add plasterboard on metal studs, underfloor heating pipes and a concrete ground floor, and it is common to see four bars on the driveway and one bar, or none, in the kitchen. Estates on the edge of towns can also sit at the fringe of mast coverage.
Step 1: find out where the signal actually is
Turn Wi-Fi off and walk round the house with your phone. Check every room, then stand outside at the front and back and at an upstairs window. Make a real call and load a web page in each spot rather than trusting the bars icon.
Write down which network you are on. In the UK the four networks are EE, Vodafone, O2 and Three, and many brands use them: BT and Plusnet Mobile on EE, giffgaff and Tesco Mobile on O2, VOXI and Talkmobile on Vodafone, iD Mobile and SMARTY on Three. If people in the house use different networks, test each one. Ofcom's mobile coverage checker is a useful second opinion, but your own readings matter more.
Step 2: try the free fixes
If you have broadband, switch on Wi-Fi calling in your phone settings. EE, Vodafone, O2 and Three all support it on most current phones, and your calls and texts then travel over your home Wi-Fi. In a large new-build, a mesh Wi-Fi system may be needed so the Wi-Fi itself reaches every room.
Check that your phone software is up to date and that 4G and VoLTE calling are switched on. If nobody in the house gets indoor signal on any network, report it to your network as well.
Step 3: when a booster kit makes sense
A booster is worth considering when Wi-Fi calling is not enough: for example if you need mobile data on the network, if visitors and family use different networks, if you work from home on calls all day, or if the broadband is not reliable. It works by placing an outdoor antenna where the signal is good, running a cable inside, and rebroadcasting the signal from an indoor antenna.
For a typical three or four-bedroom new-build, a 300 m² class multi-band kit such as our Universal Signal Booster 300 SQM, which lists 700, 800, 900, 1800, 2100 and 2600 MHz, is a sensible starting point. Larger detached homes or houses with a garage conversion and home office may suit a 500 m² class kit. Coverage figures are best-case open-plan numbers, so heavily insulated internal walls may mean adding a second indoor antenna. Prices in our GB shop are shown in pounds sterling (GBP).
Installing in a new-build without damaging the warranty
Most new homes come with a structural warranty, and some estates have covenants about external fixtures. Before drilling, check your paperwork and, if you are still in the builder's snagging period, ask the developer. An outdoor antenna can often be mounted on a fascia, a chimney bracket or a gable end, and the cable can follow the route used by the TV aerial or satellite dish.
Keep the outdoor and indoor antennas well apart, ideally separated by the roof or several walls, so the system does not feed back. Avoid running the cable through cavity wall insulation where you can; use an existing service entry instead.
The rules in the UK
Ofcom allows static indoor mobile repeaters to be installed and used without a licence only if they meet its technical requirements, set out in IR 2102, and it publishes a list of repeaters it understands meet them. Using a repeater that does not meet the requirements is illegal and can cause interference to other people's service.
A product being listed in our shop does not mean it meets those requirements or appears on Ofcom's list, and we make no approval or compliance claim. Check the exact model against Ofcom's current guidance and list, and your network's advice, before you install. We are happy to send the full specifications so you can check them.
Frequently asked questions
Why is my mobile signal so bad in my new-build house?
Foil-faced insulation boards, coated energy-efficient glass and dense construction block a lot of mobile signal. The signal outside may be fine; it simply cannot get through the building fabric.
Will Wi-Fi calling fix poor signal in a new-build?
Often, yes, for calls and texts, as long as your broadband is reliable and the Wi-Fi reaches every room. EE, Vodafone, O2 and Three support it on most modern phones.
What size booster do I need for a new-build home?
Most three to four-bedroom homes suit a 300 m² class kit. Larger homes or houses with a separate home office may suit a 500 m² kit. Send us your floor plan if you are unsure.
Are signal boosters legal in the UK?
Only repeaters that meet Ofcom's IR 2102 requirements may be used without a licence. Check the exact model against Ofcom's requirements and published list before installing.