Will a baby monitor work through two floors in a UK house?

Why do two floors lose more signal than one?

A radio link has to pass through whatever sits between the cot-side unit and the parent unit. One timber floor is usually boards, a void and plasterboard. Two floors stack that twice, and the stairwell is often the only open gap. Which? scores range by walking a parent unit through three rooms and then out to the garden, because indoor figures on the box are not a house test.

Babysense's US help page states its video kit is quoted at 900 feet in open space, then says residential use is different: metal doors, reinforced concrete, thick walls and nearby radios cut the path. That is one storey of separation in US floor names. In a UK house, two floors usually means ground to a second storey or loft — two slabs, not the simple first-night upstairs check.

BT's UK video-monitor help page quotes up to 50 metres indoors and 250 metres outdoors only with a clear line of sight. It lists wall material, thickness, dampness and thick stone as the things that cut that figure.

Timber joists versus a concrete slab

Most Victorian and inter-war houses have timber joists. Angelcare's UK interference note treats wood as one of the easier materials for a signal, and says UK floors are often wood, so a unit above or below can still hear the other end. A 1960s–90s extension, a converted flat, or a poured loft deck can add concrete or a steel beam. Babysense names reinforced concrete in the same breath as large metal objects.

If the first landing already shows a freeze or an out-of-range beep, the second flight is unlikely to recover on its own. Move the cot-side unit before you look at extras. A walk-test before the return window is the same-day check.

How do I walk-test a two-floor house?

Do this with the baby unit where the cot will stand, not on the hallway table. Carry the parent unit; do not judge range from the nursery doorway.

1. 1
   Fix the baby unit Place it at cot height, facing the stairwell if you can do that without putting a mains cable in reach of the cot. The Lullaby Trust says the control unit must stay out of the baby's reach.
2. 2
   Stand on the landing below One floor down. Note picture, sound and whether an out-of-range tone starts. BT says the parent unit beeps when the units are too far apart.
3. 3
   Walk the second flight Kitchen, then the room you actually sit in. Two floors means both flights, not a pause on the first landing.
4. 4
   Garden door last Which? includes an indoors-to-outdoors walk because that is where many kits die. If you use the garden while a baby sleeps upstairs, this is the test that matters.
5. 5
   Move the cot-side unit, not the brand first If the drop is on the first landing, slide the baby unit toward the stair void and repeat. A unit aimed through a chimney breast or a steel beam is a placement problem.

Where should the cot-side unit sit?

The shortest radio path is usually across the stairwell, not through the floor void under the cot. A unit on the street-wall side of a back bedroom may be asking the signal to cross the full depth of the house and two decks.

• Face the stairs if the cable can still sit out of reach of the cot.
• Keep a metre from metal and electrics. BT lists TVs, PCs, routers and microwaves and says to keep them at least one metre from both units. Babysense uses a five-foot / 1.5-metre gap from cordless phones, TVs and dimmers.
• Do not park the parent unit on a radiator or a metal filing cabinet in the kitchen. Angelcare calls metal the main offender.
• A two-up two-down is one floor, not two. Use that page if the nursery is on the first floor and you sit on the ground floor.

The Lullaby Trust's position is that a monitor is not a substitute for an adult in the same room as the baby for the first six months, day or night. Range through floors does not change that.

What does the metre figure on the box actually measure?

Open-space range is a line-of-sight number. Babysense says that is the only common method because every home is different. BT says its 50-metre indoor figure is only reachable in ideal conditions with a clear line of sight, and that any obstruction cuts the range significantly.

A loft-to-kitchen path in a brick house is not that test. If you need a same-day keep-or-return decision, follow the return-window walk-test and write down the first landing, the kitchen and the garden door. A signal booster does not add legal transmit power to a closed parent-unit link.

In shortTwo timber floors can still carry a parent-unit link if both ends face the stairwell. A concrete slab, a steel beam or a chimney stack through the floors is a different path. Walk both flights before the return window; move the cot-side unit toward the stairs before you change kit.