Wi-Fi in the attic or loft conversion: why it's so weak
The new loft bedroom or office looks great, and has one bar of Wi-Fi. It's the room furthest from the router, and it's often wrapped in materials that block radio.
A loft conversion is a popular way to add a bedroom or an office. It's also, almost always, the room furthest from the router: at the top of the house, often at one end. And the way attics are insulated can make it worse.
Why attics are hard
- Distance and floors. If the router is on the ground floor, the attic is two floors up, at a steep angle through two slabs. See Wi-Fi weak upstairs.
- Foil-backed insulation. Many modern insulation boards and membranes under the roof have a reflective aluminum layer. It keeps heat in, and also bounces Wi-Fi back out. If the conversion added insulation in the floor too, the whole room can sit inside a metal-lined box.
- Sloped ceilings, knee walls and storage. Signal that manages to get up has to pass through built-in cupboards and the lower walls under the slope.
- The stairs are narrow. The attic staircase is usually a small opening compared with a main stairwell.
Fixes that work
- Move the router up and toward the middle, as close as practical to the attic stairs. From the first floor, the attic is only one floor away.
- A mesh node on the floor below, near the attic staircase, where it still hears the router well. It will cover the attic through the stair opening better than through the floor.
- Wire the attic. During a conversion is the moment to pull an Ethernet cable up. Afterwards, look for existing routes: service risers, old chimney voids, cupboards stacked above one another. An access point or wired mesh node in the attic solves it for good. See wired backhaul for mesh.
- Powerline if a cable can't go up. Attics are often on their own circuit, so test before relying on it; see powerline.
What not to do
- Don't put an extender in the attic itself to repeat a router it barely hears through foil and two floors.
- Don't assume a stronger router will get through the insulation. Metal layers don't care much about power.
Map the attic as its own floor
WiFi Heatmap lets you map each floor separately, including the attic. Map it before and after moving the router or adding the node, and look at the whole room, not just the spot by the stairs: the far end under the slope is usually where the difference shows. For node placement, see where to put a mesh node.