How to Plan WiFi Coverage for a 3-Bedroom Apartment (Without a $5k Tool)

The example layout we'll use

We'll plan a real-ish apartment: 100 m², roughly 13 m long by 8 m wide, three bedrooms along one side, a corridor down the middle, kitchen and living room at the other end. Interior walls are solid brick (this is a Southern European / older building reality — in the US they're more likely to be drywall, which changes the answer). One exterior wall has a balcony with a glass door.

The rule of thumb we'll work from: one consumer AP at 20 dBm typically covers 60–80 m² of drywall-divided space at 5 GHz. Brick is roughly 3× the attenuation of drywall per wall, so for brick that drops to maybe 40–55 m² of usable 5 GHz coverage per AP. Hence: two APs for 100 m² of brick interior is the default starting point.

Step 1 — Get a floorplan and measure something

You need a floorplan image (PNG, JPG, or a screenshot of a PDF page). If you bought the place, you have one. If you didn't, sketch one on paper, photograph it, and that's fine. It doesn't need to be architectural-grade — predictive RF math is roughly ±6 dB anyway, and ±0.5 m on a wall placement doesn't change the heatmap meaningfully.

You also need one known measurement. Tape-measure the long wall of one room, or use the doorway width (interior doors in the EU are usually 80 cm, US 32"). This is for calibration — without it, the tool doesn't know whether your image is 5 m wide or 50 m.

Open the editor, upload the floorplan, and enter your known measurement in the calibration field. The tool computes pixels-per-meter from there.

Step 2 — Decide on the number of APs (before you draw anything)

It's tempting to start drawing walls first. Don't. Decide AP count from area and material first, then validate with the heatmap. The rough heuristic:

For our 100 m² brick example: start with two. We'll validate with the heatmap.

Step 3 — Draw walls by material

In the editor, walls have a material picker. The defaults follow ITU-R P.2040:

• •Drywall: ~3 dB at 5 GHz. Single sheet on metal studs.
• •Glass: ~2 dB. Yes, glass blocks less than drywall.
• •Brick: ~8 dB. Solid clay brick or hollow brick, indistinguishable for our purposes.
• •Concrete: 12–15 dB. Reinforced concrete (rebar inside) is even worse — closer to 20 dB. The model uses 12 as a conservative default.

For our example: draw the exterior walls as concrete (apartment buildings usually have a reinforced concrete shell), all interior walls between rooms as brick, the bathroom-to- bathroom wall as concrete (load-bearing in most EU buildings), and the balcony door as glass. You don't need to draw closets or interior trim — they don't materially affect the propagation budget.

A practical shortcut: if you don't know whether a wall is brick or concrete, knock on it. Concrete is solid and dead-sounding. Brick is solid but slightly hollow. Drywall sounds obviously hollow and yields if you push.

Step 4 — Place the APs

Drop two APs from the preset library (UniFi U7 Pro and U6+ are reasonable picks for a home lab — but vendor doesn't matter much at this stage). Where to put them:

• •Don't put them in corners. Half the radiated power goes into the wall behind. A corner AP is roughly half an AP.
• •Put them on opposite sides of the apartment, ideally roughly 2/3 and 1/3 along the long axis. For our 13 m apartment: one near the living room ceiling (~4 m from one end) and one near the master bedroom doorway in the corridor (~9 m).
• •Ceiling-mount if you possibly can. A shelf-mounted AP fires into the floor and ceiling, wasting half the energy. Ceiling-mounted, it fires down into the rooms.
• •Avoid placing an AP directly next to a concrete load-bearing wall. One direction of coverage just dies.

Step 5 — Read the heatmap

The editor renders predicted signal strength as a coloured overlay. Mental model for the bands:

• •Green (above −60 dBm): excellent. Full speed, low latency, no roaming issues.
• •Yellow (−60 to −70 dBm): good. Video calls fine, 4K streaming fine.
• •Orange (−70 to −80 dBm): marginal. Connected, but throughput drops fast. Anything more than one brick wall away is here.
• •Red (below −80 dBm): dead zone. Phones will keep trying to associate but performance is terrible.

For a home, aim for yellow or better in every room you actually use. The toilet doesn't need −55 dBm. The home office does.

If the heatmap shows a red corner — typically the bedroom furthest from both APs, behind two brick walls — try dragging the nearer AP a metre closer to it. The heatmap updates live. If you can't get yellow into that corner without dropping coverage elsewhere, you need a third AP (or a wired backhaul to an extender there).

Step 6 — Sanity-check with reality

Predictive heatmaps are not exact. They model walls and free-space loss; they don't model furniture, multipath, your fridge, the dishwasher's metal cavity, or how your neighbours' APs interfere on channel 6. Expect ±6–10 dB compared to a real survey.

After you install, do a 10-minute walk-around with WiFiman, the UniFi app's signal meter, or any phone-side scanner. Stand in each room for 30 seconds and note the dBm. If reality is within 8 dB of the prediction, you nailed the placement. If you're off by 15+ dB in a specific spot, something's there that you didn't model — usually a metal door, a mirror, or a built-in metal-backed appliance.

Common mistakes

• →Putting both APs in the same room. Two APs three metres apart give you twice the channel utilisation, not twice the coverage. Spread them.
• →Forgetting the kitchen. Kitchens have metal appliances, often a backsplash that reflects badly, and they're usually load-bearing-walled. Plan around them.
• →Cranking Tx power to 23 dBm "to be safe". Your phone still transmits at 15 dBm. The link is asymmetric — the AP hears the phone worse than the phone hears the AP. High Tx power just creates dead zones with one-way connectivity. Leave it at 17–20 dBm.
• →Skipping 2.4 GHz. Your IoT garbage (cheap smart bulbs, doorbells) is 2.4-only. Plan both bands. Most consumer APs do this automatically; check the heatmap on the 2.4 tab too.