5 UK Van Life Mistakes I See Every Week

After helping hundreds of UK van conversions and reviewing builds across the country, the same five mistakes come up again and again. They're not obvious errors — they're the kind that seem fine until you're three months into your build and realise you need to rip everything out.

Here are the five mistakes I see every single week, why they happen, and exactly how to avoid them.

1. Undersizing the Leisure Battery

This is the single most expensive mistake in UK van life. People buy a 100Ah lead-acid battery thinking it'll power their fridge, lights, and phone charging. It won't — not for more than a day.

A 100Ah lead-acid battery only gives you 50Ah of usable capacity before you damage it. That's roughly 12 hours of LED lights and one phone charge. In reality, a basic UK van setup needs 200Ah minimum if you're running a fridge, water pump, and lighting.

The fix: go lithium from the start. A LiFePO4 battery costs more upfront but gives you 80-100% usable capacity, weighs half as much, and lasts 2,000+ cycles. A 200Ah LiFePO4 unit from Renogy or similar is the minimum for serious UK van life.

2. Skipping the Vapour Barrier

UK vans get cold. When warm, moist air from cooking and breathing hits the bare metal behind your insulation, it condenses. That condensation leads to rust, mould, and a build that's structurally compromised within two winters.

I've seen brand-new conversions with rust forming behind the cladding because the builder skipped a simple vapour barrier. It costs about £30 in polyethylene sheeting and takes an afternoon to install.

The rule: vapour barrier goes between your insulation and interior cladding. Seal every seam with aluminium tape. If you're using spray foam insulation, the foam itself acts as a partial barrier — but you still need to seal around windows and penetrations.

3. Wrong Fuse Sizing

This one's genuinely dangerous. I've seen 12V fridges wired through 30A fuses on 16mm² cable. The fuse will never blow, which means if there's a short circuit, the cable melts before the fuse blows. That's how van fires start.

The correct approach: calculate the actual current draw of each circuit, then size the fuse at 1.5× that draw. A typical 12V fridge draws 3-5A, so it needs a 10A fuse on appropriate cable (minimum 2.5mm² for runs under 3m).

For your main battery-to-leisure-battery link, you need an ANL fuse holder rated at the cable's capacity — typically 80A for a 6 AWG cable or 150A for a 4 AWG cable.

4. Ignoring Ventilation Under the Bed

Every UK van build has a bed. Most builders put storage underneath it. The problem: if there's no ventilation under the mattress, moisture from your body condenses on the cold metal base of the bed and pools. Within weeks, you get mould.

The fix is simple: leave at least 50mm of air gap under the mattress, and ideally install a small vent or louvered panel at each end of the bed frame. Hot air rises, so convection will pull fresh air through the gap and prevent moisture build-up.

This takes five minutes to plan and zero money to implement. Yet I see it missed in almost every build.

5. Not Planning the Electrical Layout First

Most builders start with the fun stuff — building the bed frame, fitting the kitchen unit, choosing colours. Then they realise they need to run cables behind everything they've already built.

The correct order is: stripping → insulation → electrical wiring → flooring → walls → furniture → finishing. The wiring must go in before anything else because you can't easily add cables behind finished walls.

Plan your electrical layout on paper before you touch a single tool. Mark where every light, socket, switch, and appliance will go. Then run all the cables at once. It takes an extra day upfront and saves a week of retrofitting later.

Why These Mistakes Matter

Each of these errors costs between £200 and £2,000 to fix after the fact. Some — like wrong fuse sizing — create genuine safety hazards. The common thread is that they're all preventable with basic planning.

Before you start your build, read through our battery sizing guide, electrical wiring guide, and insulation guide. These three resources cover the technical foundations that most first-time builders get wrong.

The Bottom Line

Van life in the UK is brilliant — but only if your build is solid. Spend a weekend on planning before you spend a penny on materials. Your future self (and your wallet) will thank you.