Rooflights, Vents and Blinds: How to Get More Air and Light into Your Van

Ventilation & Daylight Guide

A practical guide from Bedam Leisure — caravan & motorhome specialists

Ask most owners what they'd change about the inside of their van and you'll hear the same two things: it's darker than they'd like, and it gets stuffy. Both problems are solved in the same place — the roof. A tired, yellowed rooflight and a vent that hasn't turned since 2015 are quietly costing you daylight, fresh air and, in a British autumn, a fair bit of dry air too.

September is a sensible time to sort it. The touring season is easing off, the weather is still dry enough to work outside, and anything you improve now pays you back all winter when condensation becomes the real enemy. Here's how we'd go about it.

Rooflight, vent or fan — what's the difference?

These three words get used interchangeably and they shouldn't be. A rooflight (or roof window) is primarily about daylight — a clear or tinted acrylic dome that lifts on struts or a handle, usually with a blackout blind and a flyscreen built into the inner frame. A roof vent is the same idea with the emphasis on airflow rather than light: smaller, often opaque, sometimes with permanent fixed ventilation built in. A powered fan adds a 12V motor so you can move air even when the van is parked in still, humid conditions — which is most of a UK autumn.

Most vans want a mix. Daylight over the lounge, extraction over the kitchen and the washroom. Putting a fan where you actually cook and shower does far more for damp than another rooflight over the sofa.

1 Measuring

The two numbers you must get right

Almost every wrong-part return we see on rooflights comes down to one of two measurements, and neither is the size of the dome you can see from the ground.

The cut-out. This is the hole in the roof, not the outer frame. The industry standard is 400 × 400 mm — if your van has a square rooflight, it's very probably that. Larger units run to 700 × 500 mm and 900 × 655 mm. Measure the aperture from inside, at the inner frame, and measure both directions.

The roof thickness. This is the one people forget. The same model is sold in different versions to suit different sandwich-panel thicknesses — typically a 25–42 mm version and a 43–60 mm version — because the frame has to clamp the panel between it. Order the wrong band and it simply will not tighten down properly. Measure at the aperture edge with a steel rule, and if you're between bands, measure again in a second corner.

Measure before you order, not after. Take your two numbers and a photo of the existing inner frame. If a rooflight is on its way out, do this on a dry day now rather than in the dark with a leak above the bed.

2 Daylight

Going bigger for light

If the goal is genuinely brighter living space rather than just fresh air, size matters more than anything else. Stepping up from a 400 × 400 to a 700 × 500 roughly doubles the glazed area, and in a lounge it changes the feel of the van completely — particularly on grey October afternoons when the side windows are doing very little.

The trade-off is that a bigger aperture is a bigger job. It's a cut, not a swap, and it needs a competent installer who knows how to seal a sandwich panel properly. Plan it as a winter workshop job rather than a Sunday afternoon.

3 Airflow

When a powered fan earns its keep

Opening a rooflight relies on wind. On a still, damp evening on a sheltered pitch there isn't any, and that's precisely when moisture from cooking, kettles and breathing has nowhere to go. A 12V fan solves that in a way no passive vent can.

Two things to look for. First, reversibility: being able to extract moist air out of the washroom or kitchen, then reverse to draw cool air in on a warm afternoon, makes one fan do two jobs. Second, a built-in rain shield, so you can keep ventilating through a shower without water coming in — the single feature that gets the most use in this country.

Already have a Fiamma Vent 28? You don't necessarily need a whole new unit. The Kit Turbo-Vent 28F (£97.99) adds a 12V powered fan to an existing Fiamma Rooflight Vent 28 — a far cheaper route to forced airflow.

4 Control

Blinds, blackout and keeping heat where you want it

Glazing in the roof is wonderful for light and terrible for insulation. On a clear winter night a bare rooflight is the coldest surface in the van, which is exactly why condensation forms on it first and drips onto the bed at four in the morning. On a hot afternoon the same panel turns the van into a greenhouse.

A pleated blackout blind handles the light and the privacy. An insulating cover handles the heat — in both directions. If you only do one small job on the roof this autumn, fitting a thermal cover over the rooflight above your bed is the one that pays back fastest.

Rattle or drumming at speed? A Fiamma Universal Spoiler (£39.99) fits ahead of the rooflight and can be trimmed to size — it cuts vibration and wind noise on the move, and takes some of the buffeting off the dome.

The one rule you should never bend

Caravans and motorhomes are built to European habitation standards, and a fixed amount of permanent, unpowered ventilation is part of that — split between high level (usually the roof) and low level (small floor-level vents). BS EN 721 covers the safety ventilation requirements for leisure accommodation vehicles, and the reason behind it is simple: gas appliances and heaters need air, and carbon monoxide has to have somewhere to go.

So when the nights turn cold, do not tape over, foam-fill or permanently cover your fixed vents to cut draughts. If the van feels cold, the answer is insulation, a thermal cover over the glazing, and a properly working heater — never less ventilation. And if you're fitting a new unit, make sure you don't end up with less permanent ventilation than you started with. A working carbon monoxide alarm to EN 50291-2 belongs in every van as well.

While you're on the roof: check the sealant line around every rooflight and vent. Hairline cracks and shrinkage at the corners are how roof leaks start, and a damp roof panel is a far more expensive repair than a new rooflight. Worth doing before your damp check.