A campervan can look lightly loaded while exceeding its legal total or an individual axle limit. Batteries, water, gas, bikes, passengers and conversion furniture add up quickly. The useful number is not a seller's vague “empty weight”; it is the finished van's measured travelling weight compared with the limits on its plate.
This guide explains the planning method for an Irish-registered campervan. The vehicle plate, registration details and your driving licence remain the deciding documents.
The four numbers to separate
| Term | What it tells you | What to do with it |
|---|---|---|
| MAM / DGVW | The maximum authorised or design gross vehicle weight: vehicle plus its permitted load. | Find it on the vehicle plate and registration evidence. Do not exceed it. |
| Actual laden weight | What the complete campervan weighs in the configuration presented to the weighbridge. | Measure it with the people, water, fuel and equipment representative of travel. |
| Payload remaining | MAM minus the actual travelling weight. | Treat this as a shared allowance for everything still to be added. |
| Axle limit | The maximum permitted load on a particular axle. | Check front and rear readings as well as the total; a legal total can still hide an overloaded axle. |
The 3,500kg Irish licence boundary
The RSA says a category B licence covers a campervan with a maximum authorised mass not exceeding 3,500kg, with no more than eight passenger seats in addition to the driver. A campervan above 3,500kg moves beyond category B; the RSA identifies category C1 for vehicles over 3,500kg and up to 7,500kg, subject to the category's conditions.
The licence test is based on the vehicle's authorised maximum, not the fact that it happens to be lightly loaded today. If the plate says 3,850kg, weighing the vehicle at 3,400kg does not make it a category B vehicle. Check the categories printed on the physical licence and any restriction or expiry dates rather than relying on when the holder first learned to drive.
A practical payload calculation
Suppose a finished campervan has a plated MAM of 3,500kg and weighs 3,080kg at a weighbridge with the driver, 90% fuel and the normal fixed equipment aboard. The apparent remaining payload is:
3,500kg − 3,080kg = 420kg.
That 420kg must still absorb whatever was absent: passengers, drinking and waste water, food, clothes, gas, bedding, bicycles, an awning, tools and accessories. A 100-litre fresh-water tank can hold roughly 100kg of water before allowing for the tank itself. Rear-mounted bikes and boxes can also put a disproportionate share of load on the rear axle.
Do not subtract brochure “kerb weight” from MAM unless the maker defines exactly what the quoted figure contains and it matches the finished vehicle. A self-build's cabinetry, insulation, wiring, heater, leisure batteries and solar installation may all have been added after the base-vehicle figure was published.
How to get a useful weighbridge reading
- Finish the conversion first. Include permanent fixtures, fitted gas cylinders, batteries, spare wheel and accessories.
- Choose a realistic travel state. Record fuel, fresh water, waste water, occupants and removable kit so the result is repeatable.
- Measure the complete vehicle. Ask for a dated ticket showing the registration and total weight where available.
- Measure each axle. Position only the relevant axle on the platform if the operator permits it, following the operator's directions.
- Compare all limits. Check the measured total against MAM and each measured axle against its plated maximum.
- Reweigh after material changes. A second battery, towbar, bike rack, larger water tank or new furniture can erase a narrow margin.
Payload planning sheet
| Item | Weight to enter | Evidence |
|---|---|---|
| Measured vehicle in stated condition | _____ kg | Weighbridge ticket |
| People not present at weighing | _____ kg | Actual combined weight |
| Additional fresh water | _____ kg | Litres added, approximately 1kg per litre |
| Food, clothing and personal kit | _____ kg | Scale or conservative estimate |
| Bikes, rack, awning and outdoor kit | _____ kg | Manufacturer data or scale |
| Remaining margin below MAM | _____ kg | MAM minus planned total |
Keep a genuine buffer. Travel conditions change, scales have tolerances, and it is easy to add supplies during a trip. If the calculation only works with an empty water tank or no passenger luggage, the layout or plated weight needs another look.
Distribution matters, not just the total
Heavy items should be secured and, where the conversion design allows, kept low and between the axles. Loading everything into a rear garage can breach the rear-axle limit even when the vehicle is under 3,500kg overall. It can also affect steering, braking and stability. Do not move a load merely to manipulate one weighbridge reading if it cannot be safely restrained in normal use.
Towing adds another layer: the vehicle's towing limit, train weight, trailer MAM, nose weight and the driver's trailer entitlement all matter. Use the vehicle manufacturer's plate and RSA's current towing guidance for the specific combination; the campervan's unused payload is not automatically extra trailer capacity.
Questions to settle before buying or converting
- What MAM and axle limits are on the physical plate?
- Which licence category does each intended driver actually hold?
- Is the quoted weight measured after conversion, and what did it include?
- What are the front and rear axle readings in touring condition?
- How much margin remains with all passengers, water and normal equipment?
- Has a later accessory changed the figures?
Official sources
- RSA: licence categories for campervans and towing
- RSA: driving-licence vehicle categories
- RSA Rules of the Road: vehicle weight and overloading
This is a planning guide, not a vehicle classification or licence-entitlement decision. Resolve any mismatch with the RSA, NDLS and the vehicle's official documentation before driving.