Why is proper load securing on the roof rack important?

For many drivers, transporting luggage, sports equipment, or work materials on the car roof is part of everyday life. Whether it's a roof box, bike rack, canisters, camping gear, or tools – additional storage space on the roof is often used to relieve the interior of the vehicle.

But this is precisely where an important point lies: Safety does not end when items are loaded. Loads on the roof must be properly secured – and not just the contents themselves, but also the system on which the load is transported.

This means that the vehicle, attachment points, crossbars, roof box or platform, and the actual load must be considered as one coherent system.

Loads on the roof are exposed to stronger forces

Many drivers underestimate the forces that act on items on the roof while driving. Even if the load appears stable when stationary, the situation changes significantly during operation.

While driving, the load is subjected to, among other things:

• Air currents at higher speeds

• Vibrations from the road surface

• Acceleration and braking forces

• Lateral forces in curves

• Crosswinds on highways

• Shocks from road unevenness

These forces can cause poorly secured loads to shift, loosen, or even completely detach from the vehicle.

Roof boxes are also part of load securing

Many drivers use roof boxes as a seemingly simple solution: mount the box, put things in, close the lid – done. In reality, the situation is a bit more complex.

A roof box is first attached to the crossbars. Only then does it transport the load inside. In this sense, the roof box itself is also part of the load on the roof.

This means:

• The roof box must be correctly mounted on the crossbars

• The attachment must match the shape and position of the crossbars

• The maximum roof load of the vehicle must not be exceeded

• The weight should also be distributed sensibly inside the box

A closed roof box therefore does not automatically mean that the load is secure.

The role of crossbars and roof rack systems

Crossbars form the basis of any roof transport solution. Roof boxes, bicycle holders, ski racks, or platforms are mounted on them.

They perform several tasks:

• Bearing the weight of the load

• Transferring forces to the vehicle structure

• Stabilizing the entire roof structure

• Absorbing aerodynamic loads during travel

If crossbars are incorrectly mounted, do not fit the vehicle geometry, or are overloaded, this can lead to problems – from increased noise to structural damage.

Therefore, it is worth paying attention not only to accessories like roof boxes but also to the quality and stability of the roof rack system itself.

Platforms and open loads

In addition to roof boxes, platform roof racks are increasingly being used. They enable the transport of a wide variety of items, for example:

• Canisters

• Luggage boxes

• Camping equipment

• Spare tires

• Tools

• Ladders or longer components

The advantage of such platforms lies in their flexibility. At the same time, however, the driver's responsibility also increases, as open loads must be secured particularly carefully.

Lashing straps or special fastening systems are often used here. It is important that the load cannot move in any direction.

Modular systems – such as Airholder – offer various attachment points for this purpose and allow flexible adaptation to different transport tasks.

Legal responsibility of the driver

In Germany, Section 22 of the Road Traffic Act (StVO) regulates load securing. It states, in essence, that loads must be secured in such a way that, even in the event of full braking or sudden evasive maneuvers, they:

• do not slip

• cannot tip over

• cannot fall off

• do not cause avoidable noise

• do not impair road safety

Important: The responsibility always lies with the driver.

Even if roof racks, roof boxes, or accessories have been correctly mounted, the driver must check before each journey whether the load is securely fastened.

Common mistakes with roof loads

In practice, similar mistakes occur repeatedly:

• Roof box is not tightened completely

• Load inside the box is unevenly distributed

• Crossbars are too weak or incorrectly mounted

• Lashing straps are not sufficiently tightened

• Weight is concentrated on only one side

• Fastenings are not checked after the first few kilometers

Problems often arise not from gross negligence, but from small oversights.

Aerodynamics also play a role

In addition to weight, the shape of the load also influences the vehicle's behavior. Large roof boxes or bulky items can significantly increase air resistance.

This can affect:

• Driving stability in crosswinds

• Noise development

• Fuel consumption

• Stress on the roof racks

Good positioning of the load and stable fastening help to reduce these effects.

Practical tips before every journey

Before longer journeys, it is advisable to briefly check the entire roof structure:

• Are the crossbars firmly seated?

• Is the roof box correctly mounted?

• Are the lashing straps tightened?

• Is the weight evenly distributed?

• Is there any play or movement in the structure?

After the first few kilometers, the load should be checked again.