In just a few years, the roof box has become the travel companion of many families looking for cargo space. As with any load secured to the roof, care must be taken to ensure that the safety of road users is not jeopardized. What are the rules to respect with a roof box? Our answers.
Is there a specific regulation for roof boxes?
There are no regulations specifically dedicated to the roof box, but there are more general regulations on the loading of a vehicle.
It appears in articles R312-19 and following of the Highway Traffic Act:
- The driver is responsible for securing the load to his vehicle. Every precaution must be taken to ensure that the loading of a vehicle is not the cause of damage or danger (article R312-19).
- At the rear of a vehicle or trailer, a load may not exceed more than 3 metres (section R312-21).
- At the front, a load on the roof must not exceed the end of the hood of the car (article R312-22).
- In any case, it is absolutely forbidden to exceed the GVW (total permissible laden weight) which is indicated by the manufacturer of the car (article R312-12).
Good to know: for exceeding the load, the roof box is only slightly concerned. It rarely protrudes from a vehicle because its volume is chosen according to the needs of the users (just like the size of the car). There are indeed roof boxes of all volumes and lengths, and it is widely recommended not to opt for a model that exceeds the contours of the vehicle. Always choose a roof box that meets NF standards.
Our advice
When the car is more loaded than usual, it is advisable to slightly overinflate the tires to compensate for overweight.
Read alsoAuto: is the contents of your trunk insured?
What is the speed to respect if you drive with a roof box?
The Highway Code does not provide for a specific speed to be respected with a roof box. With or without a trunk on the roof, a car only has to respect the speed limits established on each road or highway.
However, it is advisable to adapt your speed when a trunk is mounted on the roof because:
- Any load on the roof may be subject to tearing. A risk that increases with the increase in speed, and especially when overtaking a truck, because the passage can create a depression effect.
- It can change the stability of the vehicle, especially when there is wind or harsh weather conditions (and even more so for a very light vehicle). Adapt your speed according to the circumstances.
Take all necessary precautions to ensure your safety on the road and that of others, but be aware that you will not be fined driving at the regulatory speeds with a roof box.
Good to know
Your tires are subject to maximum speed. Check the speed rating of your tires, indicated by a letter in the dimension reference.
Read alsoCan I be ticketed for speeding without radar?
What is the maximum weight to respect with a roof box?
The maximum weight to be respected with a roof box is indicated by the manufacturer, because each model has a different load capacity depending on its volume.
It is therefore essential to respect this maximum load, but also to align it with the vehicle's GVW (and to place the belongings intelligently in the roof box in order to distribute the weight fairly).
If your roof box is capable of supporting 75 kg of cargo, but the total permissible laden weight of the car is already reached by the luggage and other belongings placed in the trunk, you will not be able to put anything extra in your roof box.
Attention, in the maximum load indicated by the manufacturer, it is necessary to count the weight of the roof box itself, empty.
Note that if you exceed your GVW, or if you load your roof box beyond the manufacturer's recommendations, your car insurance may decide not to compensate you in the event of an accident (whether rightly or wrongly).
Good to know
The roof racks that support your roof box also have a maximum laden weight that must not be exceeded. Be sure to equip yourself with roof racks whose authorized weight is consistent with that of the roof box.
Read alsoHolidays: understanding parking PVs
Why do you need to store your roof box when you arrive at your destination?
It is advisable not to leave the roof box on the car when it is not in use, either after arriving at your vacation spot, or simply when you return home.
Storing your roof box allows you to:
- Avoid over-fuel consumption: A roof box can generate fuel consumption up to 15% higher than normal consumption. A disadvantage that can be accepted when it is useful, but not when it is empty.
- To preserve your roof box from external climatic conditions, because even if it resists very well to bad weather, a permanent outdoor life will create premature wear (so to store indoors, or under an airtight tarpaulin).
- To be able to access all car parks: some parking areas have restriction bars in height generally placed at 1.90 m. With a roof box, it may be impossible to cross these bars if your vehicle is already high.
Our advice
Choose a roof box with an opening on each side, to cope with all parking configurations.
Read alsoDriving in flip-flops: is it prohibited?
What alternative to roof boxes?
If the idea of putting a trunk on your roof does not appeal to you, know that there is the trunk on a hitch ball.
As its name suggests, it comes to take place on the hitch ball, just like a trailer or a bike carrier.
It frees your roof, but be careful not to forget it when reversing because some models of small volumes are not seen at the height of the rear window.
Good to know
The trunk on a hitch ball is an excellent solution if you have a convertible with soft top, because a roof box can only be installed on a hardtop.
Read alsoCan we break the window of a car to save a child or an animal?
To remember about the rules to respect with a roof box
Here are the rules and precautions to follow with a roof box:
- The Highway Code does not impose specific driving conditions with a roof box.
- The weight supported by the roof box is indicated by the manufacturer and the GVWR of the vehicle must always be respected.
- Choose roof racks that can support the load of the roof box.
- Do not leave your trunk permanently installed on the roof (preferably indoor storage).
- You can also opt for a trunk on a hitch ball (instead of the roof box, or in addition).