How do I mount a roof box on my car?
10 September 2026
You mount a roof box on your car by placing it on the roof racks and clicking it into place using the box's mounting system. Most modern roof boxes, including all Hapro models, can be mounted without tools thanks to an integrated clamping or rail system. Always ensure that the roof racks are securely on the roof before placing the box. In this article, we answer the most frequently asked questions about mounting, checking, and removing a roof box. roof box on your car.
Which roof racks do I need for a roof box?
For a roof box, you need two parallel roof racks that fit onto the roof rails or the fixed mounting points of your car. Most roof boxes use steel or aluminium crossbars of a standard width, but always check the maximum load and the spacing prescribed by the box manufacturer.
Roof racks come in two types: models that clamp onto roof rails, and models that are attached to fixed anchor points (also known as “fixpoints”) in the car roof. Which type you need depends on your car. Via the online configurator on the Hapro website Quickly check which roof rack is compatible with your specific car model and year. This way, you avoid coming home with a set that doesn't fit.
Also pay attention to your car's maximum roof load. This is stated in the owner's manual and applies to the total weight of roof racks and roof box combined. Always calculate including the contents you are carrying.
How do I attach a roof box step by step?
You attach a roof box by laying it open on the roof racks, positioning the internal clamps or rails on the bars, and then tightening or clicking them into place. The entire process takes less than ten minutes on most models and requires no tools.
Follow these steps for correct assembly:
- Place the trunk open on the roof racks. Open the case completely so that you can access the attachment points on the inside.
- Position the clamps on the roof racks. Slide the clamps or the mounting rail over the beams. Ensure that the case lies straight and is evenly distributed over both supports.
- Tighten the clamps. Tighten each clamp firmly until you feel resistance. With the Hapro Premium-Fit mounting system, you click the clamps into place without tools.
- Close the suitcase and check the lock. Ensure the lock clicks shut properly on both sides.
- Give the suitcase a firm push. Try moving it from front to back and from left to right. If it doesn't move, it is positioned correctly.
Always consult the manual for your specific model. The mounting points and clamps may vary slightly depending on the roof box.
How do I know if the roof box is properly secured?
A properly mounted roof box sits completely still on the roof racks and does not give an inch when you push or pull on it firmly. If you feel a swaying motion, or if the box squeaks or rattles at low speed, the mounting is not tightened enough.
Always recheck that the clamps are still securely fastened after the first five to ten kilometers of driving. Due to road vibrations, clamps may loosen slightly immediately after the first ride. After that, it is advisable to check the fastening every day during a longer trip, especially after driving over bumpy roads or unpaved paths.
An additional point to check: ensure the roof box sits straight on the roof and does not tilt to one side. A crookedly mounted box distributes the weight unevenly across the roof racks, which can strain both driving stability and the racks themselves.
On which side of the roof do I mount the roof box?
Preferably mount the roof box centered on the roof so that the weight is evenly distributed over both roof racks. It is best to position the opening side of the box on the passenger side so that you can safely open the box without standing on the road.
Many families consciously choose to slide the trunk slightly backward on the roof racks so that the view from the windshield remains unobstructed. However, do check whether the trunk still falls within the maximum overhang specified by the manufacturer. Excessive rear overhang can negatively affect driving dynamics and is not permitted in some cases.
Also take into account the height of your car, including the roof box, when driving through parking garages and tunnels. Note the total height before you leave.
Can I take a roof box through a car wash?
No, it is best not to drive through an automatic car wash with a roof box on the roof. The brushes and rotating equipment of a car wash can damage the box, deform the locks, or loosen the mounting. Furthermore, a car with a roof box often does not fit under the maximum height of a car wash.
Do you still want to wash your car? Then remove the roof box first or opt for a hand wash. You can easily clean the box itself with a damp cloth and mild soapy water. Do not use aggressive cleaning agents or a high-pressure washer directly on the locks and hinges, as this can damage the seals.
How do I remove a roof box without damaging the car?
Remove a roof box by loosening or unclipping the clamps on the inside, carefully lifting the box off the roof racks, and placing it on a flat surface. Always do this with two people: a roof box can weigh quite a few kilos, especially if it is not completely empty.
To protect your paintwork, pay attention to the following:
- Lift the suitcase straight up, Do not slide it over the roof or roof racks. Sliding causes scratches.
- Check the roof racks after you have removed the case. Are there rubber seals or protective strips on the bars? Replace them if they are worn, as damaged rubber seals can damage the paintwork.
- Store the suitcase upright or on its side in a dry room. This way, the hinges and locks will remain in good condition longer.
Do you have questions about installation, compatibility, or the right model for your situation? Feel free to contact us — we are happy to help you further.
Frequently Asked Questions
How much weight am I allowed to carry in a roof box?
The maximum load capacity of a roof box depends on two factors: the maximum roof load of your car (found in the owner's manual) and the maximum load the roof box itself can handle. In practice, the maximum load capacity of roof boxes varies between 50 and 75 kg, but your car's maximum roof load is often the limiting factor. Remember that the weight of the roof racks and the box itself also count towards the total roof load.
What do I do if the clamps of my roof box are not properly secured to my roof racks?
If the clamps do not grip properly, first check if the width of your roof racks falls within the specified range of the roof box — most clamps are adjustable but have a minimum and maximum width. Also ensure that the clamps are correctly positioned on the bar and are not located on a rounded or tapered section. If in doubt, consult the manual or contact the manufacturer, as driving with a poorly secured roof box is dangerous for yourself and other road users.
Does a roof box affect my fuel consumption?
Yes, a roof box increases your car's aerodynamic drag, which leads to higher fuel consumption — on average about 10 to 25% extra, depending on driving speed, model, and how full the box is. The effect is greatest at higher speeds on the highway. To limit the extra consumption, you can choose a dynamically shaped model and remove the box when not in use.
Can I also mount my roof box on a leased car or rental car?
For a leased car, it is advisable to consult the lease agreement or the leasing company first, as some contracts impose conditions on the use of roof racks and accessories. With a rental car, in most cases, it is not permitted to mount roof racks or a roof box yourself without permission from the rental company. Always check this in advance to avoid extra costs or liability in the event of damage.
How do I best store my roof box when I am not using it?
Store the roof box in a dry, frost-free area, preferably upright or on its side on a soft surface to prevent deformation. Leave the box slightly ajar or store it open to allow for air circulation and prevent moisture or mold from forming inside. Clean the box thoroughly before storage and lightly lubricate the locks and hinges with silicone spray to keep them smooth and rust-free.
Am I allowed to drive through a parking garage or drive-through with a roof box?
That depends on the total height of your car, including roof racks and roof box. An average roof box adds about 30 to 40 cm to the height of your car, which quickly brings the total height above 2 meters. Many parking garages have a maximum access height of 1.90 to 2.10 meters. Measure the total height of your car with the roof box mounted and make a note of this before you leave, so you don't encounter any unpleasant surprises on the way.
Can a roof box also be used in winter, in snow and ice?
Yes, most roof boxes are suitable for winter use, but there are a few points to keep in mind. Always remove snow and ice from the box before driving, as loose snow clumps on the highway are dangerous for other road users and punishable by law. Also, check the mounting more frequently in winter, as temperature fluctuations can cause materials to expand or contract slightly. Regularly lubricate the locks and hinges with an anti-frost agent to prevent them from freezing shut.