Roof boxes were initially invented for transport of skiing equipment in a compact car. Over the last 25 years it has become a frequently used accessory especially in the winter season. Installation errors and faulty loading of roof boxes have caused several accidents. Read in this article what to observe when using a roof box.
The roof boxes for large items
For a long period of time, the trailer was the only option for enhancing the loading capacity of a car. It has plenty of disadvantages: the driving dynamics of the car change considerably, and manoeuvring, particularly backing up becomes considerably more difficult. And what is more: since 10 years, driving with a trailer requires a separate driver’s licence.
The roof box was invented to facilitate transport of light but bulky items in standard family cars. Initially this need existed mainly for skiing equipment. Even in station cars, transporting long skis and the vulnerable skiing sticks to the holiday destination undamaged in a fully loaded car posed a problem. Nowadays, roof boxes have become very popular for transport of long objects.
Another target group for this product are camera men and photographers. Camera tripods, lighting equipment and backcloths can very conveniently be transported in the roof box. It is however important to stick to certain rules when loading roof boxes. Otherwise, driving with a roof box becomes uneconomic or even dangerous. Read everything in this companion what you need to know about installing and loading a roof box.
Construction of a roof box
A roof box is an aerodynamically optimised plastic box. This material has become standard for roof boxes because it is light, cheap and water-proof. Roof boxes have a shell structure. The upper shell envelops the bottom half, making it waterproof even at high speed.
It has sturdy hinges on one side, and a reliable locking mechanism on the opposite side, preventing the roof box from opening during driving. The roof box is fixed to the roof rack with special brackets. It is essential for the roof rack to match the car.
In the past, traditional roof racks were fixed to the rain gully of the car roof. These are definitely unsuitable for roof boxes. The upward air stream caused by the roof box is too strong for a universal roof rack. A fitting roof rack is fixed on the provided fixing points in the roof support and reliably anchored there. This solution enables the safe mounting of a roof box.
The correct installation for safe and fuel-efficient driving
Two things are important for the installation of a roof box: the accessories must be complete and free of damage. If a roof box or its brackets already show cracks, the system can no longer be used. The load will cause a crack to widen, ultimately causing the box to fall off, resulting in a dangerous road situation for yourself and other traffic participants. And even if this would only cause material damage: a substantial fine for negligent use of a damaged roof box cannot be avoided.
The roof box is fixed to the roof rack in accordance with the manufacturer’s specifications. Many manufacturers even prescribe the screw torque and this should be observed. Not every roof box fits on every car. Good advice and preliminary research are therefore essential.
For reasons of fuel-efficiency it is important for the box to be mounted straight onto the roof rack. A crooked roof box increases the air resistance of the car. Approximately 20% increase of fuel consumption is to be reckoned with anyway. By mounting a roof box correctly, this value is not unnecessarily exceeded.
Prior to installation of the roof box, hinges and locks should be inspected. These tend to stretch on cheap products. The wind forces pulling at the roof box are stronger than imagined. Therefore: check the hinges if they allow both halves to fit and the lock on reliable functioning prior to installation.
A roof box should must be lockable. Otherwise it would be an easy target for thieves. Branded manufacturers equip their products with high-quality locks, contrary to cheap products.
With all the correct installation and choice of high quality parts, additional securing the box with two lashing straps can do no harm. Lashing straps with an integrated ratchet are particularly suitable. Please note: these belts resist high tension. In case of a plastic box it is easy to exaggerate. A lashing belt should not be pulled tight to its extreme. Adjusting it by hand, ensuring the box doesn’t shift is enough. The remaining piece of the strap should be stowed, preventing it from loosening and flying in the wind.
Substantial price differences
Comparing roof boxes will show prices diverge greatly. Prices from branded manufacturers like Thule or Kamei are often the triple amount of those from unknown manufacturers. A cheaper product is less durable, and with respect to installation convenience and safety it cannot compete with products from a high-grade supplier. Boxes opening during driving, instability of hinges and locks or products getting jammed, which can only be opened by force are no exception for roof boxes under 150 euro (± £ 135). A branded product often costs more than 500 euro (± £440). Better quality is evident: sturdy material, adequate locks and hinges and a safe installation system turn a quality branded roof box into a long-term investment. Once purchased, you only need to worry about efficient loading.
Safe and proper loading
A roof box is only suitable for light items, its position, rather than its stability making it unsuitable for heavy items. The heavier the load of a roof box, the higher the car’s centre of gravity. Sooner or later you would feel the weight pulling on the car in every curve. Apart from the inconvenience this could be dangerous. Therefore: only put items in a roof box which don’t fit in the boot. Long, big and light items are ideal for roof boxes. Other items can be stowed in it as well as long as they are not too heavy, like. e.g.:
Less suitable are:
The rule of thumb is: everything light and long fits in roof boxes, all heavy items go in the boot.It is important that transported luggage in the roof box cannot move. Rolling objects could break, damage the roof box or even open it. Therefore: always stow the roof box up to capacity so that everything remains in its place. Pillows, blankets and kitchen paper rolls are excellent buffers.
Include own weight and volume
Not only are branded products more stable than cheap roof boxes, but also lighter. This is particularly important for loading. The load of a roof box should not exceed 50 kg and therefore 5 kg make a 10 % difference. Less goes a long way and this applies to volume as well. Most car boxes have a 320 – 380 litre capacity. Several manufacturers advertise loading capacities over 500 litres. These volumes are generally at the expense of aerodynamics with a higher fuel consumption as a result. The roof box therefore should always match the actual need. Only then, driving with added loading capacity remains economically feasible.
Foto: Nickolya, ilterriorm, meesilpa sornsing, Bennian, BK foto, supot phanna, RedKoala, alexfan32, Kostsov / shutterstock.com