The average car’s capacity for luggage/shopping/junk is 350 litres, which is enough for most people most of the time, and anyone needing to carry more stuff regularly can buy an estate with 500 litres or more.
But rather than buying a huge car an affordable way to add capacity temporarily when needed, for that annual camping trip or when you’ve overdone it at the January sales, is to add a roof box. Specialist roof box company Thule even have one model which has a 630 litre capacity, which is more than an Audi A6 Avant; more in fact than any estate car apart from the Mercedes E-Class Estate.
A top-end large roof box can cost almost £700 plus another £100 for the bars and fittings you’ll need – not cheap, but then you can keep it when you change your car and
First check your car’s owner’s manual to find out more about fitting a roof box and if there is anything peculiar about your vehicle. Also check the car’s maximum roof load so you can make sure you don’t exceed it – roof boxes typically take loads of up to 50kg but your manufacturer may recommend a lower loading.
In order to mount a roof box on your car you need a load carrier (roof bars) for it to sit on and be secured to. The complete load carrier consists of three separately sold components: feet, roof bars and a fitting kit that is uniquely designed for your model of car. Although it complicates the process it does mean if you change your car it is very likely you will only need to replace the fitting kit, saving money in the long run.
Most roof boxes will fit most roof bars but there are cases where the roof bars are too thick for the fittings supplied with the roof box, so do check before buying. The standard seems to be a requirement for bars of less than 80mm in width and between 18 and 35mm in height.
Also you will need to consider the distance between the front and rear bars; larger roof boxes will usually require the roof bars to be further apart to ensure a stable, safe fitting, and so may not fit on smaller cars; ie: a 500-litre roof box on a Mini may not be do-able.
Other considerations when buying a roof box include:
- Total height when fitted to your car – will it fit in your garage or car port?
- Access – check how the roof box opens, some are hinged on one side and it may not be the most convenient side for you depending on where you’ll be loading your car.
- Security – most roof boxes have locks but few are more than token efforts at security. If you’ll have valuable stuff in there, chooses a roof box with decent locks.
- Cold weather capability – if you’re heading to the slopes the extreme cold can make some cheaper roof boxes so brittle they can crack if dropped or handled roughly.
- Fittings – more expensive roof boxes come with quick fit and release systems which make fitting and removing them simpler; important if you’re going to be using it often.
- Width – if you need space for skis or a separate bike carrier, look for a narrow roof box that only takes up only half the width of the car’s roof.
As an alternative to buying a roof box you can hire one locally for about £50 a week, ideal for one-off trips or if you only need one every now and then.