Roof Box Buying Guide

A car roof box is a cargo storage container designed to be mounted on the roof of a vehicle, providing additional space for transporting various items. A car roof box expands your vehicle's storage capacity, allowing you to carry more items comfortably. It keeps your interior clutter-free, ensures passenger comfort, and offers an ideal solution for long journeys or outdoor activities.

No, not every roof box is compatible with every vehicle. Most roof boxes require a set of roof bars or a roof rack system to be fitted first, and your vehicle must be able to support them. It's also important to check that the roof box is compatible with your roof bars and that the combined weight of the box and its contents does not exceed your vehicle's maximum roof load.

If you're unsure, use our vehicle registration lookup to find compatible roof bars before choosing a roof box.

When choosing a car roof box, consider the following factors:

▶ Capacity: choose a size that suits what you plan to carry, whether it's luggage, camping equipment, skis or pushchairs.
▶ Compatibility: check that the roof box is compatible with your roof bars and your vehicle's maximum roof load.
▶ Fixing system: most modern roof boxes use quick-fit mounting systems that install in minutes and fit roof bars up to around 80mm wide.
▶ Aerodynamics: a streamlined design helps reduce wind noise and minimise the impact on fuel economy.
▶ Security: look for central locking systems that secure the lid at multiple points and help protect your belongings.
▶ Material quality: durable, UV-resistant materials will better withstand the weather and regular use.
▶ Opening side: some roof boxes open from one side, while premium models offer dual-side opening for easier loading and unloading.

The first thing to consider is how the roof box will attach to your vehicle. If you don't already have roof bars, you'll need to choose a set that's compatible with your vehicle first.

Once your roof bars are installed, most modern roof boxes will fit without issue thanks to universal quick-fit mounting systems that fit around roof bars up to 80mm wide, meaning they should fit almost any set of roof bars on the market. However, it's always worth checking the manufacturer's compatibility information before purchasing. You don't need to match roof bar and roof box brands either as most leading brands are designed to work across a wide range of roof bars, provided they meet the required dimensions.

Weight limitations vary depending on the model and your vehicle's roof rack capacity. Roof boxes will have a volume figure displayed, with most somewhere between 350-550 litres but some going up beyond 600 litres! However, it can be hard to imagine the size of the box based on the volume figure alone, so it's best to check the exact measurements too. Boxes will also have a load capacity listed, usually between 50-100kg.

It can be tempting to cram as much into the box as possible, but the car itself will have a load limit and it's vitally important to not overload the roof. Remember to count the weight of the roof box as part of the overall load too! When loading the box, it's best to keep an even weight distribution and heavier objects at the bottom and middle of the box. Car straps can be used to keep items in place and secure during the journey. Check the specifications provided by the manufacturer to determine the maximum weight the roof box can safely carry.

When selecting a roof box, the shape and size play a crucial role, requiring an understanding of your potential future cargo. While it might be tempting to opt for the largest box available, it's important to note that small cars may not be compatible with very large roof boxes. Conversely, if you anticipate transporting long or bulky items, a small roof box may not be the optimal choice. Thankfully, a wide range of options exists, ensuring that there is a suitable box to meet everyone's needs. Narrow roof boxes prove particularly beneficial if you intend to carry additional items on the roof bars, such as kayak racks or cycle carriers. Additionally, it's worth considering the height of the box, considering both the accommodation of bulky items and factors like aerodynamics and fuel efficiency.

Installation procedures may vary, but typically, you will need to secure the roof box to the roof rack using t-track adaptors that attach to the bottom of your roof box and slide through the middle of your fixed roof rack systems or by using u-clamps that attach to the roof box and wrap around the roof bars in a loop. Refer to the manufacturer's instructions for specific guidelines.

Yes, most car roof boxes are designed with dual side opening systems, allowing convenient access to your stored items without removing the entire box. Basic boxes will likely have a single-side opening, or perhaps even a rear opening. Whilst this works as a way of loading and unloading items into the box, a rear opening may not be suitable for a long vehicle and is best suited to small hatchbacks.

A dual-side opening box offers the best solution and is especially useful for travelling abroad, as you can access the contents from either side of the car. If you can reach your vehicle roof to lift the lid up then access should not be a problem, otherwise a handy stool or perching on your car door trim may provide an added boost.

The maximum recommended speed when driving with a roof box is typically 70 mph, although you should always follow the lower of the roof box manufacturer's limit, the roof bar manufacturer's guidance, and the legal speed limit where you're driving.

Driving at high speeds can increase wind resistance, reduce stability, and place additional strain on your roof bars and roof box. If you're travelling in strong crosswinds, heavy rain or carrying a fully loaded roof box, reducing your speed further is recommended for a safer and more comfortable journey.

Yes, fitting a roof box will usually increase fuel consumption because it creates additional aerodynamic drag. The impact varies depending on the size and shape of the roof box, your vehicle and how fast you drive.

Modern aerodynamic roof boxes are designed to minimise drag, but you'll still achieve the best fuel economy by removing your roof box when it's not in use. Packing efficiently and avoiding unnecessary weight will also help improve efficiency.

Some roof boxes can produce wind noise, particularly at motorway speeds (although the noise is normally considered to come from the gaps between the roof bars and your vehicle roof), but modern aerodynamic designs significantly reduce this effect.

The amount of noise depends on the shape of the roof box, the design of your roof bars and how the roof box and roof bars are positioned. Premium roof bars with aerodynamic profiles can also help reduce wind noise. If you notice excessive whistling, check your roof rack setup (are they the right way around for instance?) that the roof box is mounted correctly and all fittings are tightened securely.

Most car roof boxes come with built-in locks to deter theft. Ensure that the model you choose has robust locking mechanisms for enhanced security. A double centralised locking system which comes with keys tends to be the best solution for most users on the road.

It is generally recommended to detach the roof box when not in use to reduce wind resistance and potential damage. Although modern roof boxes are designed with aerodynamics in mind, they will all negatively impact the fuel economy so it’s best to remove the box when it’s not required. However, some models may be suitable for extended periods of use. Refer to the manufacturer's guidelines for specific recommendations.

A correctly fitted roof box should not damage your vehicle. However, problems can occur if the roof box or roof bars are installed incorrectly, overloaded or not compatible with your vehicle (e.g. you don't want any overhang over the front or rear windows).

Always ensure your roof bars are the correct fit for your vehicle, follow the manufacturer's installation instructions and never exceed your vehicle's maximum roof load. It's also worth checking that the roof box is securely fastened before every journey you take.

Most roof boxes are made from ABS plastic, which is light, impact-resistant, and great for handling and installing on your car. It’s also moulded into smooth, aerodynamic shapes that boost fuel efficiency and cut down on wind noise. When it comes to finishes, you've got three main options: gloss, matte, or textured. Gloss looks shiny and protects against UV rays and fading, while matte gives a more understated, glare-free look. Textured finishes add grip and do a good job of hiding scratches. Ultimately, pick the coating that fits your style, durability needs, ease of maintenance, and how it matches your car.

While the colour or material of a roof box may not be essential, it can still be a factor worth considering. Typically, most boxes come in a sleek gloss black finish, which tends to complement almost any car on the road. However, for those seeking a touch of uniqueness, alternative options are available. Shades such as grey, silver, or white offer a subtle departure from the traditional black, providing a sophisticated and versatile look. Ultimately, while the colour may not impact the functionality of the roof box, it can enhance the overall aesthetics and reflect the owner's personal taste.

Regularly clean the roof box with mild soap and water and avoid using abrasive materials. Inspect the box for any signs of damage or wear and ensure that the mounting hardware is secure. Most boxes will take up quite a bit of room and there are some storage solutions available, such as racks and pulley systems. If those solutions aren’t possible, a roof box lid cover can be a simple way to protect the box from any dirt or damage when it’s not on the car.

There are primarily two types of car roof boxes: hard-shell roof boxes and soft-shell roof bags. Hard-shell boxes are durable, weather-resistant, and provide better security, while soft-shell bags are lightweight, flexible, and easier to store.

In some cases, it may be possible to install multiple roof boxes if your vehicle and roof rack can accommodate the additional weight and dimensions. Consult the manufacturer's guidelines for compatibility and safety information.