A roof box is an excellent solution for creating additional storage space on your vehicle, making it ideal for family holidays, camping trips, or transporting equipment.
However, we understand that buying a new roof box for your car can be overwhelming, particularly if you’ve never bought one before. You’ll want to make sure you’re choosing the right one for your vehicle and one that suits your storage requirements.
In this handy guide, we’ll take you through all you need to know about a new roof box.
Roof bars and vehicle compatibility
Firstly, if your car doesn’t already have roof bars, you’ll need to get roof bars fitted. You’ll need to assess what type of roof your vehicle has, as this will determine the kind of roof bars, and ultimately the roof box, that will fit correctly and securely.
Understanding your roof type from the start can save you time and money, and help you choose the right setup. There are four main types of car roofs:
Normal roof (also known as a bare roof)
This is a plain roof with no visible mounting points, rails, or fixings. If your car has a normal roof, you'll need roof bars that clamp onto the door frame. These systems usually use a custom fitting kit designed specifically for your car’s make and model.
Fixed points
Fixed point roofs have small, often hidden, mounting points along the roofline, usually covered by plastic caps or trims. These points are specifically designed by the manufacturer for attaching roof bars. They provide a clean look and a secure base for mounting a roof rack system. Once the bars are attached to these fixed points, you can mount your roof box directly onto the bars. These systems come with a custom fitting kit designed specifically for your car’s make and model.
Closed or flush roof rails
Flush rails run along the edges of the car’s roof, but unlike raised rails, they sit flat and close against the bodywork, with no gap between the rail and the roof. They look sleek and modern and are common on newer vehicles. Roof bars for flush rails are designed to grip the rails snugly using custom-shaped rubber feet that match the rail profile. Some cars (like the Vauxhall Zafira) might look like they have flush rails, but actually hide mounting points inside, so it’s worth double-checking!
Open or raised roof rails
Raised rails are easy to spot - they’re the traditional style of roof rail that has a gap between the rail and the roof, forming a loop along each side of the vehicle. This style is super straightforward to work with, especially on SUVs and estate cars. Roof bars usually clamp around the rail using strong rubber grips and pressure, making them one of the quickest and easiest systems to fit. Best of all, many raised rails are compatible with universal bar sets.
Need roof bars?
If you do need roof bars, head on over to our dedicated roof bars page. Find the right roof bars for your vehicle by entering in your vehicle registration or you can book an appointment in-store for our free travel storage consultation.
Book free car travel storage consultation
Understanding mounting systems
Once you’ve chosen the right roof bars, the next key step is understanding how the box attaches to your vehicle. Roof boxes use different mounting systems, and choosing the right one not only ensures a secure fit but also makes the process of fitting and removing the box much easier.
Here are the most common types of mounting systems you’ll come across:
U-bolts
U-bolts fit around the roof bars and are secured inside the box with screw caps. They are one of the most traditional and widely used mounting methods.
The metal brackets wrap around the roof bars from underneath. Once inserted through the base of the roof box, they are secured on the inside using plastic or metal screw caps.
They’re known for their simplicity and reliability, though fitting can take a bit more time compared to newer systems.
Ideal for standard, square roof bars and for those who don’t mind spending a few extra minutes during installation.
Premium fit and master fit:
A more user-friendly option, they feature clamps that tighten around the roof bars using a rotating knob, offering quick and secure installation.
They use specially designed clamps that grip the roof bars securely when tightened with an internal rotating knob or dial.
These systems are often tool-free, which means you won’t need any extra equipment to fit or remove your box.
They offer a more refined look and quicker setup, making them a great option if you plan on taking the box on and off frequently.
Premium fit and master fit is compatible with most roof bars, including aerodynamic or wing-shaped bars.
PowerGrip:
PowerGrip is a modern and efficient mounting system used on many premium roof boxes. It features a pre-installed “claw” mechanism that automatically grips the roof bars when the internal knob is turned. It allows for fast, secure attachment and often in under five minutes.
PowerGrip systems also distribute pressure evenly across the bar, helping to protect both the bars and the box.
Perfect for users looking for speed, convenience, and a professional level fit without the hassle.
Storage requirements
Now it’s time to think about what type of roof box meets your storage requirements. It’s essential to think about what you plan to carry. Roof boxes come in a variety of shapes and sizes, so understanding your storage needs will help you choose a model that suits your lifestyle, without over or underestimating the space you’ll actually use.
Size and Capacity
Roof boxes are typically measured in litres, ranging from compact 250L boxes to large 600L+ models. Here’s a rough guide to what each size can hold:
Small roof box (250–350L):
Ideal for carrying light luggage, camping gear for 1–2 people, or a couple of rucksacks. Great for compact cars or if you just need a bit of extra space.
Medium roof box (350–450L):
A good all-rounder for families or couples. Perfect for short breaks, beach trips, or ski holidays. Can fit several cabin-sized suitcases or large duffel bags.
Large roof box (450–600L+):
Designed for family holidays or long road trips where you need to carry bulky gear like pushchairs, tents, or sports equipment. Best suited for estate cars, SUVs, and 4x4s.
We’ve got a wide range of roof boxes on our website that cater to all storage requirements. From our own trusted Halfords brand to other well-known brands such as Thule, we have something for everyone.
Roof box fitting option
If you’re not confident fitting a roof box yourself, just before adding a roof box to your basket online, there is also the option to add a fitting appointment by one of our experts. This will display a list of local Halfords stores and the option to select available appointments. Simply select an appointment convenient for you and let our experts take care of your roof box fitting.
Remember, you can save money on your roof box and other motoring products when you become a member of the Halfords Motoring Club. Simply click the button below to join!
That concludes the ins and outs of what you need to know when buying a roof box. As mentioned above, you can always book a free in-store appointment with one of our experts if you’d like help in picking the best travel storage solutions for your vehicle.