June 18, 2025 Dean Horton

Can I Use Roof Bars and a Roof Box at the Same Time?

Absolutely — roof bars and roof boxes are designed to work together. In fact, a roof box is one of the most popular reasons people buy roof bars in the first place.
But if you’re new to roof storage, you might be wondering: Is it safe? What fits? Do I need to watch for weight limits?

Let’s break it down and make sure your setup is solid, legal, and ready to go.

✅ The Short Answer: Yes, You Can

Roof boxes are mounted directly onto roof bars using either:

U-bolt clamps (wrapped around the bars)
T-track fittings (sliding into the top slot of aluminium bars)

As long as your bars are compatible and weight-rated, you're good to go.

👉 Browse Roof Bar Kits for Your Vehicle
👉 Shop Roof Boxes

🧰 What You’ll Need:

Roof Bars – Fitted to your vehicle
Roof Box – Sized for your needs
Mounting Kit – Usually included with the box
Optional: Rubber mats, straps, or anti-slip pads for added stability

🔐 Most boxes also come with locks built-in, for safe storage on the go.

⚖️ Watch the Weight (Very Important)

Most cars have a roof load limit between 50–100kg, which includes:

Weight of the roof bars (~5kg)
Weight of the roof box (~13–20kg)
Your actual cargo

So, if your car’s limit is 75kg, and your box weighs 15kg, you’ve got 60kg left for your gear.

🔗 Check your limit in: The Legal Load Limits for Roof Bars in the UK

🧠 Pro Tips for a Smooth Setup

Keep heavier items in the boot, lighter gear in the roof box
Pack evenly to avoid rattling or unbalanced weight
Recheck your box mounting bolts every few hundred miles
Use aerodynamic roof bars to reduce wind noise

🔗 See: How to Reduce Wind Noise from Roof Bars

❄️ Seasonal Note: Winter Setup?

Roof boxes are perfect for:

Ski trips
Winter gear
Holiday luggage when boot space is tight

If you’re heading off on a Christmas getaway or outdoor adventure, make sure your roof bars are properly fitted and weight-rated for cold-weather use.

🔗 Need help fitting? How to Fit Roof Bars Like a Pro