How Do You Repair Cracked Rooftop Cargo Boxes?

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Trust me, I’ve been in your position, and it’s heartbreaking. You’ve just invested in your dream cargo box, excellent. However, through either storing, loading, attaching, or transporting, you’ve developed a crack or hole in your box. This almost makes it useless, especially in harsh rainy conditions. Therefore, how do you repair cracked rooftop cargo boxes?

To repair a rooftop cargo box that’s been cracked or has developed a hole is simple. You’ll need minimal DIY skills and the following items: Strong plastic, fiberglass repair (or water weld adhesive), epoxy, liquid rubber, spray paint, painters tape, and newspaper. A combination of these materials can help patch, stick, seal, and restore the beauty of your cargo box. 

Luckily for me and also you, repairing a cracked rooftop cargo box isn’t rocket science. I’m no DIY expert and managed to successfully revitalize my beloved box into a functional storage system again. The above briefly overviews the equipment needed to restore your cargo box. However, it doesn’t go in-depth about the steps taken to achieve this successfully. For a more detailed guide about this, I suggest you become knowledgeable on the below.

Repairing cracks on holes on a rooftop cargo box: a detailed guide 

Above is a small snippet of how to repair your cracked rooftop cargo box. But, reasonably, not everyone has the DIY vision to understand the mentioned details and comprehend the concept of fixing their cracked box. Because of this, we thought we’d mentioned a much more comprehensive guide to ensure you know exactly what to do.

Purchase the right products

The first step of any DIY job is to guarantee you have the right tools for products for the job. To fix a hole or crack on your cargo box, you’ll want to purchase the following goods:

Once you’ve obtained the above, you’re now ready to begin the fixture. Notably, you might want to purchase a small scraper on amazon while undergoing the above.

Prepare for the fixture

If you’re fixing a large hole, you’ll want to grab the strong plastic you purchased and mold it around the broken area. Once you’ve achieved this, you can fix it to your cargo box with epoxy resin. Notably, if you’re only fixing a crack, you won’t need to place a piece of strong plastic over the defective area.

Once you’ve achieved the above, or you’re just fixing a hole, you can start preparing your fiberglass repair. Depending on which brand you choose will highly alter the way you prepare the mixture. Some brands come with pre-made mixtures; others you’ll need to mix yourself. With this, I won’t explain how to mix because it does vary from the supplier. However, whichever fiberglass repair you purchase will undoubtedly come equipped with a how-to manual.

Now you’ve successfully mixed your fiberglass repair, you can apply it to the crack or plastic which you’ve epoxied onto the defective area. Make sure you get an even spread by using a scraper and ensure your covering the entire area. In this type of situation, the more, the better. Lastly, wait for this to dry and proceed with the following steps.

Fill in the cracks or holes

Now the fiberglass repair is dry, it’ll look pretty rough. Therefore, grab some sandpaper and begin sanding down the dried mixture. Don’t worry if it doesn’t perfectly fit with your cargo box, achieving this will almost be impossible.

With your liquid rubber, either spray or paint the defective area. This water seal will waterproof the crack or holes on your cargo box. However, this might not be mandatory if the fiber repair kit has been layered successfully. It’s an additional added layer of security to guarantee that the goods within your box don’t become water damaged during transportation.  

Paint the cargo box

After completing the above, you’re almost finished. Now, you’ll want to place newspaper or painter’s tape around the outside of the crack or hole. This will prepare the location for the painting process, as you might not want your entire box to have a new coating. Once you’ve achieved this, you can start layering the spray or paint onto the box. Notably, you’ll want to apply a few coats to ensure optimal appearance.

Monitor the fixture

Lastly, you’ll want to monitor the fixture. After you’re happy with the result, allow both the paint and other materials to dry, then monitor the completed process. Then, wait a few days and apply pressure to the fixed area to ensure it’s strong. During this time, you could also perform a water test by applying water to the defective area and seeing if it falls through. When you’re pleased that your repair has successfully fixed the crack or hole, you can then start using the cargo box for its primary usage, transporting goods.

How to prevent breaking your rooftop cargo box

Excellent, you’ve now fixed your cargo box. Now, you’ll want to ensure yourself it won’t happen again because it can cause some severe inconveniences. That being said, here are a few prevention methods to reduce the occurrences of breakages on your cargo box.

  • Packing technique – There are some basic fundamental rules you must abide by to decrease the possibility of breakages on your cargo box. If you’re transporting heavy goods and they have the freedom to move around the box during transit, acceleration, braking, or turns might cause your cargo box to become damaged.
  • Unloading method – Additionally, you must remember that most cargo boxes are only created from fiberglass or plastic. Both of these materials are lightweight and aren’t the strongest. Therefore, when unloading your goods, guarantee you’re not bashing around the walls of your box.
  • Storage – Lastly, try to store your cargo box in a sensible area. You’ll want to avoid any other equipment being laid on top of it and away from any potential falling objects.


Without a doubt, repairing a cracked rooftop cargo box isn’t rocket science. But, undoubtedly, it’s not everyone’s cup of tea. Because of this, you might even want to consider renting a cargo carrier for your next adventure. To see if it’s worth it, why not consider reading this blog?

About the author 

Vieira Babeker

Hi! I'm Vieira. I've always been interested in different Auto Accessories

My passion here at is to provide helpful straight forward clear advice and tips for Automotive Accessories.

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