Vehicles are designed to carry both passengers and cargo.
But what if your cargo is too big for the trunk or passenger compartment?
Storing cargo on the roof may seem like the logical choice, but you have to worry about more than your cargo flying away.
How Much Weight Can A Car Roof Support?
Typically, the roof of the car is not supposed to be a load-bearing surface. Most vehicles shouldn’t have more than 50 pounds away strapped down to the roof at any time, or else the metal cut the form and dent. Some vehicles, like cargo vans, can I have hundreds of pounds of weight on the roof, provided it’s spread evenly.
There are, however, it’s several potential modifications that allow cars to carry more weight on the roof.
The most popular is a roof rack, which distributes the load across several secure points and elevates the cargo off the surface of the roof.
In this article, we’ll cover roof racks, along with roof materials, clamshell boxes, and more.
We sourced the information used in this article from roof rack specification guides and from years of experience in the automotive world.
Is it Safe to Stand on a Car Roof?
Not unless you want to leave a couple of foot-shaped dents.
It’s generally not safe to stand on the roof of the car.
And the metal that makes up the body panels, especially large, single-piece body panels, is rarely thick enough to support the weight of a person when concentrated on a single point.
Granted, there are some exceptions to this rule.
Some vehicles with fiberglass tops can withstand extra weight, as can cargo vans and other utility vehicles.
However, there are plenty of videos online of people ruining cars by standing or jumping on them.
Remember that if the surface isn’t designed to support weight, you probably shouldn’t stand on it.
Can You Strap Objects to a Car Roof?
In some cases, it’s totally acceptable to strap items to the roof of the car.
However, it depends on the car, the loaded question, and the shape of the roof.
For example, there’s hardly any safe way to strap a couple hundred pounds of two by fours to the roof of a Toyota Corolla.
That said, an aftermarket roof rack might solve the problem.
How to Tell How Strong Your Car Roof Is
Before subjecting the roof of your car to excessive loads, you can reduce roughly how much weight the roof will support with a few clues.
These include the material, the type of vehicle, and the shape of the roof. Simply pressing down on it with your hand may be enough.
Car Roof Materials
Automakers have used at least half a dozen different roof materials over the year, and sometimes a combination of more than one.
These materials have different strengths, and some can support loads better than others.
Here are several common car roof materials and the loads they can support.
Steel Car Roofs
The most common car roof material is steel.
Steel is also the strongest in most useful for carrying cargo or mounting accessories.
The vast majority of cars from all eras have steel roofs, except for convertibles.
Despite its strength, the steel roof material on a car is typically quite thin.
That means it can be easily dented if weight is applied incorrectly.
Aluminum Car Roofs
Some newer vehicles, like the Ford F150, have aluminum roofs.
Aluminum roofs, though technically stronger than steel by weight, hardly ever weigh more.
That means that they’re easier to damage than steel roofs, and they’re also considerably more expensive to repair.
Aluminum doesn’t have the elasticity of steel, so it’s a lot less likely to bounce back if depressed by a heavy load.
Other problems, such as warping and cracking, are more likely to occur with aluminum.
It’s best not to subject an aluminum roof to excessive weight under any circumstances.
Many vehicles produced from the 1970s to the early 2000s came with vinyl hardtops.
Though these vehicles appear to be convertibles, they’re actually steel roof cars with a vinyl cover on top.
In many cases, cars with the final tops had manufacturing defects in the roof, which the vinyl covers.
A vinyl hardtop vehicle has a roof that doesn’t move.
And despite potential defects that caused it to be chosen for covering, the roof it’s just as strong as a comparable model in most cases.
It can be treated like a steel roof, provided the vinyl doesn’t tear.
It may be even more forgiving than a traditional steel roof, as dents won’t be as readily apparent.
Convertible roofs are usually made of thick flexible vinyl supported by steel or aluminum rods.
A convertible should never be used to carry cargo on the roof.
There’s virtually no structural support, even on modern convertibles with reinforcement.
The frame structure that holds up the roof is designed to bear loads consistent with wind forces and the roof material itself; nothing else.
Adding weight can deform the frame and ruin the seals of the roof.
Removable Hard Tops
Some removable hardtops are stronger than others.
Fiberglass hardtops are quite versatile and can support more weight than other kinds.
Modern fiberglass hardtops, like those found on the Jeep Wrangler, are designed to support a certain amount of weight.
Individuals often mount roof racks and even pop up campers on these hardtops.
Use caution when securing your load, as the slick surface makes it easy to slide off.
Also, don’t load a fiberglass hardtop to the point where it begins to flex.
Glass Roofs and Sunroofs
Many sedans are equipped with glass sunroofs or moonroofs.
These glass openings represent a considerable weak spot on the roof of the car
They should never, under any circumstances, be subjected to load.
Even if they don’t break immediately, hitting a bump or shifting the weight could cause the glass to implode on the driver and passengers. Even safety glass has its weaknesses.
Are Old Car Roofs Stronger?
In many cases, older cars used thicker and more rigid steel on the roofs.
There are a number of reasons for this, chiefly due to the lower cost of materials and less precise manufacturing techniques.
American cars, in particular, had very strong roofs for much of the 20th century.
In most cases, it’s safer and easier to carry cargo on these vehicles, both due to the shape and composition of the structure.
Are SUV Roofs Stronger?
Generally speaking, SUV roofs are stronger and more suitable for carrying cargo van passenger car roofs.
The larger the SUV, the more likely this is to be the case.
For example, a Chevrolet Suburban has an enormous amount of flat, strengthened surface area to carry cargo. And many people do.
These vehicles are suitable for carrying much heavier loads than the average passenger car or station wagon.
The same cannot be said for crossovers.
A crossover is essentially a passenger car with a higher profile and occasionally all-wheel-drive.
Traditional full-size SUVs are passenger-carrying bodies mounted to pick up truck frames.
As a result, they’re essentially pickup trucks. Cross overs are almost invariably unibody, and they feature smaller engines and less sturdy construction.
How to Transport Objects on a Car Roof
If you’re set on carrying cargo on the roof of your vehicle, there are several safe ways to go about it.
Depending on the type of vehicle you have, you may have several sturdy and aesthetically pleasing cargo-carrying options available.
Here are a few examples.
Car Roof Racks
Roof racks are extremely common on SUVs and some cars.
A roof rack is essentially a reinforced set of rails or a shallow box that is designed specifically for carrying cargo.
Full-size vans very often have roof racks, which are used to carry everything from ladders to generators.
SUVs are known to come from the factory with a roof rack, or at least an accessory rail for carrying cargo like surfboards and skis.
Iconic vehicles like the Volkswagen Beetle were often equipped with a luggage rack, which pulled it in 4 to 6 places to the roof and carried 50 pounds or more of baggage with ease.
A roof rack isn’t always necessary for carrying cargo on the roof.
But with or without a roof rack, you’ll need to ensure that your cargo is properly secured.
Tie Down Straps
Never transport a load on the roof of a car without tying it down.
It will fall off if you don’t. Tie-down straps are a wonderful way to secure a load, and depending on how much you care about the car, there are several ways to use them.
If your vehicle has mounting points, you can use tie-down straps to secure the top, front, and back of the load.
It’s essential to put force downward force along with front-back and side-to-side force on the load.
Storage boxes first appeared in the 1980s and gained popularity through the 90s and 2000s.
Virtually everybody has seen a Subaru outback with one of those long, clamshell-shaped boxes on the roof.
Clamshell boxes can carry 50 or more pounds and include a lock and a cover that prevents the load from being stolen or misplaced.
A clamshell roof box is an excellent choice for cars, crossovers, and SUVs that need waterproof and secure storage.
Can My Car Use a Roof Rack?
Almost every car and SUV can use a roof rack.
Additionally, purpose-built roof racks are available for almost every late model vehicle.
A notable exception is convertibles, which have no roof rack options for obvious reasons.
If you can’t find a purpose-built roof rack, a metal shop should be happy to fabricate one for you, provided you don’t mind them drilling into the roof of your car.
Most roof racks will require some modification to install unless the hardware and mounting points are available from the factory.