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Through Bar, Flush Bar or Rail Bar: Types of Roof Racks Explained

You’ll be faced with plenty of choice when deciding what roof racks to get on your car. All roof-rack brands offer multiple bar styles for most vehicles. So to make it easier for you to choose, we’ve put together this guide so you can make an informed choice next time you’re looking at buying a set of roof racks.

The most important factor in deciding what roof racks to put on your vehicle is the fitting requirements of your car. All brands of roof racks offer a vehicle fitment guide which will show you what roof racks will fit your car. This is the best place to start when searching for your roof racks. You can also use the vehicle fitment guide available on Altapac.com. Once you’ve determined what roof racks will work on your car, it’s time to think about what style of roof rack you want. We’ll take you through the pros and cons of the most common styles of roof racks so you can select the roof rack for you.

Through Bars


Easy to mount work and trade equipment, awnings, tents and other 4wd accessories.
Wider bars mean more area to mount things to.
Can be easier to lift items on to the roof rack.
Can be raised or lowered using spacers.

Not as streamlined aesthetically.
Can look out-of-place on smaller cars.

Through bars are the most common style of roof racks we sell. The through bar style sticks out beyond the leg of the roof rack to give you more space to mount equipment to. These bars are ideal for 4wd and camping as they allow you the mount accessories along the full width of the rack and right out to the outermost point of the bar, which is perfect for awnings. They’re very flat too, which means you won’t need extra brackets or mount systems to mount roof-top tents.

Through bars have the added advantage of sitting on the leg rather than have the leg wrap around the bar. This means the accessory channel is always open and available and not restricted by the mounting system. Because of this, through bars can be used with spacers to raise the height of the roof rack to marry up to other bars on the vehicle or on a ute canopy. Because of the exposed channel and the ability to raise and lower the roof bars the through bar is a favourite of tradies and people setting up vehicles for work.

Through bars are ideal for taller cars like 4WD utes and SUVs. Because the through bar sticks out a bit from your roof, you can lift your items up and on instead of lifting up and in and on like alternative rack systems. This means you’re not likely to have to lean across the roof of the vehicle as much, saving your back from stress and saving your car’s paint from your belt buckle.

Flush Bars


Neat and tidy finish.
Carries the same weight as through bars.
Can be mounted on to tracks.

Can be difficult to mount some accessories to.
Have to lean across the roof of the vehicle further to mount items.

Flush bars end at the leg of the roof rack and don’t extend beyond the roof-line of the vehicle. They curve up and in from the sides of the car creating a neat, tidy and streamlined finish. Flush bars are great for smaller vehicles and for carrying items like kayaks, SUP or surfboards, rooftop luggage carriers and other items that don’t require too much width.

Flush bars aren’t the most ideal option for installing awnings, rooftop tents and other items on because they don’t have the width that you need for those items. For awnings, flush bars mean you waste shade area because the awning is mounted further towards the centre of the roof of the car. The other issue with flush bars is that because the feet often overlap the bars, many side mounting brackets for items like recovery tracks, awnings, shovel and jack holders are not able to be used without additional components.

Rail Bars


Very low profile
Neat finish
Easy to install

Limited space under the bar can restrict access for strapping and clamps for items like rooftop luggage boxes.
Not ideal for awnings and side-mounted accessories.

Some cars have raised roof rails, they’re often silver or black and run along the outer edge of the roof of the vehicle. Some rails are flush with no space between the rail and the car’s roof, in this instance, rail bars won’t work. For cars with raised rails, a rail which has space between the rails and the car’s roof, you can use rails bars. On many cars, the rails are mostly there for aesthetics, but you can use them to mount roof racks to.

The rail bar is very neat. We often describe them as being ‘as if your car drove out of the factory with them already on the roof.’ The rail bars are perfect for most leisure applications like bike carriers, water sports carriers and general carrying.

The biggest limitation with rail bars is that their height is determined by the rail and there is no way to adjust the bars higher or lower should the need arise. This means that it can be difficult to mount clamp-mounted accessories like luggage boxes and that reaching under the bar to strap items down can be hindered. Think of rail bars like very flat flush bars in the way the fitting point wraps around the bar. The same limitations that exist with flush rails will exist with rail bars.

Heavy Duty (HD) roof racks.

Most brands offer a range of heavy duty roof racks. Heavy duty bars differ from standard roof racks because of their wider component channel. This allows for a better grip for accessories like conduit carriers, ladder racks and slides. Heavy duty bars are always through bars and have the same characteristics as standard through bars just with the wider channel.

When the time comes to get roof racks for your car, visit our showroom or click here to ask an expert about the best roof racks to suit your needs.



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