How To Build a Carport

A Quick Guide to Building a Carport

Many people see the benefit of buying a carport to protect their vehicles. But one of the main questions they then have is how to build a carport. You can make and build your own carport from scratch using stock length materials of the shelf, or you can buy a carport kit. A carport kit is by far the better option because apart from saving you time and money, it simplifies the steps in building. We also supply construction and installation guides with all our carport kits, making the process even easier.

But for the purpose of this article, let’s have a quick look at how to build a carport.

When you look at the basic steps of how to build a carport is essentially the same for all the different roof types and designs, it’s just the amount of time and effort that changes.

  • Step 1 – Install the Posts
  • Step 2 – Bolt the Frame to the Posts
  • Step 3 – Screw the Roof Sheets to the Frame
  • Step 4 – Screw and Fix the Guttering and Flashings to the Frame and Roof

Let’s now go into some more detail on this.

STEP 1.  Installing the posts

– There are 2 options to installing carport posts:

[one_half_first]Concreting them directly into the ground[/one_half_first][one_half_last]Fixing them with footing plates onto existing concrete[/one_half_last]

Steel Post Concreted Directly Into Ground

Steel Post Onto Footing Plate






Concreting the posts into the ground is the preferred method and has several advantages. One is that you get a stronger structure overall because of the increased bracing achieved. In simple terms it will move less in windy conditions. Secondly, it looks better as you don’t have footing plates and sometime angle braces in the way. It’s also more practical as you don’t have footing plates to get in the way of anything, or kick your toe on!

The main reason people want to use footing plates is because they already have existing concrete to bolt onto. This can potentially speed up the installation. However, in most cases, there is not enough concrete to fix to. A typical concrete driveway that is 100mm thick is not enough to anchor a carport to. You need proper footings under each column.

Marking out the Post Hole Locations

– Once you know the post location (yes it is different to the carport size), simply start at one corner and work off there. Whether it is 4 posts, 6 posts or more, you will need to ‘check the square’ of the holes. This means making sure that all posts are in the correct spot in relation to the the posts. There are 2 common methods and we suggest that you use both to double check your measurements.

Squaring Diagonals on CarportsMeasure the diagonal measurement between the outside posts. The 2 measurements must be the same. Look at the example drawing below. This is typical post hole layout for a square carport that is 6m wide and 6m long. Notice that the diagonal measurements are exactly the same. This same principle applies for a rectangular carport as well (see 2nd drawing).


3 4 5 Rule For Squaring a Carport Corner

You can also use the ‘3,4,5’ rule. Start in a corner of the carport. Your measure one way in a multiple of 3 (eg.3 metres) and mark the spot. You then come off the same corner and measure in a multiple of 4 (eg. 4 metres) and mark the spot. Then measure across the 2 spots you have marked. If the corner you started with is at 90 degrees, this measurement will be a multiple of 5 (eg. 5 metres). You can then simply the measurements of the sides out to the dimensions of the other post hole locations.

By using these 2 methods, you can ensure that your carport will be at 90 degrees in the corners and will be square.

You’re now ready to concrete the posts into the ground. Follow the instruction in your guide. You can also contact us with any questions you may have.

See the article on ways to install posts into the ground for more information.


Steel Post to Carport Frame

STEP 2. Bolt the frame to the posts

With decent quality carport kits, you should find that the main frame simply bolts together with no cutting or drilling needed. Start by bolting the main perimeter or fascia beams to the posts. Then connect the rafters or purlins to the beams with the supplied brackets. In the case of the gable, hip and dutch gable carports, you will now need to screw the purlins to the rafters, ready to take the roof sheets.


Installing Roof SheetsSTEP 3. Screw the Roof Sheets to the Frame

Now simply use the supplied roof screws to fix the roof sheets to the purlins. Care must be taken  to start in the right place. You don’t simply start at one end for every carport. Follow the instructions in your installation guide so that you get the correct sheet layout.

One other note: In the case of a gable, hip roof or dutch gable carport, you may find it easier to fix the fascia flashings to the carport before the roof sheets go on. This is because they sit under the bottom edge of the roof sheets.


Carport Guttering & FlashingsSTEP 4. ­– Screw and Fix the Guttering, Downpipe and Flashings to the Frame and Roof

This involves fixing off of the guttering, as well as various flashing which may include the ridge capping, barge capping, hip flashings and infill flashings. As mentioned above, the fascia flashing are better to be done earlier.

If your fascia flashings are on then do the guttering. After this you can look at fitting the barge cappings and ridge capping.


Clean Up

A couple of things we suggest to do also. Make sure that there are no metal shavings or what is called ‘swarf’ on the roof sheets or in the guttering. These are formed when you are screwing the roof sheets and flashings on. Either sweep them of the roof or use a blower tool to blow them off the roof. If you don’t they will rust over time and potentially mark your roof etc.

Then have a complete look over your carport and make sure every bolt, screw and rivet has been put in.

That’s it. Your carport is finished!


We hope this information has been helpful. If you’re still not sure exactly about what’s involved in building a carport or diy carport kit, why not give us a call. We’d also welcome the opportunity to give you a quote on a carport kit to suit your house or property.

Thanks very much.

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