How to Build a Perfect Rooftop Garden

Rooftop Garden

With our cities becoming increasingly more populated and our green spaces significantly reduced, it’s tempting to snatch up any spare space you might have to create an outdoor haven. Maybe that’s why rooftop gardens are growing more popular than ever before.

In inner city locations, more people are turning to apartments and townhouses with little or no backyard. As our properties become smaller, our gardens are shrinking – or being obliterated altogether! It’s a sad sight to see, which is why we’re so happy rooftop gardens are gaining currency across Australia.

Whether you’ve found that perfect inner-city pad or are looking to green up your outback property even more, a rooftop garden is the perfect way to introduce more – or any! – chances for peace and quiet in the outdoors.

Why You Can’t Go Wrong with a Rooftop Garden

Cities, municipalities, and corporations worldwide are endorsing the rooftop garden movement (check out New York’s Rockerfeller Centre rooftop gardens if you don’t believe us). Melbourne already has over 100 rooftop gardens.

roof garden

But really, what’s so great about a bit of green space on top of your building? Plenty! And we’re happy to list just a few of those benefits here:

  • Extra outdoors space
  • Improved air quality
  • Aesthetic value as a decorative piece
  • Added value to property
  • A way to capture and retain storm water
  • Insulation against heat gain or loss (helping you save on electricity and gas bills!)
  • Providing a home to native animal species
  • Prolonging your roof’s waterproof membrane

Types of Rooftop Gardens

However you approach your rooftop garden depends upon the capabilities of the space you’re working with. Depending on your roof’s size and strength, you’ll have to choose between building an extensive or intensive green roof.

Extensive green roofs.

If you haven’t got much space to work with, or if your rooftop doesn’t have the structural support for a fully functional outdoors space, you might want to stick with an extensive green roof.

This type of green roof is lightweight, designed to support a shallow layer of soil and vegetation no more than 20 cm deep.

It’s also great for busier city slickers; extensive green roofs require minimal maintenance, since they accommodate low-growing plants with fewer water needs.

Intensive roof gardens

You can’t deny these roofscapes are beautiful. With the right structural support, you can build yourself a proper backyard on your rooftop, complete with almost anything you could wish for (barbeque, swing, outdoor dining set – even a pool if you’re super lucky).

Intensive roof gardens give you a deeper plot so you can work with a much greater variety of plants and build sophisticated structures. But that also means you’re looking at a garden needing regular watering and a solid irrigation system.

How to Build Your Own Rooftop Garden

Whatever kind of rooftop garden you’re interested in, it’s hard to know where to begin. Rooftop gardening sounds like a complicated business, so we’ve broken it down into easy steps for you.

moss roof

Step 1: Check your local restrictions

Before you even begin planning your rooftop garden design, you need to ensure you can legitimately build one in your neighbourhood. Check if you need council approval and what relevant local ordinances there may be.

If you’re in a rental property or part of a home owner association, familiarise yourself with any regulations you may have to overcome.

Step 2: Evaluate your structure

This is the trickiest of all your DIY garden rooftop steps because you’ll need to enlist the help of a professional. Get an architect or contractor to check the structural capabilities of the roof and to make sure the roof’s existing waterproof membrane is in good condition.

This great interview with an architect on rooftop gardens at Realestate.com.au helps you see what professionals will cover.

Step 3: Decide on Design

Once you’ve figured out the weight-bearing load of your rooftop, you get to the good stuff – DESIGN! This is the part we love most, putting together the intricate details of a rooftop garden to create an amazing whole.

The design stage has plenty of fun components, but it also requires a bit of logistical thinking. How are you going to create your shade? How are you going to counter strong winds? And what kind of barriers will you put up to guarantee your own privacy as well as that of any neighbours your garden may overlook?

Is there any hard infrastructure you may want to install? This could be some form of decking or tailored garden boxes. Or it could be trellises or fences to act as a windbreak and privacy screen. You can even thinking about water features, rockeries, or plenty more.

This is also the time to think about what kind of greenery you want and how you want it to be shaped. Do you want natural or artificial grass? Curved or square garden beds?

And don’t forget theme! Vegetable garden, ornamental, oriental, European…

If you’re looking for inspiration, you’ll find plenty of ideas across the web. We love these 20 wonderful and whacky ideas by The Self Sufficient Living.

flowers on roof

Step 4: Build

Really, the design and build stages come hand-in-hand. Be prepared to rework your design as you build if you come across obstacles or decide something doesn’t work as you expected.

DIY rooftop gardens are possible, but it would probably be easier to contract a professional for the initial construction stages. The roof membrane protects your building’s interior from the elements so you need to be extra careful not to damage it during construction.

There are several design elements you need to implement in your building stage. For a start, your rooftop needs to have a slope of at least two degrees to allow water drainage.

And if you’re planning on planting vegetable and fruit plants, you want to ensure your garden boxes have a minimum soil depth of 30 to 40 centimetres.

In sum, when you design and build your rooftop garden, make sure you consider:

  • Shade
  • Privacy
  • Drainage and irrigation
  • Accessibility of water for plants
  • Your access point
  • Drainage
  • Electricals (lighting, power points, etc)
  • Permanent obstacles (television antennas and other aerials, pipers, solar reflectors).

Garden Therapy offers this wonderful detailed plan to build an edible rooftop garden.

But if you’re better with visuals, check out Senga’s helpful video below:

Step 5: Time to Decorate

If design brings out your inner builder, decorating calls for your creative side. Whereas design is about observation, research, and a bit of maths (sun positions, ground angles, soil depths), décor is about browsing, comparing, contrasting and experimenting.

Whatever garden theme you choose in the end, there are a few permanent truths to guide your décor choices.

  1. Stick to light décor items. Look for lightweight materials. Choose plastic or fibreglass instead of wood for garden furniture and decking or artificial grass instead of concrete or pavers.
  2. Keep furniture, beds, or other objects away from your roof boundary if they can be used as steps or ledges.

Don’t forget to consider which amenities you may want to enjoy atop your high rise garden. A barbeque, seating arrangements (we love these pieces), shade umbrellas, storage boxes – maybe even a clothes line could be useful up top.

And no, we certainly haven’t forgotten about the plants. Your plants are the most important showpieces of your rooftop garden, the whole reason you went through all this work in the first place. They offer the fresh air, the visual beauty, the home-grown veggies. Here are two important tips to picking rooftop garden plants:

  1. Choose hardy plants that need little water: succulents work well.
  2. Plant just about any vegetable and herb plants – as long as they aren’t root veggies. Most vegetable plants need only about 20cm of soil.

Additional Support

Australian authorities are vigorously supportive of rooftop gardens, which means they supply plenty of quality resources to help you grow a successful green roof. Check out the following:

Mega Guide To Australian Native Plants: We may be a little biased but this guide is a great way to learn more about Australian natives which just may end up on your rooftop garden.

Green Roofs & Walls: Your Inspirational Guide: This is a great guide by Green Villages and supported by the City of Sydney. It covers motivations, instructions, and inspiration for creating a rooftop garden. Especially valuable is the section on the best plants for an Aussie rooftop garden.

Green Roofs and Walls Facts: This City of Sydney document outlines design features to consider and tips to help with your development application.

Your Home: This Australian Government resource goes into greater detailed about intensive and extensive rooftop gardens.

Growing Green Guide: A Guide to Green Roofs, Walls and Facades in Melbourne and Victoria, Australia: This downloadable guide is packed full all sorts of green roof information, from its advantages to technical advice and case studies.

Ready to Renovate?

At Australian Outdoor Living we offer a range of products and resources to help you improve your garden – whether it’s a backyard OR a rooftop! Check out some of our other resources below:

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About Alex Kuchel

This is Alex. Alex is the National Brand Manager at Australian Outdoor Living (AOL). By day, she’s a member of AOL’s marketing team. She helps to conjure up ideas on how best to promote Australian Outdoor Living and enjoys working with a pretty awesome team of clever cookies. By night (and weekends), she enjoys the company of her family and friends. She’s a big believer in sun shine and does her best to enjoy it with those she loves most.”