The Green Roof Installation Process: What to Expect from Design to Completion

Considering a green roof? That’s a big move, and it comes with a lot of hopes, dreams, and questions.

As for the hopes and dreams, we’re all for them. Green roofs are magical, and we can’t overstate their importance in the climate crisis … and in just making our cities happier places to be.

When it comes to the questions, we’re here for that too. And no question is more common than what to expect from the green roof installation process.

If you’re considering investing in a green roof, then this is the guide for which you’ve been waiting. Let’s consider the step-by-step process of putting one in, from the initial design phase to the final installation. We’ll talk about details of site evaluation, structural assessments, plant selection, irrigation systems, and maintenance. By the time you’re done reading, you’ll have the full view from above.

… much like the birds that will soon visit your green roof. Pretty cool, right?

Getting Started: The Initial Design

Green roof design is an intensive phase that accounts for everything from the local climate to the rooftop you’re working with to your goals for the final result.

Site Evaluation

First things first: Just what are we working with here? Where will the green roof go? How big is the space? What are the types of weather to which it will be subjected? How much rainfall can you expect? How extreme are the temperatures — both hot and cold?

Your green roof professional will want to answer these questions, and more, before they start pitching ideas.

Structural Assessments

You can’t simply throw a green roof on top of a building without understanding what the current rooftop can safely support.

For this, you’re going to need a structural engineer to conduct a thorough assessment and determine the best approach to a green roof. This will largely depend on the age, design, geometry, and load-bearing capacity of the existing structure. It will also take into account:

• Current drainage systems and structural components
• Whether modifications are needed to support the green roof you want
• Building codes and regulations

Answering such questions will help you determine your building options, because you’ll know how much weight the roof can withstand without causing damage. This in turn will factor into the green roof design and the kinds of plants you select.

Plant Selection

Here’s where it gets fun. Once you know what kind of green roof your building can support, you can decide whether you want an extensive or intensive green roof.

Here’s the difference:

• An extensive green roof has a shallower, lighter profile. It uses low-growing plants (think sedum and grasses) to suck up stormwater and keep things cool, but it isn’t a garden in the traditional sense.
• An intensive green roof involves deeper growing media to account for shrubs or even trees. It’s much more garden-like in effect, and it’s often what you’ll find on rooftops geared toward foot traffic and hangouts.

Depending on what your rooftop can support and your end goal, you can choose a palette of native workhorse plants (intensive) or a wider array of species, including exotics (extensive).

Getting Going: The Installation Phase

The green roof construction process is hardcore, man. (Okay, it’s not that hardcore. But there are helmets. Sometimes.)

In essence, a green roof goes in layer by careful layer. These include:

1. Waterproofing membrane: Water is not a building envelope’s best friend, so the first green roof layer that goes on has to make everything leak-proof, redundant, and resilient.
2. Root barrier: Another common avenue to leaks? Plant roots. A root barrier helps to turn plant roots away without doing damage to either building or greenery.
3. Drainage layer: Stuff’s gonna get wet, people. The goal is for the roof to suck up as much water as possible, slowing moisture as it travels through plants and growing media, then finally the drainage layer. However, if things get too wet, that water will need to go somewhere — off the roof.
4. Optional water retention layer: Adding a water retention layer is optional, but if stormwater retention is your goal, then it only makes sense.
5. Filter fabric: As we’ve said, sometimes water has to make its way off the roof, and when it does, we don’t want a lot of soil and nutrients going with it. That’s what the filter fabric is for.
6. Growing medium: Depending on whether your roof is intensive or extensive, and what specifically you’ve got growing on it, this can either take the form of soil or an engineered growing medium that is lighter but has the same/similar properties.
7. Plants: And finally, our beloved plants. Sedum, grasses, flowers, shrubs, trees … we love them all, and they love us.

Seriously, we know. We’ve asked them.

Getting Serious: Following a Maintenance Plan That Works

Once you’ve got your green roof in place, it’s critical to make a plan for stewarding it, because proper maintenance leads to maximum benefits. Regular site visits keep your roof functional and beautiful, and help protect the building as a whole.

Where possible, choose the original designers and installers of your green roof as its caretakers. They are already familiar with its needs and layers, so they’ll do the best job keeping everything in shape.

Getting in Touch: How to Work With Ecogardens

The last thing to get … is in touch. We can’t start until you do.

At Ecogardens, we pride ourselves on offering a one-stop shop for all our clients, whether you desire an intensive green roof hangout or a simple ground-floor pollinator garden. By keeping design, installation, and maintenance under our same small-business umbrella, we guarantee our customers consistent, quality results every time.

Want to put it to the test? Contact us today.