How To Build A Rooftop Garden – Step By Step Guide

Introduction on how to build a rooftop garden

Rooftop gardens are not only environmentally-friendly but also a beautiful addition to urban homes. If you live in an apartment or a house with no yard, a rooftop garden can allow you to cultivate ornamental trees, grasses, flowers, and even edible plants. Before you start planting, it is advisable to contact a structural engineer and create a garden plan. Choose appropriate plants and decorations to make the most of the space you have.

In densely populated urban areas, gardeners are often limited by the amount of space they have. If you are running out of room or would like an outdoor living space, creating a rooftop garden could be a viable option for you. Rooftop gardens are a perfect way for urban gardeners to expand their gardening space and make use of frequently unused and wasted space.

how to build a rooftop garden

A step by step guide to build your rooftop garden

Gardening can be an excellent way to unwind and release your mind from daily pressures. Spending time tending to plants under the warm sun can help us to reconnect with the natural world’s splendor, which we have gradually become disconnected from.

If you have access to a rooftop and a landlord who is open to the idea, you can create a rooftop garden at a relatively low cost. It may only cost a few hundred dollars and a weekend or two of your time, or even less if you already have some materials lying around.

This article will provide you with a comprehensive guide on how to create a rooftop garden, including what you need and how to care for it. Additionally, we will outline the numerous benefits of having a rooftop garden, such as increased access to safe outdoor green space, the potential for urban food production, the promotion of individual, community, and cultural diversity, and areas for study and horticultural therapy.

Rooftop gardens also help to improve air quality by absorbing carbon dioxide and providing good sun exposure. Furthermore, they minimize stormwater run-off and can support a rainwater collection system, while providing increased habitat for birds, butterflies, and insects. Rooftop gardens can also reduce heating and cooling costs by providing a layer of insulation on buildings, making use of previously unused or underused space.

step by step guide to build your rooftop garden

Steps about how to build a rooftop garden

These are the steps involved in building a rooftop garden:

Consult an architect

Regardless of how technically, mentally, or physically prepared you may be, having an expert by your side can always be beneficial when building a rooftop garden. There are numerous details to consider when constructing a rooftop garden, and you may not be aware of all of them. Therefore, consulting with a specialist before starting the project is essential. It is necessary to find an architect, not for the actual construction of the garden, but to determine if your home can support the construction of a rooftop garden. The architect’s job will be to assess whether your house is suitable for the creation of a rooftop garden.

Suitability assessment to build your rooftop garden

If you are considering creating a garden on your roof, the first thing you need to do is determine whether your roof is suitable for gardening.

For that, you have to know the answers for some questions below:
  • The structural integrity of your roof
  • The orientation of your roof (e.g., south-facing or shaded)
  • The type of materials needed to protect the roof and provide drainage (e.g., wood decking, pavers, rigid insulation, gravel, or grass)
  • The age and condition of your roof, and whether it will need to be replaced in the near future

Consulting with an architect or structural engineer is crucial in determining whether your home is suitable for a rooftop garden. They can provide you with the necessary structural details to assess whether your roof can support the weight of a garden and what modifications may be necessary to ensure its safety. It is important to note that the architect’s role is to assess the suitability of your roof for a garden, not to actually construct the garden..

Arranging windbreaks to build your rooftop garden

Since rooftop gardens are more exposed to wind than traditional gardens, incorporating windbreaks into the design is important. Solid windbreaks are not very effective and can be easily knocked down by high winds. Instead, trellises or latticed windbreaks are ideal because they can disrupt the flow of wind without stopping it completely. By incorporating trellises or latticed windbreaks into your rooftop garden design, you can help protect your plants from wind damage and create a more enjoyable gardening experience.

Setting up the soil to build a rooftop terrace garden

Preparing the soil for a rooftop garden is an important step and requires careful consideration. To ensure that the plants can grow and stabilize, an adequate amount of soil is required. It is essential to study the depth of soil required for different species of trees, shrubs, and wildflowers so that the right species can be matched with the conditions provided on the roof.

It is recommended to use manufactured soilless media instead of soil or topsoil for rooftop gardening. Soil can be heavy and bulky, and it may also contain pathogen contaminants, potential chemicals, rocks, or debris that may make the product inconsistent. The saturated weight of soil can reach up to 120 lb/ft3 (7.5 kg/m3), which is too high for roof gardening. The ideal saturated weight of rooftop growing media should be 48-65 lb/ft3 (3-4 kg/ m3).

Compost is an essential element in rooftop gardening, and it can be obtained from nearby community gardens or composting operations. While it is possible to make your own compost, it might not be enough for a large rooftop garden. It is recommended not to settle for store-bought compost as it may not be of good quality.

Conduct weight test for your rooftop garden

If your building can support the extra weight that a garden may add, it is essential to pay special attention to the weight of your rooftop garden. Minimizing the weight as much as possible is crucial. For example, using fiberglass or plastic planting containers instead of earthen ones and avoiding the use of pavers is recommended. Additionally, it is best to use lightweight potting soil instead of garden dirt and Styrofoam peanuts for drainage instead of pottery shards.

Choosing the right plants for your roof garden

Gardening on a rooftop presents unique challenges due to extreme microclimates. Sun, wind, and winter survival must be considered when selecting plants. Adequate resources for watering and maintenance must also be available. Suitable plants for a roof garden include Azure bluet, chamomile, sedum hispanicum, Sedum reflexum, thyme, misty butterfly, and blue haze arctic fire. Sensible patching is important to ensure spread if planting deep.

Use moisture blanket after pouring the gravels

Now comes the easier part. Simply pour the bags of gravel onto the surface. After that, you will need to brush the gravel into place and roll over the root membrane. If you want a thicker layer of gravel, add more on top.

After placing the gravels, spread out a moisture blanket, leaving a 6-8 inch space around the corners. Old clothes, towels, and sacks can be used as a moisture blanket. Add another layer of gravels and spread large pieces around the edges for proper drainage. Attach the pond liner to the building corners using flashing tapes to prevent water from getting beneath it.

Decide on the watering system of rooftop gardening

After considering the unique microclimates of your rooftop, selecting suitable plants, and properly layering your materials, you must also plan for efficient watering. Heavy buckets of water are impractical, so consider installing a water storage or automatic irrigation system. A rainwater harvester is a great way to ensure better water utility. Remember to water frequently in the summer months to prevent scorching. With all these steps in mind, you are now ready to create your lovely rooftop garden.

Required materials to build your rooftop garden

The following are typical materials needed for a rooftop garden, but they may vary depending on the type of roof:

Some of the typical materials that you may need for a rooftop garden include plants, growing containers, growing medium, decking, or other material that can be walked on. Additionally, you may want to consider adding seating, wildlife features, greenhouses, or composters to your rooftop garden to make it more functional and sustainable. By choosing the right materials for your rooftop garden, you can create a beautiful and thriving space that will enhance your home or building and provide numerous benefits for you and the environment.

Now that you know everything about how to build a roof garden, it’s time to gear up for creating a beautiful breathing space on your terrace. Constructing a roof garden is not a job that can be done alone, and it’s important to find someone to help you with the entire process. If you lack the confidence to pull it off on your own, it’s best to consult a specialist before starting the project.

Three main problems to build your rooftop garden

There are many ways to create a rooftop garden, but typically, it involves three main components to address the primary challenges of rooftop gardening.

A PVC structure

The plants are wrapped in bamboo fencing to provide protection against the strong winds that can be particularly harsh on a rooftop garden.

Self-watering containers

One solution to reduce the amount of time spent carrying water to the rooftop garden is to install an irrigation system. This will ensure that the plants are watered regularly, even if you are unable to do so for a few days. An irrigation system can be as simple as a series of soaker hoses connected to a timer or a more complex system that includes drip lines, sprinklers, and sensors to detect moisture levels. Installing a rainwater harvesting system can also help to reduce the amount of water that needs to be brought up to the roof garden.

A homemade soil mixture

The aim is to promote a fruitful harvest by using top-notch soil that does not require constant fertilization.

main problems to build your rooftop garden

Suitable plants you can grow on a roof garden

Rooftop gardens are becoming popular because they provide an opportunity to create decorative or edible gardens in otherwise unused spaces. With a rooftop garden, one can grow a wide variety of plants including shrubs, grasses, annuals, perennials, herbs, vegetables, and even dwarf fruit trees. The choice of plants will depend on factors such as climate, budget, available space, and the building’s structural capacity. A rooftop garden can be designed to be low maintenance, making it an ideal option for those who don’t have much time for gardening.

Suitable plants you can grow on a roof garden

Caring your rooftop garden

Here are some things to keep in mind when setting up a rooftop garden:

Start with a plan:

Before starting your rooftop garden, you should also consider how much sunlight your rooftop receives, and what kind of plants would thrive in that environment. Additionally, you should think about the type of soil and irrigation system you will need, and if you will need to install any protective barriers to prevent your garden from being damaged by wind or harsh weather conditions.

Consult with the building engineer:

It is important to consult with the building manager or engineer before starting a rooftop garden to ensure that the roof can support the weight of your garden. The weight of soil, plants, and other garden components can add up quickly, and it is crucial to make sure that the roof is structurally sound and can bear the load. Additionally, building codes and regulations may have requirements for rooftop gardens, such as waterproofing, fire resistance, and safety features. Consulting with the building manager or engineer can help you understand any such requirements and ensure that your garden is safe and compliant.


Waterproofing is indeed one of the most crucial factors to consider when setting up a rooftop garden. You need to ensure that the waterproofing solution you choose provides adequate protection against water damage and prevents water from seeping into the homes below. It should also be able to accommodate any physical or thermal movements of the building without compromising its durability and protection. A professional waterproofing contractor can help you choose the right waterproofing system based on your building’s construction and other factors. It’s essential to get it right to avoid costly water damage repairs down the line.


It’s important to check with your landlord or building code to ensure that rooftop use is allowed and to understand any regulations that may need to be followed. Some common concerns include fire regulations, building height restrictions, and accessibility requirements. It’s always better to make sure that your plans are within compliance with the regulations to avoid any issues in the future.

Structural Integrity:

It’s essential to determine the load-bearing capacity of the roof before setting up a rooftop garden. Consult with a structural engineer or a professional rooftop gardening service to assess the weight-bearing capacity of the roof and determine which types of containers and growing media would be appropriate. Using lightweight materials can help reduce the load on the roof. The specialist can also advise on drainage solutions and waterproofing to protect the roof from damage. It’s important to follow all building codes and regulations to ensure the safety and stability of the rooftop garden.

Use sturdy materials:

Larger sized pots such as half-barrel planters can be a good option for containers in a rooftop garden. These larger containers can hold more soil, which helps to prevent drying out, and are less likely to blow around in windy conditions. Additionally, they can accommodate a wider range of plants, including small trees and shrubs. However, it’s important to make sure that the weight of these larger containers is within the weight limit that the roof can safely support.

Check into access:

It’s important to ensure that you have a convenient way to transport your materials and supplies up to the rooftop garden. If you live in an apartment building, you should check with your building management to make sure you’re allowed to use the elevator for this purpose. If not, you may need to carry everything up the stairs, which can be challenging and tiring. You may also want to consider investing in a small handcart or wheeled dolly to make the job easier. Additionally, if you have a roof access door, make sure it is in good working condition and easy to use.

Pick the right planting medium:

Using potting soil is highly recommended for rooftop containers and raised beds. Potting soil holds water more effectively than garden soil, which is essential for plants growing in containers as they can dry out quickly. Potting soil is also lightweight and will not compact over time, which makes it easier for plants to grow roots and absorb nutrients. Additionally, potting soil is often sterilized, which can help prevent the spread of plant diseases.

Sun and Heat:

It’s important to observe the amount of light your rooftop garden will receive. While most roofs get full sun, if your roof is mostly shaded by neighboring buildings, it would be best to grow plants that thrive in low-light conditions. Additionally, if your roof is painted black, it will absorb more heat than a white or silver roof, so you should consider selecting plants that are more heat-resistant.


One of the challenges of gardening on a rooftop is the strong winds that can damage or even uproot plants. It is essential to identify the areas on the roof that are most vulnerable to wind and to plan accordingly. If your roof is unshielded by adjacent buildings, consider installing a well-secured trellis or windbreaks to protect your plants. Alternatively, choose low containers that hug the perimeter walls to minimize the impact of strong winds.


It’s important to have a drainage system in place for excess water, as it can damage the building and surrounding areas if left unchecked. Additionally, a drainage system can help conserve water by allowing for its reuse in the garden.


Having a storage area is an important consideration when setting up a rooftop garden. It’s always a good idea to have a designated space for tools, gloves, fertilizers, and other gardening supplies. This storage area can be in the form of a shed or simply a waterproof cabinet. Having a storage area will keep your rooftop garden organized and make it easy to find what you need when you need it. Additionally, if you have limited space, you might consider incorporating benches or seating that double as storage to make the most out of your rooftop area.

Caring your rooftop garden


In conclusion, building a rooftop garden can be a rewarding and sustainable way to utilize an underused space, whether you live in an apartment or have a flat roof on your property. However, it requires careful planning and consideration of various factors to ensure a successful garden.

The key points to keep in mind include researching building codes and consulting with the building manager or engineer to ensure the roof can support the weight of the garden. It’s also important to waterproof the garden to prevent water damage to the homes below, choose the right containers or raised beds, use the appropriate soil and fertilizer, and consider factors like light exposure and wind conditions. A well-designed rooftop garden can not only beautify your space, but also provide you with fresh produce and a relaxing oasis in the midst of a bustling city. With the proper planning and maintenance, a rooftop garden can be a sustainable and enjoyable addition to any home or building.

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