Roof-top gardens have been around for centuries, with roots dating back to Renaissance-era Italy. These structures provide beautiful aesthetics and are practical for those who like to garden. They can also benefit the environment by absorbing heat from the sun and cooling the interior. Before planting, there are some things you need to know. Read this list of five tips for starting a roof-top garden.
1. Building Code
The first thing you should account for is the building code — or you’ll need to consult with your landlord if you have a flat. Ask your local council to see if there are any laws regarding roof-top gardens. There may be regulations due to fire safety and structural integrity.
In 2019, the Grenfell Tower fire caused the U.K. to overhaul its building regulations, some of which impact roof-top gardens. There are now details you must consider. For example, your soil must be at least 30mm deep, and gravel or shingle strips must surround penetrating structures. You’ll also need metre-wide breaks every 40 metres to create a fire break.
2. Garden Type
The next thing to consider is your goals for the roof. Decide in advance what type of garden you’re trying to create. Your selection will significantly impact the roof because of its weight. Some common types you may see include:
- Extensive: An extensive green roof is the simplest form you’ll see. These structures typically have perennials and mosses growing. Extensive green roofs don’t need much maintenance, which is apt if your roof isn’t easily accessible.
- Semi-intensive: The next step up is a semi-intensive green roof. These structures need deeper soil than the extensive roof, but you’ll be able to have more types of plants, like small shrubs and flowering plants. More maintenance — such as irrigation — is necessary, so you’ll need a roof you can easily access.
- Intensive: Intensive green roofs are likely what you imagine with roof-top gardens. They need deeper soil than semi-intensive structures. You’ll need even more dedication to maintenance because you can plant trees and create an entire lawn. The weight can be massive and the garden can be costly, but it offers opportunities for energy savings. Intensive roofs reduce heat islands and keep the interior cool.
3. Roof Durability
Another aspect of your roof to consider is the slope. Many roofs have slopes to dispose of rainwater during storms. Roof-top gardens are typical on flat roofs, which makes the most sense. However, it can have a negatve impact — flat roofs are more susceptible to water damage than sloped roofs.
Standing water can sit on the top for days, allowing mould and mildew to grow and metal to corrode over time. If your roof is flat, you’ll need to take precautions to ensure it stays safe for a long time. For example, clean your gutters regularly and trim trees with overhanging branches. Periodically get a roof inspector to ensure the structural integrity remains intact.
4. Water Sourcing
Another aspect to consider for your roof-top garden is accessing water. You’ll need to water year-round unless you have an extensive garden. Any garden beds, potted plants and shrubs will dry out if they don’t get adequate water.
You can assume responsibility for the garden and manually water the plants. Tools like garden hoses will be handy for connecting with nearby water systems or you can take advantage of modern technology with an automated irrigation system. These mechanisms are hands-off and will water plants for you, which is ideal if your roof is difficult to access.
5. Sunlight Access
Besides water, another fundamental point to consider is sunlight access. Most plants need around six to eight hours of sunlight daily to grow appropriately. Vegetables like tomatoes and peppers require eight hours of daylight, so you’ll want to ensure they have enough.
First, ensure surrounding buildings won’t compromise your garden. Tall structures may block your plants from getting adequate sunlight. Gauge how much direct sunlight comes to the roof because it will influence what types of plants you can grow in the garden.
Designing a Lovely Roof-Top Garden
Sustainability and eco-friendliness have become more popular ideas recently. One way to go green is with an extensive or intensive roof-top garden. Remember to inspect the building code or talk with your flat’s landlord to see what the regulations are. Then, have fun gardening and growing your plants.
Rose Morrison is a home living writer with over five years experience writing in the industry. She is the managing editor of Renovated.com and loves to cover home renovations and decor to inspire everyone to live their best DIY life. When she isn’t writing, you’ll find her baking something to satisfy her never-ending sweet tooth.