What is a Sedum Roof?
A sedum roof is a specific type of green roof made out of entirely, you guessed it, sedums.
Sedums are perennial succulents with properties ideally suited to life on a green roof. Generally an extensive one. Their incredibly hardy, low growing and lightweight nature is what makes them such a popular choice.
Why are Sedums a good choice for a Green Roof?
Sedums are tough little buggers. But they aren’t just one trick ponies and these plants have multiple properties that make them ideally suited to life on a rooftop, including:
- Lightweight
- Require limited growing medium and have a shallow root structure
- Perennial
- Incredibly hardy
- Drought tolerant
- Low maintenance
Dependent on the type of living roof, there are certain essential properties plants must have to survive and be suitable for green roofs.
Shallow rooted plants that don’t require much growing medium minimises the chance of root and structural damage, whilst limiting the load placed on the roof.
And as the roof will be forever at the mercy of the elements – you’re unlikely to add a greenhouse up there – it’s important the plants know how to survive.
On top of that you’re looking for plants that don’t require a lot of maintenance and in an ideal scenario, are cost effective.
Sedums metabolise carbon dioxide at night and convert it into malic acid. In the daytime, the malic acid decomposes and photosynthesis occurs. So during hot, dry conditions sedums minimise moisture loss.
How much does a Sedum Roof Cost?
- The cost of a sedum roof depends on the method of planting, roof type and number of plants recovered
- Pre-grown sedum mats are the most expensive method of building a sedum roof
- Seeding the roof yourself is the cheapest
There are a number of different factors that influence the cost of a sedum roof. And we have an entire page dedicated to how much a green roof costs. Which is a great starting point.
Arguably the biggest cost is the size of the project. The bigger the roof, the more expensive the project will be. Obviously.
Then you’ll need to consider what type of sedum plants you’d like to use. Whilst the majority of very good value, pre-grown sedum kits can cost several thousands of pounds for a larger project. Whereas small sedum DIY projects can be created for a few hundred pounds. All you need is:
Finally you’d need to understand your roof’s structural integrity. Does it need substantial work? Can you do it yourself? If the answers to these questions respectively are yes and no, then intrinsically the project is going to be more expensive.
And when all of that is said and done, you’d need to think about installation and maintenance.
Types of Sedum Roofs
There are four primary types of sedum roofs: sedum blankets, trays, plugs and seeds.
Sedum blankets can cost of thousands of pounds and are better suited to much larger projects. They’re brilliant in their instant green effect, lack of required maintenance and quality. Modular trays are a brilliant alternative if you still want the above effect, without spending thousands of pounds.
Seeds and plug plants are a brilliant solution for smaller DIY projects where you’re happy to spend a little time (and elbow grease).
Roof Type | Cost | Maintenance |
|---|---|---|
Sedum blanket | £££ | Low |
Sedum trays | ££ | Low – medium |
Sedum plugs | ££ | Medium |
Sedum seeds | £ | Medium – high |
When thinking of sedum roofs from an intensive vs extensive green roof perspective, things are less clear.
Sedums are generally better suited to extensive roofs, because of their hardy, lightweight nature. But their instant, year-round green effect make them an equally excellent option for intensive roofs. They just aren’t as essential an option. You have more choice.
How to Install a Sedum Roof
Before you setup a sedum roof, you need to have a structurally sound rooftop, with a suitable load-bearing capacity that is also waterproofed. The basic steps to building your own green roof is here and must be followed to start with.
Once you have the foundations setup you can think about creating a sedum-specific roof. And there are multiple ways it can be approached:
- Seeding: The most cost effective, slowest route to creating a sedum roof
- Plug-planting: Purchasing more expensive-grown sedums to ‘plug-plant’ into your roof’s growing medium provides an instant green look and reduces risk
- Modular trays: Pre-grown trays that can be purchased in increments and ‘clipped’ together have grown in popularity in recent times. Whilst they’re more expensive, they provide the best all over green look
- Sedum mats: expensive, pre-grown mats of sedum that can be 100s of metres squared
Sedum Roof Maintenance
Whilst sedums are relatively hardy, low maintenance plants, sedum roofs do require a little due care and attention.
Unlike wildflowers, or annuals, sedums don’t require much (if any) watering or deadheading. Even surviving through harsher winter months. We’d just recommend annual weeding.
If you installed the roof with pre-grown sedum matting, your maintenance would be significantly lower. In contrast, if you planted seeds – or seedlings – they’d require much more maintenance and care to thrive, survive and – in the long run – flourish.
Top 7 Sedum Roof Benefits
Sedums are the perfect plant choice for rooftops for multiple reasons. They’re lightweight, fuss-free and highly resistant to most weather conditions.
You can read more about the benefits of a green roof here. This page is specific to sedums.
- Sedum plants have shallow root systems, which allows for a shallow, lightweight substrate
- Sedums are incredibly hardy, low maintenance plants
- Cost - sedums are relatively inexpensive. To buy and to maintain
- Low rate of growth - this minimises the load placed on your roof
- Drought and extreme weather resistant
- Improves energy efficiency and reduces bills
- Improves air and water quality
Sedum Roof FAQs
As green roofs go, sedum roofs are the cheapest viable option. A DIY sedum project could cost as low as a few hundred pounds. A larger residential or even commercial project can cost tens of thousands.
Sedums are long-lasting, durable plants that are cheap to purchase, install and care for.
Much like typical green roofs, sedum roofs can last up to 50 years and beyond.
With annual maintenance and the necessary structural solidity sedum roofs should actually increase the lifespan of your current roof. Sometimes by 20 years or more.
Sedum roofs usually range in thickness from as low as 6cm to as much as 30cm.
These extensive roof varieties are much thinner than their intensive counterparts, because sedums only require a small amount of growing medium to flourish.
Yes you can install rooftop sedum on any pitch of roof at all.
Most commonly green roofs, particularly the DIY versions, are built on flat roofs. And they’re substantially more easy to create. But sedum plants can bed in to any sloped roof.
Yes, although the key thing to consider here s no the sedum on the roof. More the structural solidity of the roof.
If the roof was solid enough to add sedum onto it – potentially adding 100s of kilograms of weight onto the roof – it’s almost certainly safe to walk on.
But if you do want to walk on your sedum roof, it’s worth considering adding walkways onto it.
2 Comments
Hi I am wanting to plant a strip of sedum roof on my extension – 1m x 7m. From what I have read I need a waterproof/rootproof layer, a substrate and can use planting trays but where can I purchase the component parts so I can collect my plants and plant up over a period of time?
Hi Carol – sorry my website has had so many spam comments it’s been hard to separate the wheat from the chaff.
When you say the component parts, do you mean the plants themselves? Or do you mean sedum trays?
I have a page on creating a DIY green roof here: https://www.greenroofguide.com/green-roofs/diy/
But for pre-planted sedum layers Roofing Superstore have some great trays: https://www.roofingsuperstore.co.uk/product/wallbarn-m-tray-modular-sedum-wildflower-green-roof-540mm-x-540mm.html