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QUESTIONS & ANSWERS ON
SEDUM ROOFS

Green roofs, sedum roofs, living roofs – so many names for the same thing. Here on our questions & answers page, you can find answers to the most common questions about our sedum roofs.

If you can’t find an answer to your question, then contact us here for more information.

What is a sedum roof?

Sedum roofs are roofs covered with sedum plants, a type of stonecrop, which are particularly suitable for the harsh conditions roofs are often exposed to. These plants are known for their ability to thrive in varied weather conditions, including strong sunlight, strong wind and extreme temperatures. Therefore, they are also excellent for the Danish climate, which is known to vary a great deal throughout the year, with high and low temperatures.

Can sedum trays be placed directly onto roofing felt?
To lay out our sedum trays, a water-tight membrane is required, which is approved for lying underneath a green roof. Roofing felt is often a good and highly durable roof underlay for a sedum roof. Your roofing felt supplier can advise you about the correct underlay for your green roof.
Do sedum roofs need watering?
Sedum plants are extremely hardy. They can easily tolerate a dry summer. You will typically find that they do not flower so much during a dry period. The plants go into a state of dormancy, and only use energy for their survival, not for reproduction, which the flowers are an expression of. The roof can turn reddish during dry periods, but as soon as it rains, the plants change colour and become green and lush again. In very long periods of dry weather, you can water your green roof thoroughly every 14 days to maintain an attractive sedum roof. But this is not a “must”.
Is it only roofs with a gentle slope that can hold sedum?
No, fortunately not. We can supply green roofs for surfaces with a slope of up to 45 degrees, but, depending on the slope, the construction may have to be mounted with additional support profiles. Our 60 mm sedum trays can be used on a roof slope of up to 25 degrees. If the roof has a steeper slope, our 80 mm sedum trays should be used.
Will sedum roofs have a lot of flowers?
It varies. We produce our sedum trays with cuttings from around 12-15 different sedum types. This is to ensure the best growing conditions on the roofs, where the sedum plants may experience many different conditions. They have to withstand winds from the North Sea and heat from the cities, and they can also end up being placed entirely in the shade. The number of flowers will depend on the growing conditions on the roof, and will be reduced in the course of the year. Therefore, we always start by having a lot of plants in the trays. Wherever our trays are positioned, therefore, we are certain that there will be sedum plants that survive and flower beautifully from May to September.
When are support profiles necessary on sloping roofs?

With roof slopes of over 15 degrees, support profiles must be used to keep the sedum trays in place.

Please contact Nature Impact for guidance on support profiles.

I only need a 15 m2 sedum roof for my garage. Can I buy it from you?

We don’t sell sedum roofs to private individuals, but you can contact your local carpenter, roofer or timber supplier. They are sure to assist you further with your request.

Are your green roofs maintenance-free?
No, green roofs from Nature Impact are not entirely maintenance-free. To maintain the 5-year warranty on a sedum roof from Nature Impact, the roof must be checked and maintained twice a year. The roofs have to be fertilised, and it may be necessary to remove small branches and twigs or other unwanted material that blocks the light. The maintenance also has to be documented by completing the Operation & Maintenance form.
Do sedum roofs need fertiliser?

The sedum plants are placed in relatively shallow trays with a growth medium, and need to be fertilised twice a year as recommended.

You can read what type of fertiliser you should use for your sedum roof in our operation and maintenance plan. You can buy fertiliser for sedum from Nature Impact. There is also the option of a service agreement, whereby we regularly fertilise and tend your sedum roof.

How long can I wait from delivery before laying the green roof?

Once we have delivered the sedum trays, the green roof should be laid within 48 hours to avoid drying out and damage to the growth medium.

Why do sedum roofs become red?
The sedum plants change their colours with the season. Towards the end of winter there is not much nutrition left in the soil. At this time, the plants need fertiliser, water and warmth to regenerate and revive the chloroplasts. When the warmth begins to be felt during the spring and the roof is fertilised manually, the plants change colour and become green and lush again.
How much does a sedum roof weigh?

The weight is always measured in the roof’s saturated state, i.e. the heaviest weight. Nature Impact’s 60 mm sedum trays weigh 50 kg per m2.

The weight of the 80 mm sedum trays is 65 kg per m2.

It’s always a good idea to have the bearing capacity of the rafters checked before laying a green roof, so you are sure the construction can bear the weight of the sedum roof.

How much does a sedum roof cost?

It’s difficult to give a clear answer to how much a sedum roof costs, as the price depends on several factors. The size of the project and the mounting costs in particular are decisive for the overall price. Contact us to discuss what a sedum roof from Nature Impact costs.