Construction Management is the highest circulation construction-based publication serving the UK built environment.
Technical
How to stop green roofs turning brown
Chris Roddick Bauder
A common problem with green roofs, particularly during hot summers and droughts, is ensuring they perform as intended. Chris Roddick explains.
A Bauder green roof at Lagg Distillery in Scotland (image: Bauder)
Green roofs are growing ever more popular. London, which has 42% of the UK’s market, now has over 1.5m sq ft of green roofs on its buildings. Last month, this niche sector celebrated the first World Green Roof Day on 6 June.
However, while green roofs are always well intended, one of the greatest challenges, particularly at this time of year, is ensuring they are as healthy on the day of installation as when the building is handed over to the client.
One key reason for failure is the lack of establishment watering
at the time of installation.
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Roofs are hostile environments for all plants. There is an
increase in wind at higher levels and the reduced depth of substrate can dry
out quickly when surrounded by a warm building. The perimeter of a planting
area is more prone to drying than the centre and so sufficient watering at
these vulnerable areas is especially important.
All green roofs require some form of establishment watering
which should continue until the plants have developed a sound root system. Establishment
watering critically needs a fully operational rooftop water supply with
adequate pressure and flow rate at the point of watering, delivered via surface
sprinklers.
This initial watering programme is in addition to any fitted irrigation system that will come into operation at a later stage. In warm weather, watering should take place in the early morning or evening to reduce water wastage through evaporation. Different forms of vegetation will require different watering schedules to meet the needs of the plants.
In warm weather, green roofs watering should take place in early morning or evening (image: Bauder, Simon King)
It is not just about watering though; it is also important
to respect the vegetation and avoid physically damaging the plants from using
the green roof as a walkway or storage area while the rest of the building
project is completed.
These measures should ensure the roof stays as green as was intended at installation – rather than turning brown.
10 key points to ensure a green roof is successful at installation
Ensure all other roof works are completed before the green roof is installed.
Test the watering system, ensure there is a working water source at roof level with sufficient pressure at the point of watering.
Do not try to install living vegetation on extremely hot, sunny days.
Install any vegetation on the day it is delivered.
If using vegetation blankets, ensure they are laid carefully, and additional substrate is used to patch any open joints.
Water the vegetation (even in winter) and fertilise if required.
Watering should take place in the early morning or evening to reduce evaporation.
Avoid any trafficking of the roof.
Avoid any storage of materials on the roof.
Continue to water the roof as required for the whole establishment period.
Chris Roddick is green roof product manager at Bauder.
The January/February 2026 issue of Construction Management magazine is now available to read in digital format.
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