Green Roof Living Roof

Green Roof Development with LECA® LWA

Lightweight Replacement for Traditional Soil

Green Roof and Living Roof

The Emergence of the Green Roof: The rapid growth within our cities has resulted in the loss of open spaces which has created a considerable deterioration of living conditions across the UK. However, we have been able to counter this with the development of large green areas also known as a green roof or living roof within our residential, commercial and industrial complexes – specifically designed to improve living and working conditions.

Areas that were not previously used can turned into communal living spaces providing fresh clean air and sanctuary for the living and working community - providing a direct improvement of the places where we live and work and consequently generate an increase for our well-being.

Living roof for safe habitat

Habitat and Biodiversity

The ecological benefit of a verdant rooftop is partially the result of storage of rainwater and its reintroduction to the natural water cycle, of the increased humidity of the air, of dust control, of the improvement of the microclimate and of the creation of a habitat for plants and animals.

Building Physics

In addition, an important aspect of rooftop gardening for the designer or owner of the building is the protection of the construction that lies under the roof. The leaves over the roof provide acoustic insulation as well as thermal insulation, both against summer heat and winter cold, and, in general, a drastic reduction of the physical and mechanical efforts of the roof structure as a result of the reduction of the thermal amplitude and of the minimization of the ageing of the basic structure of the roof caused by the action of UV rays.

Studies over long periods of time demonstrate that rooftop gardens increase the useful life and insulation of roofs.

Water Management

A well designed green roof will give a substantial contribution to reducing the impact of run off on the storm water drainage system, and reduce the likelihood of local flooding.

Green roofs store rainwater in the plants and growing mediums and evaporate water into the atmosphere. The amount of water that is stored on a green roof and evaporated back is dependent on the growing medium, its depth and the type of plants used. In summer green roofs can retain 70-80% of rainfall and in winter up to 25%. This retention could make a huge difference in managing the downstream water management systems.

Green Roof Design

Green Roofs Can Cool Down the Surrounding Area

“Planting trees and arranging green areas will, besides create a beautiful living environment, cool down the surroundings. Projects have proven that covering London with green roofs, green areas and correct water elements, the temperature will drop by 8oC. Furthermore, if you add the impact from eliminating dark construction surfaces, the temperature impact will be even higher.”

Bjørn Lomborg, “Cool it” and reference “Greater London Authority, 2006”


Pneumatic Delivery
Pneumatic delivery of LECA® LWA

It is possible to apply LECA® LWA on every type of flat or slightly sloping roofs of buildings, underground car parks, etc. There are two types of green roofs, extensive and intensive, differentiated mainly by the cost, depth of growing medium and the choice of plants.

There are numerous reasons for choosing LECA® LWA for this purpose:

• Natural, light-weight product
• Neutral and inert
• Lends support to root growth
• High air conductivity
• High hydraulic capacity
• Resistant to freezing
• Structurally stable
• Stable quality
• Good thermal and acoustic characteristics
• Fire resistant

When utilising the green roof area as an area for recreation and more flexible use, very often it will be a need for building slopes and variation in the terrain. Lightweight solutions are preferable to avoid limiting extra load on the underlying structures. A well proven and efficient solution is to use LECA® LWA 10-20 mm. Before installation of the LECA® LWA, the final surface level is decided by levelling.

Green roof with Leca LWA


Extensive green roofs are characterized by the low weight due to limited thickness (typical 50 – 150mm growing media thickness) and very special plants which must be low and hardy, typically alpine, dry land, or succulent plants. Sedum type plants are commonly used. The growing medium, typically made up of a mineral-based mix of sand, LECA® LWA and peat is designed for the chosen plants.

Extensive Green Roof with LECA LWA

Typically the plants are watered and fertilized only until they are established, and after the first year, maintenance consists of two visits a year for weeding of invasive species, safety and membrane inspections.

Intensive green roofs are characterised by their use as a ‘garden’ in much the same way as people would use a garden at ground level. In having an increased soil depth (20 – 200 cm), the plants can be more diverse and utilize trees, shrubs and other landscaping aspects. This allows for the development of a more complex ecosystem. Requirements for maintenance - especially watering - are more demanding and ongoing, and irrigation systems are usually specified.

Intensive Green Roof Design with LECA LWA

Interview with the Vice President of Green Roofs and Walls

Interview with the Vice President of Green Roofs and Walls
Interview with the Vice President of Green Roofs and Walls



Green Roof Calculator
Green Roof Calculator for assessing the impact of LECA LWA


We have a team of representatives in the UK with extensive experience and knowledge on utilising Leca® Lightweight Expanded Clay Aggregate on a variety of Green Roof projects.


For a free quote and consultation on Leca® Lightweight Expanded Clay Aggregate contact Leca® UK:

TEL: 0844 3351770 


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