Green Roofs are, without question, the “high fashion” contemporary solution of choice.

Typical green roof on structural tray

Sustainability is a key aspect of any building envelope specification these days. Hence these are good times for the green roof industry, despite the general economic downturn in recent years.

Even if environmental considerations were not such a hot issue, there would still be a mountain of justification for choosing a green roof structure:

• Studies in the UK suggest that a planted roof surface will retain 100% of rainfall where 3mm falls, up to 80% between 3mm and 23mm. One example shows 73% of water was retained where 41mm fell over a 47 hour period. By retaining rainfall, a green roof reduces the peak flow level, lowering the impact on the building’s environment and drainage systems.
• Arguably unrivalled aesthetics, reducing the visual impact on the surrounding environment.
• Complete harmony with the current requirements of many local planning requirements.
• The potential for enhanced thermal and acoustic performance.
• Reduction  in  the effects of solar gain.
• They are installed to low pitches, minimising the supporting structure.
• Minimal long term maintenance.

That said, all of these benefits and the wonderful bio-diversity that green roofs promote, come at the price of a considerable roof load.

A sedum mat based green roof could impose an additional load of 75kg/m2.  Fully saturated turf based build could see this load rise to 250kg/m2.

Typical green roof installation on perforated structural roof deck

Small wonder, then, that structural metal roof decking has played a key role in the adoption of green roofs. It can span up to 6 metres, eliminating the need for much of the secondary structure.  It is rapidly installed, lowering fixing costs and reducing construction timescales.

Decks and trays can be bundled and loaded in large quantities, resulting in a vast roof coverage area per site delivery. This represents a very worthwhile reduction in embodied energy levels, via lower numbers of deliveries to site and other related vehicle movements, unloading and storage activities.

If you require any technical assistance regarding the use of structural metal deck with green roofs or guidence on using the correct type of deck for your project, please call the technical team on 0845 30 88 330.