recent projects 2010 - The National Audit Office

greenroof structures & planter systems

The NAO Project Requirements :

To design and build an external landscaping scheme and planting plan satisfying all of the following requirements as a minimum :

  • Meet the BREEAM commitments enhancing local ecology and increasing native species.
  • Improve the aesthetics of the NAO Building.
  • Create free standing areas of landscaping to include native plants & grasses.
  • Ensure that floor loadings are not exceeded by planters
  • Provide a covered area and benches for staff amenities.
  • Provide feeding posts and nesting boxes.
  • Provide 12 months aftercare and defects liability on the completed installation.

The Verdant Bridge Solution


We proposed a flexible solution exceeding the minimum requirements of the design objectives using modular components from our Wild® Planter System. We gave consideration to the softening of the relatively harsh environment, whilst complementing both the architectural style and historic nature of the NAO in the development of our proposals.

Biodiversity Proposal

We finally incorporated 35 different native species in total. With the use of large native trees avoided due to the inherent weight and maintenance implications, we strategically placed multi-stemmed native trees including Field Maple and Birch in the deeper planters. These can be readily maintained to

a manageable size of 3-4m and give important structure and diversity to the planting. A primary shrub structure consisting largely of evergreen species forms an intermittent boundary hedgerow. This is followed by a secondary shrub layer containing a mixture of shade-tolerant native perennials and finally sections of our 120mm Wildflower Meadow planter. We installed log piles within each planter to provide shelter for invertebrate fauna and bird feeders were installed along the hedgerows.


The installation of extensive native planting with multi-stem trees and both evergreen and flowering shrubs has a significant immediate visual impact that will increase steadily as the planting establishes over the next 2-3 years. The co-ordinated timber planter structures from our Wild® Range, whilst being relatively low-key, complement the architectural features of the NAO building with the timber.

being stained dark brown to match the Crittal window frames. Our design featured straight lines rather than curved forms, with a continuously stepped profile to disrupt the visually dominant walls and kerb lines. In addition we applied a resin-bonded gravel surface to a significant proportion of the macadam surface. This made for a cohesive design, helping to disguise the vehicular origins of the areas and make for greatly improved informal use of the staff seating areas.

Staff Amenity

Due to its North-Western aspect, different sections of the area had to be made available for informal staff use depending on the time of day or year, and the desire for sun or shade. We fulfilled this requirement with timber benches from our Wild® Range to match the planter structures both singly and in groups. The installation of a Wild® Greenroof WS2424 Structure as a smoking shelter equipped with a bench and planter screens also coordinated.