Victoria Way Car Park Green Roof

Client Background

Woking Borough Council earmarked 3 key locations to create a greener and cleaner town centre using the power of nature: Victoria Square, Dukes Court and Middle Walk.  Victoria Square was identified as a key location, to emphasise what can be done using natural systems, and plays an integral role in Woking’s transformation.

Featured Solutions

• Viritopia GrufeKit Green Roof System (Extensive)
• Viritopia Living Roof (Intensive)

• Size: 4,200m²

Living roofs and walls

As well as the 1,700m² living wall on the façade of the multi-storey car park in Victoria Way (you can get an insight into the creation of this here), we designed and installed the 4,200m² of green roofs over two levels of the car park.

Intensive green roof

The first level with a green roof, level 10, involved an 800m² intensive green roof, which is a green roof that has a deeper substrate and therefore allows greater design scope and plant choice.  The purpose of the green roof on level 10 was largely improving local biodiversity, and to screen the adjacent hotel windows from the car park view.

Weight restrictions

However, there were weight restrictions on this level, which meant we designed the roof to have a deeper substrate in the middle of the roof, to a lot shallower at the edges.  This means the green roof is mounded, with the soil depth ranging from 150mm at the perimeters, to 800m in the centre.

Balancing ecological value with aesthetics

Whilst the planting around the permitter of the roof, where the soil is shallower, are all smaller species that will add ecological value such as wildflowers, the species used in the centre with the deeper substrate are larger plants like shrubs and trees.  These will provide slightly less value for local ecology but will be used for screening the car park from the view from the windows of the Hilton Hotel next door.

Extensive sedum green roof

On the design for the 3500m² green roof on Level 11, the focus was on air quality.  An extensive green roof was used here, which is characterised by a lot shallower substrate (and therefore lowered weight loading) and plant species which do not need much soil space to grow.

Blue roof

Succulents were used on this green roof to assist with air purification, and a blue roof in order to minimise stormwater runoff, mitigating the build-up of water in the drains and therefore reducing the risk of flooding.

Grown bespoke

To create the requested basket weave pattern, we grew sedum bespoke for the project, so instead of having 10-12 varieties of sedum per module (which is our standard), we reduced it to 2-3 varieties.  This meant consistency and allowed us to create a clear pattern on the roof.  Sedum plants which have flowers of pink or red formed one weave, whilst sedum species with white and yellow flowers formed the other.