Bourne End 3


In 2011 Owlsworth Roofing successfully secured the subcontract to supply and install a Sarnafil green roofing system on the new extension at Beddington Park Primary School in South West London.

The basic structure is a steel frame and metal deck installed by a specialist contractor while all other elements of the Sarnafil green roofing system were installed by Owlsworth Roofing.


The steel frame and metal deck are installed flat and a Kingspan TT47 cut to falls insulation scheme is installed over a Sarnavap vapour control layer to provide drainage falls to the roof.

The insulation scheme fits together like a jigsaw puzzle and has a combination of 3 layers of flat and tapered boards to a maximum thickness of 225mm   


On the green roof areas of the building the Sarnafil membrane is laid loose over the insulation boards and only secured around perimeters and penetrations. The weight of the green roofing system is more than adequate to hold the Sarnafil in place.

On areas where the Sarnafil will not be covered such as the back of the rooflight the Sarnafil membrane is adhered to the facing of the insulation board with Sarnacol adhesives

Rooflights of all shapes and sizes, extract vents, outlets, soil vent pipes, fall arrest system posts and an access hatch – all supplied and installed by Owlsworth Roofing -  are sealed by our trained and experienced Sarnafil registered employees using hot air welding techniques to provide a guaranteed water tight roof



Before the green roofing system is installed on top of the Sarnafil membrane an electronic integrity test is carried out by an independent specialist contractor as a final check that the roofing system is 100% watertight 



The end result is a totally water tight environmentally friendly green roofing system that can provide a habitat for local plants and wildlife, helps the new building to blend into its surroundings in the community and reduces the impact of heavy rainfall on the local drainage network by draining the roof over a period of days rather those critical hours during periods of heavy rainfall  


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