Case Study The Withens (Sika)

Case study The Withens

Client: Bridgestone Construction
Project: The Withens, Liverpool
Size: 2100m2
Product: Sika Sarnafil Single Ply


About the Project:

The Withens is an Extra Care and Affordable Rent dementia project in Stockbridge Village, Knowsley. This project involved the creation of 90 new homes including 64 Extra Care apartments and 26 new Extra Care bungalows.


Key challenges:

This project had some key challenges that we needed to overcome. These included

  • The flashing was applied around the steel channel of the balcony base which needed to be dressed.
  • We needed to develop a plan to make a safe workplace as there was strong winds in the location
  •  We needed to develop a strong relationship with the forklift driver, as many lifts were needed.


The System:

For this roofing project we created a mechanically fixed single ply roof. We used a Sarnavap 500e as a vapour control barrier which is polyethylene based, remaining flexible at low temperatures. This vapour control layer is also resistant to chemicals and ageing, as well as being completely rot proof, and providing a very high level of water vapour resistance, which makes this perfect for residential properties.

For the insulation layer we opted for a 180mm PIR Insulation board offering a high level of thermal insulation for this building.
The single ply membrane we opted for was a Sika Sarnafil S 327-15 EL Membrane, with a depth of 1.5mm, in a light grey colour. This membrane is an effective waterproofing sheet made from premium-quality polyvinyl chloride (PVC), and this is also polyester reinforced. This single ply membrane is resistant to UV and has proven to maintain a high performance over decades.

We created a mechanically fixed system, ensuring that the roof would thrive in all manner of weather conditions, for a long period of time.

The project was finished with a trim finish to the parapet.

We also installed 25mm tissue faced insulation boards that were fixed to the upstands, and installed flashing to these upstands too.


The Result:

At the end of this project:

⦁ Our installation was fully inspected by the manufacturer for the 25 Year guarantee.
⦁ The roof was independently tested by an electronic integrity tester. Both field inspectors were very happy with the standard of work completed.
⦁ Very happy client with a new roof installed 2 weeks ahead of schedule.

Case study The Withens