Harefield, United Kingdom

The existing asphalt roof had begun to show signs of blistering and slumping, which needed to be addressed to prevent failure, and the insulation required an upgrade to conform with the changes in the Building Regulation Part L.

Hareifled Hospital Sika Sarnafil roof project
Hareifled Hospital Sika Sarnafil roof project

Flat Roof Project Requirements

In addition to the technical challenges there were other more sensitive issues to address. How do you reroof a hospital when it’s still in use? How can water ingress during refurbishment be prevented? How can we meet the 10 year guarantee requirements within budget? How can we find a system that can overlay the existing waterproofing without stripping? Finally, how many systems can meet all these requirements and not have the need for naked flames or bitumen boilers?

Sika Single Ply Roofing Solutions

Sarnafil Plus provided the solution. The existing concrete deck, with thin insulation and asphalt waterproofing was overlaid with SarnaTherm Insulation bonded to the existing covering using Sarnacol 2162. Sarnafil G410-12EL single ply membrane was then adhered to the insulation using Sarnacol 2170. This ensured that there were no naked flames or hot works.

The critical areas over the operating theatre and intensive care unit encountered no disruption, nor did they experience any water ingress due to the fact that the existing roofing covering was left intact. There was also no noise from mechanically fixing into the concrete deck. Sarnafil Plus provided design advice and produced detailed drawings to the client and contractor on every aspect of the works.

"Harefield Hospital was a fantastic project with the opportunity not only to do a great job but also to provide a full integrated service. The knowledge and technical backup provided by Sarnafil, both on and off-site, ensured that the project was a success and all objectives were met." Andy Bacon, managing director of Fenland Flat Roofing

Products Used

Sika Sarnafil G410-12EL


Sarnacol 2162

Sarnacol 2170