It is essential when designing a new roof, that careful consideration of the drainage system takes place, in order to ensure compliance with the relevant standards.


To assist the designer in the provision of a suitable gravity drainage system and in accordance with BS EN 12056 – 3: 2000 ‘Gravity drainage Systems inside buildings. Part 3 Roof drainage, layout and calculation and the Building Regulations Approved document Part H, Sika Limited offer a drainage calculation service for Sarnafil systems based on the use of our standard rigid rainwater outlet range. A service also covered as part of the Sarnafil Guarantee which, complete with our design insurance, indemnifies our work.


Using Sarnafil rigid outlets enables a hot air weld to be achieved between the waterproofing membrane and the outlet body, providing a reliable junction for the life of the roof without the need for clamping rings or sealants.  Our outlets have been tested to BS EN 12056, enabling the use of precise flow rates, resulting in more accurate calculations.


In order to obtain a project specific drainage calculation for your project, please contact your local Technical Advisor in the first instance to register the project.