This week on the Sika Sarnafil blog we’ve invited Andrew Fuller, Technical Services Advisor and expert on all things single ply to answer your questions. We’re hoping to make this a regular feature, so if you have any burning queries, let us know!


It’s amazing how many people get in touch with the technical team on a regular basis about certain topics – we’re a rather valuable service, even though I do say so myself! I thought it would be useful to tackle some of the more frequently asked questions on this blog, making them available to everyone.

Andrew Fuller, Technical Services Advisor for Sika Sarnafil

Today’s focus is detailing advice. Complex projects, whether new build or refurbishment, can be a challenge from design and specification, right through to installation, without the correct planning and guidance. That’s where we can help, so here goes with some good questions…

What is the minimum upstand height required for a Sarnafil membrane flat roof?

Along with the minimum finished fall required for a flat roof (which can be found here), this is one of our most common questions in the Technical Department. Upstand heights should comply with the recommendations of BS 6229:2003: Code of Practice for Flat Roofs with Continuously Supported Coverings, which states that the waterproofing membrane should be maintained for a vertical height of 150mm above the finished roof level.


It is worth noting that on ballasted or inverted systems the finished roof level is taken from the upper surface of the ballast, for example paving slabs, green roof, timber decking.  


Achieving the minimum 150mm requirement will ensure the design follows good practice and will account for rainwater splashback and any snow build up (however unlikely it is). It also ensures that Sika Limited can provide a full comprehensive guarantee for the Sarnafil roofing system, providing it is supplied and installed by a Sarnafil Registered Contractor as per our normal recommendations.

Do you offer any products and accessories that will emulate metal roofs?

Yes, we have some great products that imitate the appearance of traditional metal roofing systems. We can provide two different decorative profiles. The Sarnafil batten profile is used to imitate a traditional batten roll on a lead roof and is installed in conjunction with our Lead Grey adhered PVC membranes – ideal for projects such as listed buildings and those where aesthetics are of high importance.


The alternative decor profile is specified when the designer is looking to replicate a standing seam metal roof finish and is available in various colours including Light Grey, Lead Grey and Copper Patina. Used with both our adhered and mechanically fastened PVC membranes, this product is suitable for most projects of various designs, shapes or pitches.


Both profiles are simply hot air welded to the waterproofing membrane by the Sarnafil Registered Contractor. If you require any further information on the aesthetic profiles - including standard details, case studies and product data sheets - these are all available from our Download Centre or alternatively please get in touch with our Roofing Technical Department on 01707 358500.

We have a project where air conditioning/mechanical extract services need to be fixed to a new Sarnafil roof. Do you have support and weatherproofing detail for this situation?

We can offer a number of detailing solutions where plant and equipment is to be mounted on the roof.  When securing support systems through the waterproofing layer it is important to ensure the correct termination of the membrane so it remains weathertight for the required period, but also that it meets the minimum 150mm upstand requirement as set out in BS 6229:2003: Code of Practice for Flat Roofs with Continuously Supported Coverings.


Alternatively non-penetrative systems can be considered (subject to loading) and with the installation of an appropriate protection layer – these can be an ideal solution while still maintaining the waterproofing integrity of the roof.


We have a selection of standard details available to download from our website (click here). However if you have any questions on the installation of mechanical equipment on Sarnafil roofs please contact one of our Technical Services Advisors in the Single Ply Roofing Department who are more than happy to help find an appropriate solution (01707 358500).

Can Sarnafil Single Ply roofing membranes be applied directly to an insulated flue?

There are various options for detailing around flues and penetrations through the Sarnafil roof system and therefore it is always worthwhile discussing the detail with one of our Technical Services Advisors to ensure the correct solution is proposed.


Nevertheless, we do have a specific standard detail for hot vent pipes which includes an appropriate heat resistant insulation and a supporting galvanised or uPVC pipe allowing the Sarnafil membrane to be dressed around the penetration and terminated the required minimum 150mm above the finished roof level. Should there be an insulated flue pipe, our standard Sarnafil vent pipe detail can be installed. These details can be accessed via our Download Centre or alternatively by contacting our Technical Services Department.

How can I ensure that there is a reduced risk of heat loss at junctions and details?

Use our products – that’s the straightforward answer! We’re proud to be one of the first flat roofing manufacturers to have launched our BRE Certified Thermal Details, providing specifiers assurance of the ‘as designed’ thermal performance of specific junction details. These details, which have been independently assessed by BRE, can be downloaded from the Sika Sarnafil Sustainability Hub. The use of these thermally modelled details will ensure the specifier is not penalised in other areas of the building resulting in a less efficient design.


The success of these details is somewhat reliant on the installation and this is one of the main reasons we provide specific training courses for Sarnafil Registered Contractors and have an experienced Roofing Applications Department who are responsible for training, inspecting and advising on works and carrying out final inspections.

Have another question about detailing, or any other topic relating to single ply? Feel free to send them over and they may well feature in our next FAQ post!