There is no limit on the height to which the single ply membrane can be bonded up a flat roof upstand. As long as the 150mm minimum upstand height is achieved then theoretically the upstand can extend to any height to suit the roof design and roof edge detail.

Practical considerations, however, are likely to have more of a say than what is theoretically possible. Handling the single ply membrane for a large upstand is difficult, and the contact adhesives used to secure the membrane in position are only active for a certain length of time.

What are the potential issues of bonding a large flat roof upstand?

These practical considerations might necessitate installing the upstand membrane in smaller sections, which is time consuming and may not achieve the desired aesthetics.

It is also worth considering that many upstands are insulated to help address linear thermal bridging. For cost reasons, it may not be desirable for the insulation to extend as far as the upstand membrane, which could create a step in the detail that must also be waterproofed carefully and neatly.

A comprehensive overview of upstands is given in a separate blog post. Alternatively, for more information about detailing, contact our technical services team to discuss your next project.

For more information, please contact IKO Polymeric’s technical team.