Understanding balcony drainage strategy and methods – Whitepaper

What is the best balcony drainage method?

This balcony drainage whitepaper is intended to give an overview of the design philosophy behind the Sapphire drainage options, as an aid to correct specification.

What is the difference between controlled drainage versus positive drainage?

Traditionally, roofs and the like in excess of 6m2 have been required to have positive drainage, primarily due to the accumulation of water runoff at one point, which can provide nuisance and lead to pattern staining.

Positive drainage has also lead to a crisis in New Zealand. The leaky homes crisis in New Zealand was estimated in 2009 to have incurred costs of approximately $11.3 billion and is still ongoing. This construction and legal crisis affected timber-framed buildings built from 1994 – 2004 which suffered from issues with their weather-tightness and drainage.

Over the past decade, Sapphire have pioneered the concept of dividing the soffits on longer balconies into smaller sections so the runoff is evenly dispersed along the length of the balcony. This design has been successfully adopted in many projects throughout UK and Ireland, in projects up to 30 stories.

The concept has also been endorsed by the BS 8579 committee and incorporated in the new standard for balconies of any length, and up to 2500 mm projection.

The reasons for publishing this whitepaper are:

1. Disjointed legislation and multiple other parties stipulating certain requirements making it tricky to work out what is permissible and what is not.
2. Specifiers not understanding the difference between integral waterproofing and a sperate method leading to confusion.
3. Balconies often being mistakenly classified as adding to the water load, as it was unclear how to accurately work out the drainage discharge.

Within this paper we will also explore the drainage options for balconies and key considerations to be aware of when specifying.

Download the drainage whitepaper to continue reading.