A Guide for Landscapers: Common Misconceptions for Threshold Drainage Installation
There exists a pervasive misconception perpetuated by certain drain suppliers and embraced by landscapers, which suggests that a straightforward uniflow channel drain can be installed at the junction where the external paving meets the door threshold and the internal building structure. This assumption asserts that such drains can be fitted at any level, regardless of the existing DPCs/DPMs. However, it is crucial to clarify that this notion is incorrect and poses a significant risk.
Moreover, there is a common misunderstanding regarding Part M building regulations and disabled access. It is important to note that these regulations do not govern the installation, integration, or construction of drainage at the aforementioned junction. Their sole purpose is to ensure the presence of a level surface, facilitating wheelchair movement.
The height at which the top of the drain cover (level) is set in relation to the internal and external levels directly influences the necessity for meticulous detailing and enhancement of the DPC barriers, both horizontally and vertically. Furthermore, selecting the appropriate drain for this location becomes paramount.
When dealing with a stepped threshold, a simple uniflow channel drain can be employed to collect water from the paved surfaces surrounding the drain. However, in the case of a flush level, or nearly flush door threshold, it is imperative to utilise a dualflow drain. This type of drain collects water from two sources: the paved area and, more importantly, the water that exits the fenestration/door track system through the weep holes or the bullnose threshold.
It is essential to highlight that if a simple uniflow drain is used instead of a dualflow drain system in this specific location, the individual responsible will be held liable for any resulting damage. This holds true regardless of whether a signed waiver is in place or not.
Companies that claim simple channel drains can be utilised at this location, irrespective of its name, for flush level access requirements are misleading and fail to fully elucidate the actuality and consequences of such a choice. They rely on the limited knowledge of landscapers regarding the precise reasons why a drain is necessary in relation to the building's structure.
We hope this information proves beneficial to all landscapers.