Chokage of Discharge

Water stagnation due to chokage (at outdoor landscape)

Water stagnation due to chokage (at roof garden)

Design Guidelines

• New gutters should be provided with stainless steel leaf covers, and should be located at or less than 15mm above ground level (SS 525:2006). (See also BS EN 1253-2:2015).
• Locate drains at the edge of landscaped areas [1].
• Drain inlets should be accessible, durable and appropriate for the climate zone [1].
• Adhere to the landscape’s specifications for proper drainage layout and system as per BS 4428:1989.

Construction Guidelines

• Provide eave gutters to maintain fall of 1 in 150 to prevent water ponding and debris build-up. Roof covering should not extend into the gutter, so as to accommodate easy cleaning and maintenance (SS 525:2006). (See also BS EN 1253- 2:2015).
• Maintain construction quality control during the installation of green roof/ green wall components, waterproofing, pipes and fittings, and the planting of vegetation.

Maintenance Guidelines

• Inspect and thoroughly clean rainwater pipe works, gutters and gratings annually (SS 525:2006). (See also BS 7370-5:1998).
• Monitor conditions on a regular basis to head off problems such as insect attacks, disease, or soil problems.
• Long term care requires periodic cleaning and sealing of joints and re-setting of grates and pavement finishes or turf grades due to settlement or silting [1].

References
[1] Harris, C.W. and Dines, N.T. (1998). Time Saver Standards for Landscape Architecture: Design and Construction Data (2nd ed.). USA: McGraw-Hill.

Normative References/Standards Referred to for Drainage 
• BS 4428:1989 — Code of practice for general landscape operations (excluding hard surfaces)
• BS 7370-5:1998 — Grounds maintenance. Recommendations for the maintenance of water areas
• BS EN 1253-2:2015 — Gullies for buildings. Roof drains and floor gullies without trap
• SS 525:2006 — Code of practice for drainage of roofs