Buildings; Apartments, Houses

Sustainable Drainage Systems provide practical solutions for managing surface water in apartment blocks and shared accomodation buildings. SuDS must be included in this scale of building design as it offers both environmental and social benefits and complies with the Ebbsleet Garden City SuDS requirements.

When considering the application of SuDS to apartment buildings and houses the following interventions offer practical additions to the start of the SuDS chain.

Rainwater harvesting

ALL buildings provide an opportunity to provide the first priority in the SuDS hierarchy, "collected for non-potable use". This can include domestic uses in a shared water sytem and irrigation for areas of biodiversity in communal spaces and green roofs.

Green Roofs

A highly effective option on apartment blocks as they can be included alongside solar panels and othe roof based structures. By incorporating vegetation layers on rooftops, rainfall is intercepted and gradually released, reducing peak runoff rates. Green roofs also improve thermal performance, enhance biodiversity, and contribute to urban cooling. They can be applied to main roof structures and ancillary buildings, providing flexible opportunities for water management. Smaller green roofs can be incorporated on permanent structures such as cycle storage, bin stores and other small scale structures.

Above Ground Attenuation Planters

These represent another valuable addition to the SuDS train and are an easily included SuDS intervention. Large scale planters can provide areas for Biodiversity Net Gain and sustainable drainage in the same space utilising water from building run off to irrigate and slow the flow of surface water.

The new National Standards for SuDS does not include simple water butts as an approved intervention and these should not be considered for inclusion in schemes to meet SuDS requirements.

These measures demonstrate how SuDS can be scaled to apartment buildings, delivering resilience against flooding while improving local amenity. Their adoption supports wider sustainability goals and helps communities adapt to increasing rainfall intensity linked to climate change.

On plot; Front Gardens, Driveways, Paving Bays

At the plot scale, there are opportunities to further slow the flow of surface water utilising all the suitable surfaces within the plot.

Permeable Paving

A minimum of 15 m² of paved surfaces must be permeable in design, with capacity for rainwater storage within the sub-base. Surface material can be permeable block or resin bound gravel but the sub-base must be designed with surface water storage intrinsic to the specification. These systems utilise geocellular products or recycled materials to create voids that create space for below ground level attenuation.

RAIN GARDENS

Planted areas can be designed as rain gardens or filter strips, both of which will slow the water from the building onto the streetscape. The front garden defensible space contains planted areas that can accomodate a preparatory SuDS element and still be attractively planted with plants suitable for a rain garden.

FILTER STRIPS

Filter strips which add to the plot's ability to add to the SuDS train can be included as dividers between driveways or other slightly sloping vegetated spaces.

As surface water from plot areas generally runs onto the street, the opportunity to slow this additional water before it reaches the streetscape is a vital part of the continuous SuDS train.

COMPACTION

One of the most common issues raised in complaints to developers is excessive surface water within plots. This is frequently caused by compaction of subsoil layers and the correct preparation of plot soil profiles and the inclusion of the right SuDS interventions can help to decrease this common issue.

In larger scale communal plots around apartments and shared spaces, there are opportunities to include permeable paths, SuDS enabled tree pits and larger rain gardens to increase the area of SuDS interventions.

Communal parking bays and visitor spaces should all be specified and installed as permeable paving.

Streets

There are three categories of streets that are covered in this guidance:

• Residential Distributors

• Residential Streets

• Homezones and Mews

The specific requirements for the streetscape is set out in the SuDS SELECTOR SCORING FRAMEWORK section as follows:

Minimum Selection Rules for Street & Neighbourhood

For every 50m street section, a developer must:

1. Select any two or more SuDS features that together score ≥19 points.

2. Ensure ≥50% of street trees are SuDS-enabled.

3. Meet minimum size/depth/soil-volume standards.

If a combination does not meet all three, it is non-compliant.