While the environmental benefits of SuDS are clear, there are practical reasons to consider them for small house extensions. The main reason is compliance with planning regulations. Over the past couple of years, we have noticed a trend that Local Planning Authorities are asking for SuDS to be considered on more and more small-scale developments.

We understand that there is nothing more frustrating than a planning application being refused or delayed because SuDS/surface water drainage has not been considered. By incorporating SuDS at the earliest possible time during the planning phase of the project, it can streamline the approval process.

For small house extensions, you don’t need a large budget or space to implement SuDS effectively. Some effective and affordable options can include:

• Permeable Paving: By replacing conventional hard surfaces like driveways or patios with permeable materials, it can allow rainwater to soak through rather than running off into a drain. Flow controls and additional storage within the sub-base can also be incorporated into the design depending on the requirements.
• Rain Gardens: A rain garden is a shallow, landscaped area that captures and absorbs rainwater from roof downpipes, driveways, or other impervious surfaces. By utilising native planting, it is possible to create an attractive space in a garden with biodiversity benefits.
• Water butts: A simple and cost-effective way to collect and store rainwater from your roof. The rainwater collected can be used for tasks such as watering plants, cleaning patios or washing your car, saving on your water bills. Slow-release water butts are specially designed to collect rainwater from roofs and downpipes. They store large amounts of water during heavy rainfall, gradually and sustainably releasing the water after storms have passed, alleviating strain on the drainage system including surface water sewers.
• Green roofs: If your extension has a flat or low-pitched roof, consider installing a green roof. There are a wide range of benefits outside of the obvious stormwater management and environmental benefits. Green roofs can reduce heat loss in winter and limit heat gain in summer, lowering energy bills. They also tick the SuDS box, making it easier to gain planning approval.
• Planters: Disconnecting/rerouting a rainwater downpipe to drain into a raised planter can significantly reduce the overall runoff from the site. Integrated SuDS planters come with storage, flow controls and overflows built in.

By integrating features like permeable paving, rain gardens, water butts, planters and green roofs into your design, you can protect the environment, enhance your property, and (most importantly) achieve planning at the first time of asking.

In some areas, the ground conditions may comprise of clay or another soil with poor permeability, which are not conducive to soakaways or other infiltration SuDS. In fact, installing a soakaway into an area with poor soakage characteristics can have the opposite effect as intended, where gardens can become waterlogged and boggy during winter months.

In accordance with British Standards, soakaways must be positioned at least 5m away from any buildings and at least 2.5m from property boundaries and underground utilities. This can be challenging to achieve in small gardens.