Darren Crane, National Sales Manager – Buying Groups and Independent Merchants at ACO Water Management, at ACO Water Management, outlines the key considerations for effective driveway drainage.
The role of the driveway has changed significantly over the last 12 months. Lockdown has seen an increase in delivery services – which often relies on heavy vehicles – and home improvement projects have become more important as people spend time at home. As such, driveways face more pressure to withstand added load, perform water management duties, and to be aesthetically pleasing.
Covid-19 and the subsequent lockdowns have triggered a home-improvements boom in the UK. An estimated 3 in 5 homeowners carried out a DIY or renovation project during the first lockdown, and research suggests this is a trend that is going to continue. This is hardly surprising, with people spending more time than ever in their homes, and as the gateway to the house, attention is increasingly turning to upgrading driveways.
Coming in all shapes and sizes, the approach to managing surface water on a driveway can often depend on the materials used as part of its construction. While there is no one-size-fits-all approach to drainage, there are a number of common factors that contractors should consider when approaching a project.
Load class
Driveways are subject to a range of different stresses, which makes getting the right load class of drainage channel an absolute priority. It isn’t just a case of specifying drainage channels according to the weight of the homeowner’s vehicle, as there are a range of other, heavier vehicles that are likely to use it. Lockdown has seen more of us take advantage of home deliveries, meaning vans and other HGVs may come into contact with the channel – especially if it is adjacent to the road or footpath.
The speed and direction that a vehicle drives over the channel is also a factor and should be reflected in the load bearing capabilities. For example, if the driveway is on a slope, vehicles may be turning faster and at a different angle compared to one that is on a flat level. It is important to plan for the maximum load a channel may have to bear.
In response to the issues outlined above, B 125 drainage channels are recommended as a minimum for driveways, offering the appropriate load bearing capabilities for the types of stresses a typical driveway is likely to experience. ACO Water Management’s RainDrain® B 125 channels are an example of a B 125 channel that interlock for quick and easy installation and are available in grated and Brickslot options.
Working with extensions
Research from Santander has highlighted that over 60,000 home planning applications were submitted in the first UK lockdown, which if completed would add more than 1.5 million square metres of space to housing stock. It is important for contractors to recognise that in any extension, whether this is a car park, paved area, or indeed a driveway, you’re making the surface area larger. This means that you are required to manage a greater quantity of surface water, often more than the original system was designed to handle.
In these circumstances, measures should be taken to reduce the burden on the original system. One of the ways in which this can be done is to let the water permeate straight into the ground, using a permeable surface such as ACO GroundGuard. This is a 90 per cent porous material that provides effective drainage of surface water when installed with a type 3 installation and saves on unnecessary drainage installation. If non-permeable materials are being used as part of the extension, an attenuation tank or rain garden may be required.
Positioned to save
Depending on where drainage channels are located, they will require varying degrees of robustness. For example, if they are placed along the side of the driveway, rather than the driveway threshold, there may be less chance of heavy vehicles or machinery putting pressure on them.
This can be useful for value engineering, as lighter grade lower cost channels can be purchased if they will be bearing less weight. However, it is important to consider the factors we have mentioned so far, and to ensure the driveway is appropriately cambered to take rainfall into the channels.
Keep the garage dry
A lot of driveways are accompanied by a garage, and many people wouldn’t consider drainage in front of the garage door unless the driveway fell towards it. However, consideration should be given to the amount of water around the junction at the foot of a garage door, as they are likely to be subject to higher volumes of rainfall.
This is because any rain that hits the façade of the garage will run down it and add to the water landing directly on the drive, effectively increasing the water volume that is required to be removed. If the driveway does camber towards the garage, it is worth considering an ‘intercept’ style grating, so that even in heavy rainfall the water won’t bridge the grate to penetrate the garage.
Where will it go?
It’s important to remember that it’s not just about collecting rainfall, but discharging it to somewhere appropriate, and not just allowing it to pool wherever it naturally flows. This may sound obvious, but it is a frequent design flaw that we’ve encountered on driveways.
Special measures may be required on non-permeable driveways, with ACO’s versatile Stormbrixx an ideal stormwater management system for attenuation and soakaway infiltration usage.
Each and every driveway is different, and it is crucial to adopt a case-by-case approach. ACO Water Management has many tools and training options, which are free to use, and capable of offering bespoke advice for water management.
For more help and to get in touch with ACO visit https://www.aco.co.uk/drive_entrance
