Permeable Block Paving for driveways - your complete how-to guide
Have you ever pulled into your driveway on a rainy day to find it waterlogged and failing to drain? Don't accept drenched socks – permeable brick and block paving promotes natural drainage and keeps your driveway safe and smooth in all types of weather – without the need for planning permission.
Here's everything you need to know about permeable solutions for your driveway – from planning to paving.
Concrete Block Permeable Paving (CBPP) differs from conventional block paving because it allows water to soak through the driveway, preventing water from amassing and flooding. This is laid on top of a sub-base which allows water to be stored and pass through while still allowing driving and parking.
How to Lay Permeable Block Paving
The installation of our Infilta range varies slightly from standard block paving, but remains simple and intuitive. We'll walk you through the steps:
Please note the below guidance is applicable to domestic driveways for car traffic only.
When assessing the design of your permeable paved driveway, consider the finished height levels, soil permeability and soil strength.
Once you're ready, it's time to lay the sub-base. Conventional MOT Type 1 is not suitable for the sub-base as it is not free draining. Instead, the open graded Bradstone 20mm Drainage Aggregate will be used in this walkthrough.
For free draining application, a suitable geotextile should be placed at formation level (overlapping joints by 300mm), below the 20mm Drainage Aggregate sub-base. When the sub-base is designed to hold water, an impermeable membrane lining should be used.
The depth of the sub-base will be determined by the strength and type of the underlying ground. Typically, you will need a depth of around 200mm deep on soils of good strength and 500mm in areas of poor soil strength.
Avoid running vehicles on the sub-base during construction if possible. This will potentially cause rutting in the loose surface. The blocks will be restrained in the conventional way with a kerb or edging, which provides more than adequate support to traffic.
Laying sub-base with Bradstone 20mm Drainage Aggregate
The laying course uses Bradstone Bedding Aggregate, a 6mm angular, open graded material.
Unlike normal bedding sand, the aggregate is free draining – no need for you to continually monitor moisture content.
The laying course should be 50mm thick, rather than 30mm for conventional paving and is not compacted before the blocks are laid.
Once laid, and prior to jointing, perform a light pass over with a whacker plate and rubber mat.
The preparation and levelling of the bedding surface is critical – an aggregate bedding layer will not be compacted as it would with conventional block paving.
Brushing in Bradstone 3mm Jointing Aggregate
Bradstone Infilta blocks have a nominal joint width of 5mm, which is greater than a normal block paving. Therefore, the Bradstone 3mm Jointing Aggregate is the best choice for joint filling.
- Ensure there is no loose aggregate on the surface that could mark the blocks
- Brush in the aggregate.
- Pass over with the whacker and rubber mat as required.
- Brush in more aggregate to fill the remaining voids.
Compacting blocks with wacker plate
Do I need planning permission?
If the surface to be covered is more than five square metres, you will need planning permission for laying traditional, impermeable driveways that do not control rainwater running off onto roads. This will apply to new driveways, drive extensions or drive replacements.
You won't need planning permission if:
- Your new driveway is permeable or porous.
- The surface to be covered is less than five square metres.
- If it is directed to a soakaway via a drainage channel. An estimated 70% of existing driveways already drain in a sustainable way.
What other factors need to be considered?
Slopes. The driveway should be sloped away from the house wherever possible towards the road. Do not direct water into rain gardens or soakaways close to buildings.
Underground services. Make sure there are no underground services close to the ground surface where you are paving (e.g. water pipes, cable TV, electricity cables, etc).
Contaminated sites. If you live on a site that was contaminated by previous uses the shallow soils may have been specifically designed to prevent water soaking into the ground. If this is the case, you will have to connect the paved area to the drains.
Soil type. The soil below the driveway must be sandy or gravelly (not clay) otherwise a connection to the drains may be required. This can be checked by a simple test.
If you want more advice, we can help. Simply Paving is here to support every stage of your landscaping project. For advice, assistance, or inspiration, give us a call on 0800 032 6306. We would love to hear from you.