How to lay permeable block paving

A step by step GUIDE

Our useful guide can help you if you're a handy DIYer searching for how to lay a permeable block paving driveway. We'll discuss the various materials and tools you'll need as well as the method for creating a driveway that provides a clean aesthetic and drains away water efficiently.

Laying permeable block paving differs from conventional block paving as it allows rainwater to filter through gaps between the blocks into a stone sub-base where there is enough space to store the water for a short time. It can then either soak into the ground or run into drains for reuse.

Laying permeable block paving design considerations

When assessing the design of a permeable paved driveway, thought should be given to levels, soil permeability and soil strength.

Infilta block paving is laid in a similar way to normal block paving. A few key considerations to note for a full infiltration system are:

• Conventional MOT Type 1 is not used for the sub-base as it is not free-draining; we recommend using Bradstone 20mm open-graded Drainage Aggregate.
• Don't allow vehicles to run on the sub-base during construction, as they will cause rutting in the loose surface.
• A free-draining 6mm bedding aggregate is laid in place of normal bedding sand.
• Permeable blocks are restrained with a kerb or edging that provides more than adequate support to traffic.
• A suitable geotextile is a compulsory requirement below the drainage aggregate sub-base.
• To ensure better drainage performance, a second layer of the geotextile can be laid between the drainage aggregate and the bedding aggregate.

How to lay permeable block paving: Step-by-step guide

STEP 1 

Excavate and prepare the underlying ground to a suitable depth above the level of the water table. Any low points should be filled and compacted with a Type 3 material, such as crushed granite or limestone. The finished height of the driveway should be a minimum of two courses below any damp-proof course in surrounding structures.

STEP 2 

Install a haunched kerb to the sides that are not already edged. The haunch to the front of the kerb should be a minimum of 25mm below the finished level of the base of the paving. Leave a gap between the kerb and the block for filling with jointing aggregate when completed.

STEP 3 

Lay a suitable geotextile membrane to the base and sides of the area to be laid. Any joints must be overlapped by a minimum of 300mm.

STEP 4 

The depth of the subbase will be governed by the strength and type of the underlying ground. Typically, you will need to be around 200mm deep on soils of good strength and 500mm in areas of poor soil strength. Add in compacted layers not exceeding 150mm at a time.

STEP 5 

The laying course uses Bradstone Bedding Aggregate, a 6mm angular, open-graded material. The laying course should be 50mm thick and does not need to be compacted before the blocks are then laid. Once the blocks are laid, and before jointing, a light pass over with a whacker plate and rubber mat is required.

STEP 6

Bradstone 3mm Jointing Aggregate is used for joint filling. Brush in and ensure there is no loose aggregate on the surface that could mark the blocks before another pass with the whacker. Finally, brush in more aggregate to fill any gaps as required.

Hire an installer to lay permeable paving blocks

If you don't have the time to do it yourself, we can also help you find Bradstone-assured installers in your area who specialise in how to lay permeable block paving.

Installers are likely able to complete the driveway quicker and may have greater manpower. The biggest benefit of having a permeable block paving fitted by an installer is that your driveway will be backed by the Bradstone Assured Guarantee.

Get help from Bradstone

Ready to make a start on laying a permeable block paving driveway? Use our handy questionnaire to find the right paving for your project or order some free samples if you want to assess your options up close and personal.

Find your nearest Bradstone stockist when you know what you want. If you need any further assistance, contact us or read more of our helpful guides.

STEP 9 CLEAN AND CLEAR

It's good practice to immediately wipe down the paving slab using clean water and a sponge, looking out for any slurry primer that may have fallen onto the face. This should be removed immediately as it won't come off once set. 

Remember to clear enough mortar from the gaps between the pavers to allow sufficient jointing compound to sit comfortably. Follow the manufacturer's installation instructions to check the application and suitability. A dry application method must not be used when laying heavily textured natural stone paving as it is prone to staining.

If cutting is required, you'll need a suitable specification of blade along with a water input for dust suppression. You must wear all relevant PPE during this stage.

Lastly, dress the patio… and enjoy!