A step by step guide on how to prepare the ground and lay Infilta Block Paving including tools required and tips for success from our friends over at Bradstone.
Concrete block permeable paving differs from conventional block paving as it allows rainwater to filter through gaps between the blocks into a stone sub base below where there is enough space to store the water for a short time. It can then either soak into the ground or into drains to collect the water for reuse.
When assessing the design of a permeable paved driveway considerations should be given to levels, soil permeability and soil strength.
- Conventional MOT Type 1 is not used for the sub base as it is not free draining, the Bradstone 20mm open graded Drainage Aggregate is used.
- It is best to prevent vehicles running on the sub base during construction if possible, as they will cause rutting in the loose surface.
- Once the blocks are laid it is restrained in the conventional way with a kerb or edging and provides more than adequate support to traffic.
- In free draining applications, a suitable geotextile should be placed at formation level (overlapping joints by 300mm), below the drainage aggregate subbase.
- Where the subbase is designed to hold water an impermeable membrane lining should be used.
STEP 1: 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.
STEP 2: The laying course uses Bradstone Bedding Aggregate, a 6mm angular, open graded material. Unlike normal bedding sand, it is free draining and therefore it does not require any control on moisture content.
- The laying course should be 50mm thick, rather than 30mm for conventional paving and it is not compacted before the blocks are laid.
- Once laid, and prior to jointing, a light pass over with a whacker plate with a rubber mat is required.
STEP 3: Bradstone Infilta blocks have a nominal joint width of 5mm which is greater than normal block paving.
STEP 4: Bradstone 3mm Jointing Aggregate should be used for joint filling. Brush in and after ensuring there is not loose aggregate on the surface that could mark the blocks, another pass with the whacker is required.
- Finally, brush in more aggregate to fill voids as required.
- The preparation and levelling of the bedding surface is critical as an aggregate bedding layer will not be compacted as with conventional block paving.
- The above guidance applies to driveways for domestic car traffic only.
- The laying of permeable surfaces using Bradstone Infilta block paving should follow the guidance in BS7533 Part 3.
- Bradstone recommend that permeable paved driveways should only be laid by trained, competent installers.
Why not download the Bradstone Laying Infilta Block Paving Guide to take on site: