Marshalls Guide to Laying Priora Permeable Paving
Instructions common to all Priora Driveway Products featured
- Each 60mm block features the Marshalls unique patented ‘Priora’ nib design which allows surface water to pass between blocks into a specially calculated sub-base without compromising the structural performance of the driveway
- Drains water away safely in heavy rainfall without becoming a burden to the local drainage system
- Can help preserve the local water table by rehydrating ground prone to droughts
- If installed with the correct sub-base this permeable paving solution can be used in a front garden without obtaining planning permission
Priora IMPORTANT Installation Note
The Priora System should not be attempted by the DIY enthusiast or untrained installer. It requires the careful calculation of a soil permeability test and appropriate use of specially graded sub-base aggregates.**
Should an installer wish to undertake training for the installation of this product please call the Marshalls Helpline on 0345 820 5000 for further information. Visit the Marshalls website to find your nearest Marshalls Register Installers trained to install Priora Systems, or call 0345 820 5000.
- Drivesett Tegula Priora blocks are designed to be laid in a coursed laying pattern (supplied in packs). Ratio per square metre; 3 small, 12 medium, 16 large.
- Drivesett Argent Priora blocks are designed to be laid in a coursed laying pattern (supplied in pack).
- Supplied in mixed packs of 3 sizes meaning less wastage and potential cost savings.
- Driveline Priora is supplied in single size packs and can be laid in herringbone.
Conditions Required For Priora
The grade of Priora featured in this brochure is only intended for normal domestic vehicles and pedestrian traffic, though occasional delivery vehicles over 3.5 tonnes gross weight can be tolerated.*
The Domestic Priora System is only intended for driveways or paths where infiltration is required only in the immediate Priora paved area and not from other surrounding paved or roofed areas (see rainwater catchment area guideline opposite). In some parts of the country there are ground conditions where infiltration could adversely affect foundations to houses, therefore, if in doubt seek advice from a specialist or the local authority building control department. Properties constructed pre 1920 may not have been built on traditional concrete foundation, therefore in this case, Marshalls Domestic Priora System should not be installed. Check for services, Priora must not be installed if gas or electric services run through intended Priora areas. ®Priora is a trademark of UNI-International Bausysteme GmbH
Guidelines For Installing Priora
The intended Priora area must fall away from the owner’s house and any other buildings in the immediate vicinity. If the driveway exceeds 20m in length and/or has a gradient greater than 1 in 100 then please contact Marshalls Technical Advisory Service.* The top surface of the driveway should finish at least 150mm below any adjoining wall DPC level.
If your house lies adjacent to or less than 600mm from the proposed Domestic Priora driveway area, establish depth of house foundation before undertaking any soil test/Priora installation. The house foundation top surface must be 600mm (minimum) below the finished level of the top of the proposed Priora driveway.
Soil Strength and Permeability
Marshalls Domestic Priora System must be laid on a subgrade which has previously had an established and adequate existing driveway and an area which has a subgrade soil strength greater than 5%. The Domestic Priora System is only suitable for soil areas where infiltration applies and the test criteria have been met as per the standard permeability test. For the standard permeability a test hole should be dug for every 20m2 of driveway. There should be a minimum of two holes. Holes/pits should be spaced evenly in relation to the proposed Priora area.*
Discharge onto Roadway
The Domestic Priora area must not discharge onto surrounding public roadway and pathways and towards any buildings.
Rainwater Catchment Area
No adjoining surface areas (rainwater pipes, roof areas, etc) must drain onto and into the proposed Domestic Priora driveway area, however, small areas such as door steps and garage areas are acceptable providing they do not exceed 5% of the driveway area. Guideline: Catchment area **= driveway area **Catchment area = drained surface area
Priora must be laid with 20mm and 6mm clean crushed stone aggregate to BS EN13242 and BS EN12620 to ensure compliance. Priora must be laid with 20mm and 6mm clean crushed stone aggregate to BS EN13242 and BS EN12620 to ensure compliance. When installing in close proximity to existing trees, tree roots smaller than 25mm diameter may be pruned back, preferably to a side branch, using a suitable pair of secateurs or hand saw. Roots larger than 25mm should only be severed following consultation with an arboriculturist, as they may be essential to the tree’s health and stability. Protection of the pavement will also be required, hence the requirement of a permeable root barrier systemr which is non surface protruding, and therefore, does not present a trip hazard once installed.
Health and Safety
It is possible that more excavation for a Priora driveway may be required than that of a driveway constructed of traditional block paving, therefore, care must be taken when excavating ground to a deeper level. Particular care must be taken to protect the sites from children and partially sighted persons and for collapse of adjoining features such as boundary walls/fences.
Check for services, if they run through intended Priora areas, the service provider must be consulted before work commences. Care must be taken when constructing over sewer, rainwater pipes and water pipes to ensure that the services remain supported for their full length by undisturbed material and are surrounded on the remaining sides by a minimum of 150mm of 6mm material to protect the service.