Permeable Pavers Installation Guide
Permeable Pavers Installation
Our Premier Hydropavers® are the perfect choice for architects, builders and DIY fanatics who want to turn their hardscaped areas into environmentally-friendly spaces.
Here is general installation guide.
It is vital that a thorough site investigation be completed. During the site investigation the soil type needs to be determined and an infiltration test completed to establish the drainage characteristics of the soil. This can be done by using a two ring apparatus or by conducting a visual/tactile assessment of the soil. There are three types of Permeable Paving Systems: •
- System A. Total infiltration.
- System B. Partial infiltration.
- System C. Water harvesting.
It is also important that the strength of the soil be determined. For small projects the soil can be categorised in the following ways:
- Strong: Sandy loams.
- Average: Silty loams.
- Weak: Clay soils.
If infiltration rates are too low, as per System B, slotted pipes need to be installed at the formation level to remove excess water. In situations where there is significant fall on the area, the excavation may need to be stepped to assist in the infiltration of the water into the sub-grade.
The traffic loads of the designated area also have to be determined in regard to the type of traffic and the frequency.
Subbase and base construction
There is a direct correlation between the amount of fines in the crushed rock and the strength of the base. But in general terms there is an average of 25% porosity within the base material. This equates to being able to store 250 L of water per 1 m³ of base.
The base course material should be spread and compacted in layers. The thickness of these layers must be consistent with the compaction capacity of the equipment being used. It is recommended that a vibrating roller be used for no fines base materials.
Base levelling and surface finish
The surface of the base needs to be levelled and finished to a + or – 2mm tolerance from predetermined design levels
Geotextile materials can be used to great effect as separation layers. It is recommended the fabric be placed between the base course and the bedding material or between the subgrade and the base course.
The bedding material used for PPS is not a traditional bedding sand. It needs to be a no fines 2-3mm course sand or gravel. Alternately the material commonly known as quarter minus, an imperial measurement, which is a 4 to 6 mm crushed stone can be used. It is recommended that on large projects engineering specifications be obtained or at a minimum the manufacturer be consulted.
The bedding sand needs to be installed to a uniform 30 mm thickness with a +/-2 mm tolerance. The material needs to be lightly compacted using a vibrating plate compactor or non-vibrating heavy roller. It is important that once the bedding material has been installed and screeded that it not be disturbed.
Paver laying techniques
The pavers can now be laid to the selected pattern. The pattern of the paving needs to be decided based on what application the paving is being used for. The three main categories of patterns are:
- Herringbone – 45° and 90° herringbone
- Parquetry – Parquetry – basket weave, half basket weave
- Stretcher – stack bond and stretcher bond
The area needs to be set out so that all string lines are 90° angles. It is imperative when using a square or rectangular paver that this be achieved.
The pavers are laid directly on the bedding material as in any other flexible paving system. It is important when laying the pavers that no paver be 2 mm higher than any adjacent paver. On completion of laying full pavers the cut pavers need to be installed. It is essential that when cutting pavers that all occupational health and safety requirements be strictly followed. It is also essential that the pavers be cut using a diamond blade saw.
Joint filling and post laying compaction
The fine graded washed sand needs to be totally dry so it will flow into the joints more easily and not bridge between adjacent pavers. For ease of installation sand is recommended as the ideal jointing material as it creates better interlock, as allowing water to enter via the joints is not a priority.
Once the joints have been filled, it is essential to compact the pavers using a vibrating plate with a rubber mat attachment. This process will ensure that all the joints are thoroughly filled, to create maximum interlock, and that the pavers are properly levelled and all lipping is eliminated.
All paved areas should be provided with edge restraints to prevent lateral spread of the pavers and consequent loss of interlock. The design and size of this edge restraint is dependent on the traffic loads applied to the pavement.
For vehicular traffic it is highly recommended that the edge restraint be concrete and preferably with some form of steel reinforcing.
On pedestrian areas treated timber or galvanised steel may be more appropriate.
Due to the nature of the no fines material used in permeable paving systems it is recommended that the concrete edge restraint be installed before laying commences.
Please note that the guide is for general knowledge only. The permeability of the complete paving depends on the sub-base and sub-grade structure. We advise you to have professional input before commencing the construction.
If you need help, we do have a team of landscapers that can assist you.
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