Natural Paving Guide to Laying Natural Stone Block Paving
Planning permission is not required if the rain water from the paved area does not run onto the public highway or discharge directly into the surface water drainage system. All paving and surfacing, whether it’s new work, replacement, or extension, is subject to legislation, so even if you are only replacing your existing surfacing with products from Natural Paving, the work will have to be installed in accordance with the regulations.
Do you have to use permeable paving? - NO – If the surface is permitted to drain to a permeable or porous area located within the grounds of the property. The easiest and most cost effective solution is to drain all rain water onto gardens or borders if suitable. If the existing paved area currently does so and there are no problems, then carry out a straight forward replacement of the old material.
If the proposed area is significantly redesigned then consider draining rain water with falls and/or line drainage to rain gardens or soakaways. NB soakaways must be 5m from any property. Size of rain garden needs to be 10% of paved area.
There are design criteria for rain gardens but simply creating a depression at the back of a lawn for which rain water can collect and percolate through the soil is sufficient. This can be a flower bed or gravel area if suitabl
Laying Natural Stone Block Paving
All block paving, whether it’s a patio, a driveway requires at least three layers: a sub-base to give it strength; a laying course of sharp sand to support the blocks; and the paving blocks themselves. It also needs to have firm edges to hold the paving securely in place.
The sub-base should be at least 150mm deep for driveways and 100mm for patios. The laying course should be approximately 40mm. Taking into account the thickness of the block excavate to the required level ensuring you are 150mm below DPC of any adjacent building. It’s often a good idea to hire a mini-digger or a larger excavator with an experienced operator to undertake this task. Diggers are also useful for loading spoil and spreading the sub-base material. When excavating be careful of any services under the area to be worked.Edge restraints hold the paving firmly in place and prevent it ‘spreading’. Where the paving lies against a wall, this can act as the edge restraint, but elsewhere a restraining edge will need to be constructed. This may be a kerb or simply a course of paving blocks laid on concrete. Set up a taut string line and use this as a guide to both line and level while laying the edge course. Mix concrete for the bed and haunch using 6 parts all-in ballast with 1 part cement. Add just enough water to bind together the dry ingredients. Place the edge course units onto a bed of concrete approximately 100-125mm deep and tap down to level using a rubber mallet. When a kerb is used, it’s a good idea to lay the kerb and the edge blocks in one operation. All restraining edge courses must be haunched by placing concrete at the back and packing it down. Haunching should cover roughly two-thirds of the unit and be at least 100mm wide. Remember: these edge courses are supporting and restraining the rest of the paving so it is essential that they are firmly constructed.
The next task is to spread, level and compact the sub-base material. Free draining material such as crushed stone known as “Type 1” is recommended to form the sub-base. The sub-base should be thoroughly compacted. Level out the sub-base material to create a finished profile which matches that intended for the paving. It’s vital that the next layer, the laying course, has a regular, uniform thickness, so the sub-base needs to be accurate to around 10mm. Check the level and add or remove material as required to create a reasonably accurate profile. The laying course is formed by ‘screeding’ a damp coarse sharp sand to the required level. Building or masonry sand is not suitable and will cause the finished paving to settle. Spread and level a layer of sharp sand roughly 50-55mm thick. Pass over he sand once or twice with the plate compactor to partially compact. Use a length of straight timber to scrape off the top of the sand layer, reducing its level in the process and creating a smooth, even surface, approximately 40mm thick, on which to lay the paving blocks. You may need various lengths of timber and a float trowel to prepare the laying course. It should be borne in mind that the final profile of this laying course will be the same as that of the finished paving, so it is worth spending time getting it right. The finished screed should leave the blocks 5-8mm high so they can be compacted downwards when laid. Lightly loosen the sand surface with a fine rake to allow for an even level after compaction.
Avoid walking on the screeded laying course, always work ‘uphill’, and choose a starting point that is a straight edge or a right- angle corner. As natural stone varies in colour and texture ensure you have enough product on site to complete the project and always mix the product from all the packs during installation. This will minimise the effect of colour banding. Place each block carefully onto the laying course. To avoid spawling and/or chipping of the blocks, a gap of 2-5mm is recommended. In order to make the laying of the blocks with a gap easier, we suggest using pre-formed spacers. Try to place the blocks straight down onto the bed so that sand isn’t trapped in the joints. Once blocks have been laid, they can be walked upon with care, but try to keep back from the leading edge. Lay all the full blocks first. Blocks to “piece-in” can be cut using a hired-in block splitter or disc cutter. Avoid very small cuts that are less than one-third the size of a full block. Instead, cut two blocks, each being more than half-a-block, and use these to fill the gap.
Once cutting-in is completed, the paving is jointed by sweeping kiln-dried sand over the surface to fill the joints ensuring they are completely filled. The blocks are compacted with four to six passes with a plate compactor, changing the direction of pass as much as possible. Consideration should be given to the use of a rubber or neoprene mat attached to the underside of the plate compactor. This will minimise damage to the surface of the blocks. Check the area for any damaged blocks and replace them. Add more kiln-dried sand if required or sweep any excess sand into a corner and then make another pass or two with the plate compactor to settle the sand into the joints. The surplus sand is used to top-up those joints that appear partially empty.
And that’s it; your new natural stone block paving driveway can be used immediately. Over the first few weeks, the jointing sand may settle further and if this happens, the joints should be topped-up with additional sand.
Whilst our block paving is laid in a similar way to concrete block paving, more care should be afforded when laying natural stone to ensure the desired finish is achieved.