How do you lay a stone patio?

Answer 1

* Sketch the proposed patio. * Show the dimensions.

* Show the layout of stones if there is to be a set pattern.

* Decide from where you will need to start laying the stones. This may be a critical edge, such as aligning with a building or existing path, or a central point in circular paving. If more than one edge is critical you will need to start from both at once and gradually move inwards.

* Decide where any cut stones will be less noticeable. It is best to not have small cut stones at a prominent edge, such as a doorway where you will notice them as you walk across. For regular shaped, such as rectangular or square stones, a good place for a line of stones that need to be cut smaller may be may be along one less prominent edge. For less regular laying patterns it may be best to have smaller stones at irregular points rather than all in one place where they will draw attention. For a circular or curved pattern, smaller stones may work well at the centre or on the inside of curves. * Calculate a sufficient slope to allow the stone surface to drain.This may be a 1% fall or 1:100 or 1:200. It will depend on the use of the patio, the amount of rain and the smoothness of the stones.

* Ensure the direction of drainage is away from adjacent buildings. * Calculate the required area of stone. * If you will need to allow for cutting stone, allow for at least 20% wastage, possibly more depending on the layout and type of stone. * Check what loads will be going onto the patio. If vehicles will drive across it it will have different requirements, including depth of excavation and hard fill/base course and the thickness and type of paving stone. Get advice from suppliers as to the suitability of the stone. * Calculate the depth and therefore the volume of hard fill required to go under the pavers. This is gravel with a mix of stones from a set size and smaller down to fines or sand. Having a mix of sizes makes it compact and form a stable surface. For pedestrian use only the hard fill will need to be to a depth of at least 150mm, for vehicle use at least 300mm. If the soil or subsoil is soft you may need to excavate deeper to ensure a stable base. It should extend least 200mm beyond the paved area to make the edges stable. * Calculate the required volume of bedding sand. Bedding sand is sharp sand and gives a firm and stable base after wetting. It will go on top of the hard fill and under the paving stones. It gives a smooth even surface for the paving to sit on and covers any sharp pointed stones in the hard fill that might put pressure on a paving stone and cause it to crack when stood on. The sand layer will need to be at least 50mmm deep, and if the stones you are laying are of a variable thickness it may need to be deeper. If it is too deep the paving will not be as stable. * Check the drainage of the area and allow for field drains to divert water if the area is prone to waterlogging or has subsurface flow. * Select and purchase stone, hard fill, bedding sand, drainage material etc. Arrange for heavy stone to be delivered if possible. The supplier may allow you to bring back any unused stone: check this before purchasing. * Gather all required tools and materials. * Mark the area to be paved. * Check the dimensions and squareness if it is rectangular or square by checking that the diagonals are the same length. * Hammer in temporary pegs and set up string level lines about 1m outside the area to be paved. This allows you to check that the fill and paving are at the right heights as you work. Use a string level that clips onto the string, or a spirit level or a laser level. You will measure down from the string so do not forget to allow the extra distance that the string is above the ground to your measurements. * For large areas of paving or areas adjacent to soft soil or gardens it can be a good idea to construct an edge strip to stop the paving fromn sinking towards the soft area. This can be constructed from ground treated timber pegs hammered in to about 30mm below what will be the finished paved surface and then with metal, plastic or timber fixed to them with galvanised flat head nails and set flush with or about 5mm below what will be the finished paved surface. If there are curves along the edge, use thinner timber or plastic that can be bent to follow the curve.

* Excavate the area to be paved to the depth required which will be the hard fill depth plus the sand depth plus the depth of the paving stones.

* Excavate any required drains and ensure they have an outflow. This may need to comply with local regulations.

* Cut back any tree roots projecting into the excavated area, but not so much that this will kill trees or make them unstable. If major roots intrude, you will need specialist advice regarding cutting them back, or you may need to accept that the paving will shift over time as the tree grows. * You may wish to lay a geotextile to reduce the penetration of dirt into the hard fill. This is a fabric underlay. This is more useful in areas to be gravelled, but can also help with reducing root penetration and add stability. Check with local paving suppliers as to what they would recommend for your soil, patio type and other conditions. * Lay any drainage material in the excavated trenches. (Pea gravel, slotted pipe etc.) * Lay hardfill/base course to the excavated area. Check the required depth against the string lines and compact a small area. Check the depth of this area after compacting and add or remove material as required. Compact all the fill. For very small areas stomping or tamping with a big piece of wood may be adequate, for larger areas, or areas that will take heavy loads it is worth hiring a compactor. A plate compactor is best for large areas. * Check the height and correct any high or low points more than 10-20mm away from the desired level. * Lay the bedding sand. Rake it out evenly and check the depth and height. * Set out pavers in a handy location, and sort if necessary, by size or colour. Some pavers may need to be mixed up so that you do not work from one load and find after laying that it was a slighly different colour to the next, resulting in a patchy looking patio. If there are slight variations it is best to randomly mix them to avoid this. * For irregular stone pavers, set aside ones that have straight edges for edge use, and small stones for infilling. * Set up any required cutting tools so that you can cut as you go.

* Begin placing the stones from critical points you decided earlier. This includes edges formed with edging strips.

* Lay a single stone at a time and place it carefully onto the sand while holding it flat so that it does not dig into the sand and create a low point. For larger pavers this may require two people. * Tap the paver lightly with a rubber mallet to bed it into the sand. * Check it is level, or at the required angle for drainage, and tap again as required. If it is not, you may need to lift it and remove or add a little sand. * Proceed with laying the adjacent pavers in the same way. Check each paver is aligned with the adjacent pavers. Work back and forth in rows or around in curves, or out from a central point. * For regular shaped pavers butt pavers tightly. For irregular pavers allow a minimum 5mm gap between paver. * Frequently step back and check from several viewpoints that you are following the correct slope and that your work is even. Be prepared to lift pavers that are not correct. * Scatter further bedding sand over the paved area and sweep with a soft broom so that it falls into the gaps. Repeat until the gaps are filled. * Wet the area lightly to bed the sand in. * Add more sand and repeat the sweeping and wetting. * Back fill the 200mm strip around the pavers (and outside the edge strip if you have used one) with a little more hard fill up to about 50mm below the pavers, and compact this. It will help to keep the pavers in position. Lay soil over this, if the area adjacent is garden, or grass if lawn.

* Do not walk heavily or drive on this area until all gaps are well filled and the bedding sand compacted, or the pavers may tilt and shift.