# How to Lay Indian Sandstone Paving: Step-by-Step UK Guide **By YUKAI WANG** ยท 2026-06-22 Indian sandstone paving should be laid on a stable, well-compacted sub-base and a continuous full mortar bed. The back of every slab should be clean and coated with a suitable priming slurry before it is placed. Correct falls, full bedding and properly filled joints are more important to the long-term result than laying the slabs quickly. This guide explains the standard method used for a domestic UK patio. Ground conditions, drainage requirements and structural loading vary, so seek professional advice where the site includes unstable ground, major retaining work, vehicle traffic or drainage close to a building. ## What You Need ### Materials - [Indian sandstone paving slabs](/collections/sandstone-paving "Indian sandstone paving slabs") - MOT Type 1 sub-base material - Sharp or coarse washed sand - Cement - Natural stone priming slurry, or a suitable SBR and cement slurry where specified - A compatible exterior paving jointing compound or pointing mortar - Geotextile membrane where ground conditions require separation or additional stability ### Tools and safety equipment - Tape measure, pegs, string line and spirit level - Shovel, rake, wheelbarrow and pointing trowel - Plate compactor - Cement mixer or suitable mixing equipment - White rubber mallet - Stiff brush, soft broom, sponge and clean water - Angle grinder or wet saw with a suitable diamond blade - Gloves, eye protection, hearing protection and suitable respiratory protection Cutting sandstone and handling cement-based products can create hazardous dust. Follow the equipment manufacturer's instructions and current HSE guidance, control dust and wear the correct personal protective equipment. ## 1\. Inspect and Blend the Paving Indian sandstone is a natural, split stone. Colour, surface texture, thickness and hand-cut dimensions can vary from slab to slab. This variation is part of the material rather than a manufacturing fault. Open all packs before laying and select slabs from several crates as the work progresses. Spread lighter, darker and more strongly patterned pieces across the patio instead of completing one pack at a time. Check each slab for transit damage and decide where the strongest colour variations and feature pieces will sit. For a mixed-size patio pack, study the intended layout before mixing mortar. A loose trial arrangement can help, but retain the planned joint widths and do not assume every hand-cut slab will be dimensionally identical. ## 2\. Mark the Patio and Establish the Fall Mark the finished perimeter with pegs and tight string lines. Check rectangular areas by measuring both diagonals. The diagonals should match if the setting-out is square. The paving must drain away from buildings and must not direct water towards neighbouring property or an unsuitable part of the garden. A fall of approximately 1:60 is commonly used for natural stone patios. This equals about 17 mm of drop per metre. Site conditions may require a different design, particularly around thresholds, retaining walls and channel drains. Where paving meets a house, the finished surface should normally remain at least 150 mm below the damp-proof course unless a properly designed alternative detail is used. Plan drainage before excavation, not after the slabs have been laid. ## 3\. Excavate to the Required Depth For a typical pedestrian patio, excavation often needs to accommodate: - Approximately 100 mm of compacted MOT Type 1 - Approximately 30-40 mm of bedding mortar - The actual thickness of the sandstone paving This commonly produces a total excavation depth of roughly 150-170 mm below the intended finished level, but the correct depth depends on slab thickness, ground strength and drainage design. Remove topsoil, organic matter and all soft spots. The formation should be firm and stable before the sub-base is installed. A geotextile membrane can be used where it is necessary to separate the sub-grade from the sub-base. It does not replace proper excavation or compaction. ## 4\. Install and Compact the Sub-Base Spread MOT Type 1 in layers rather than tipping the full depth at once. For a 100 mm finished sub-base, place and compact it in two layers of around 50 mm. Pass a plate compactor repeatedly over each layer, including edges and corners, then check the levels against the string lines before adding the next layer. The finished sub-base should be dense, stable and shaped to follow the planned drainage fall. Poor compaction is one of the main causes of settlement, rocking slabs and failed joints. ## 5\. Prepare the Bedding Mortar A common bedding mix for Indian sandstone is four or five parts sharp sand to one part cement. Local sands differ, so the exact water demand and working consistency will vary. The mortar should be moist and workable, holding its shape when spread. An overly wet mix allows slabs to move and sink; a dry, crumbly mix will not compact or bond properly. Spread enough mortar for one slab at a time and form a continuous bed, usually around 30-40 mm thick before final tapping. Slightly ridge the surface so the mortar can compress evenly beneath the stone. Do not use isolated mortar spots, rings or a dot-and-dab method. Voids beneath sandstone can collect water, reduce support, cause rocking and contribute to staining or frost-related failure. ## 6\. Clean and Prime Every Slab Dust from splitting, calibration, transport and site cutting can prevent a reliable bond. Brush or wash the underside of each slab and allow excess water to drain. The back must be clean before priming. Apply a proprietary natural stone priming slurry across the complete underside, including the edges of the back face. Where an installer uses an SBR and cement slurry, it must be mixed and applied in accordance with the relevant product instructions. Lay the slab while the primer is still wet and active. Keep slurry off the visible face and exposed edges. Remove accidental marks immediately with clean water and a sponge or brush; once cementitious residue hardens, it can be difficult to remove without affecting the stone. ## 7\. Lay the First Slab Carefully The first slab establishes the level and fall for the surrounding paving. Lower the primed slab onto the fresh full mortar bed and tap it gently with a white rubber mallet. Use the string line as the principal guide and check across neighbouring positions with a straightedge or spirit level. Riven sandstone has natural high and low points, so a spirit level placed directly on the textured face can rock. Judge the intended laying plane and water flow rather than trying to make every natural ridge touch the level. If the slab is too high, lift it, remove some mortar and relay it. If it is too low, lift it and add mortar across the bed. Do not repeatedly hammer a slab into a thin or hollow bed. ## 8\. Continue Laying and Maintain the Joints Continue one slab at a time, maintaining the string-line fall and blending material from different packs. Indian sandstone is normally laid with visible joints rather than butt-jointed. For hand-cut paving, joints of roughly 10-15 mm are common because they accommodate small dimensional variations while retaining a traditional appearance. Calibrated or sawn products may suit a different joint width. Check the chosen jointing product before fixing the layout because every system has minimum joint-width and depth requirements. Remove bedding mortar that rises into the joint while it is fresh. The joint needs adequate clear depth for the pointing material to perform correctly. Clean the face of the paving continuously. Cement, slurry and dirty water should not be allowed to dry on sandstone. ## 9\. Cut Edge Slabs Safely Lay as many full slabs as practical before measuring the perimeter cuts. Measure each opening separately and allow for the joint on both sides. Mark a clear cutting line and support the slab on a stable, non-rocking surface. Use a suitable diamond blade and dust-control method. Let the blade perform the cutting without excessive force. Cut edges are best placed against an edging, wall or less prominent boundary where the layout permits. ## 10\. Allow the Bedding to Cure Protect the newly laid patio from foot traffic, heavy rain, frost and rapid drying. Do not begin jointing until the slabs and bedding are sufficiently firm. A minimum wait of about 24 hours is common in suitable conditions, but colder or wetter weather can require longer. Follow the mortar and jointing-product manufacturers' instructions. ## 11\. Point or Joint the Patio Before jointing, remove loose mortar, dust and debris from the full joint depth. Confirm that the paving and joints meet the moisture conditions required by the selected product. Common options include traditional sand-and-cement pointing, ready-mixed brush-in compounds, two-part resin products and flowable cement-based grouts. These systems are not interchangeable: - **Traditional mortar:** offers a conventional finish but requires careful placement, compaction and cleaning. - **Brush-in compound:** is convenient for many domestic patios, but minimum joint dimensions, moisture and curing conditions must be followed. - **Two-part resin:** can provide a stronger joint where correctly mixed and compacted. - **Flowable cement grout:** can fill joints quickly but requires controlled timing, thorough cleaning and protection of drains. Do not wash cement-based grout into surface-water drains. Work in manageable areas and clean residue before it bonds to the stone. When sweeping a brush-in product, work diagonally across the joints so the material is not pulled back out. ## 12\. Final Cleaning and Optional Sealing After the jointing material has cured, inspect the patio for cement haze, loose residue and blocked drainage outlets. Use a cleaner specifically approved for sandstone if treatment is required. Avoid strong acidic cleaners, which can damage stone and pointing. Sealing Indian sandstone is optional rather than compulsory. If a sealer is chosen, the paving must be clean, dry and sufficiently weathered for residual moisture and salts to escape. Use a breathable product suitable for exterior sandstone and test it on an inconspicuous area first. Sealing too early can trap moisture or alter the appearance unevenly. ## Alternative: Laying Over a Concrete Base A sound concrete slab can sometimes form the structural base for sandstone paving, particularly where excavation depth is restricted or the project has been specifically designed that way. The concrete must be stable, properly cured, free of contamination and laid or detailed to manage water. Cracks, movement joints and drainage require careful assessment. Sandstone should still be installed on a compatible continuous bedding system with the back of each slab primed. A concrete base is not automatically superior and should not be poured simply to compensate for weak preparation. Trapping water between impermeable layers can create long-term problems if drainage is poorly designed. ## Common Installation Mistakes Mistake Likely result Correct approach Insufficient excavation or compaction Settlement, rocking and cracked joints Remove soft ground and compact MOT Type 1 in layers No planned drainage fall Standing water and damp problems Set levels and drainage before laying Spot bedding Voids, weak support and possible staining Use a continuous full mortar bed Failing to prime the slabs Paving can debond from the mortar Clean and prime the complete underside Laying one crate at a time Concentrated patches of colour Blend slabs from all available packs Butt-jointing hand-cut slabs Irregular alignment and weak or unfillable joints Maintain a practical, consistent joint width Leaving cement on the surface Haze, staining and difficult cleaning Clean continuously with fresh water ## FAQs About Laying Indian Sandstone Paving ### Can Indian sandstone be laid directly onto soil? No. Soil does not provide the stable, evenly supported base required for a permanent patio. A properly prepared and compacted sub-base and a full mortar bed are normally required. ### How deep should the sub-base be? A domestic pedestrian patio commonly uses around 100 mm of compacted MOT Type 1. Weak ground, raised construction or heavier loading may require a site-specific design and greater depth. ### What mortar mix should be used for Indian sandstone? A mix of approximately four or five parts sharp sand to one part cement is widely used. It should form a workable, moist bedding mortar rather than a runny mix. Material and site conditions can affect the final specification. ### Does every sandstone slab need priming? Yes. Cleaning and priming the full underside of every slab greatly improves adhesion between the stone and the mortar bed. Water alone is not equivalent to a proprietary bonding slurry. ### Can Indian sandstone be laid using dot and dab mortar? No. Indian sandstone should be continuously supported on a full mortar bed. Spot bedding leaves voids that can weaken the installation and retain water. ### What joint width is suitable for Indian sandstone? Hand-cut Indian sandstone commonly uses joints of around 10-15 mm, although the correct width depends on the product, dimensional tolerance, layout and chosen pointing system. ### How long should sandstone paving be left before pointing? About 24 hours is a common minimum in favourable conditions, but the bedding may need longer in cool or wet weather. The slabs must be firm enough to walk on without movement, and the jointing manufacturer's curing instructions take priority. ### Should Indian sandstone be sealed after installation? Sealing is optional. It can help with stain management, especially on smoother finishes, but the paving must be clean and thoroughly dry. Use a breathable exterior natural-stone sealer and test the appearance before treating the whole patio. ## Buying the Right Sandstone for the Project Accurate product information makes installation easier. Check whether the paving is calibrated, the stated nominal thickness, the pack layout and the expected dimensional tolerances before ordering. Allow for cuts, breakage and site selection rather than buying only the exact measured area. Paving Slabs Direct supplies Indian sandstone through a direct, cost-efficient import and distribution model. This gives homeowners, landscapers and contractors access to practical UK paving specifications without unnecessary layers in the supply chain. Explore our [sandstone paving range](/collections/sandstone-paving "Sandstone paving slabs") when planning your patio. --- > Source: [Paving Slabs Direct](https://www.pavingslabsdirect.co.uk/blogs/sandstone-paving-advice/how-to-lay-indian-sandstone-paving-uk-guide)