Indian sandstone is a highly sought-after choice for paving due to its versatility, wide array of colours, and durability. Whether you're planning a new garden pathway or a patio, knowing how to lay Indian sandstone correctly is essential to ensure the longevity and aesthetic appeal of your outdoor space. This comprehensive guide will take you through each step of the process, from planning and preparation to the final touches.
1. Setting Out
Before you start digging or ordering materials, take the time to plan your project thoroughly. Visualize how you want your patio or pathway to look. Consider factors like curved edges or a brick border. To gather inspiration, browse online images of other Indian sandstone projects. Once you've settled on the size and shape of your project, mark it out using pegs or spray paint.
Calculate the square meterage of the area you've marked out and add 10% to account for cutting and potential breakages.
2. Buying Your Paving
Selecting the right supplier is crucial when purchasing Indian sandstone paving. To ensure the quality and longevity of your project, choose a reputable supplier. Be cautious of cheaper alternatives from websites selling Indian sandstone from softer sandstone deposits, as these can be porous and prone to staining and damage from freeze-thaw cycles.
Opt for well-known brands such as Marshalls, Bradstone, Pavestone, and Paving Slabs UK for reliability and quality assurance.
3. Working Out Your Levels
Properly setting the levels for your project is essential for both aesthetics and functionality. Determine your finished levels by identifying reference points, such as where your patio meets a sidewalk or the preferred level around your home. Keep in mind that paving around your home should be approximately 150mm (about 6 inches) below the damp proof course.
Establish an optimum level by running a tight string line from your reference points across the patio area. Peg out this level to guide your excavation.
4. Drainage Planning
Effective drainage is a critical consideration for Indian sandstone projects. Ensure that surface water flows away from any nearby buildings and drains efficiently from the paving. Indian sandstone is more absorbent than some other paving materials, making it susceptible to algae growth and becoming slippery in damp conditions.
With your level marked out, you can begin excavating the area. The excavation should reach a depth of approximately 160mm. This depth allows for 20mm for the paving, 40mm for mortar, and 100mm for the sub-base. Take care to create a square and neat excavation with no loose material left behind. Loose soil can lead to settlement and cracked paving.
For removing excavated soil, consider using a skip. Keep in mind that excavated soil increases in volume by about 30% compared to its original state.
Your laying base requires a suitable and compactable sub-base aggregate material. The best choice for this purpose is Mot type 1 compactable aggregate. This material consists of angular particles that compact effectively under pressure. Properly grading the base is crucial to ensure a level mortar bed.
To achieve a consistent mortar bed of around 35mm for easy leveling, peg out your sub-base level 55mm lower than the finished patio level. Use a long spirit level, a tight string line, a hammer, and pegs to establish the sub-base level. Then, spread your sub-base aggregate slightly higher than the top of the pegs at a uniform gradient.
When you compact the base with a whacker plate, it will settle to the top of the pegs, creating a solid foundation for your paving.
Once your sub-base is well-leveled and compacted, you can prepare for laying the paving. Ensure you have ample supplies of sandstone slabs positioned conveniently around the project area. If you're working with different-sized slabs, stack them by size grade to monitor your pattern ratio as you lay the paving.
Organize all necessary materials and tools close to the laying area, taking precautions to prevent cement splatters that can stain the sandstone. Cement stains can be challenging to remove once they set.
8. Mortar Mix
Creating the right mortar mix is crucial for secure and long-lasting adhesion between the sandstone slabs and the sub-base. The recommended mortar mix for laying Indian sandstone is 1 part cement and 4-5 parts sharp sand. Some builders prefer to add 1 part soft sand to this mix, as it enhances workability and stickiness.
The ideal mortar consistency resembles that of thick bricklaying mortar. You should be able to create a wet suction on the mortar with the back of a trowel. This level of moisture content ensures proper adhesion of the sandstone to the mortar.
It's essential to avoid making the mix too powdery or dry, as this can lead to poor bonding and a hollow feeling underfoot.
9. Mortar Thickness
The thickness of your mortar bed is another critical factor. Aim for a mortar bed between 30mm and 40mm. Any less than this, and the bed might be too thin, possibly leading to cracks. Conversely, if the bed is thicker, it becomes challenging to work with and level the slabs effectively.
10. Laying the First Slab
The initial few slabs you lay are perhaps the most crucial part of your project. It's during this phase that you establish the level and falls of your patio or pathway. To maintain precision, keep the edges of your paving square with the lines of your home and any adjacent walls.
Bed down the first Indian sandstone slab and check its falls using a long spirit level. Ensure that the paving sits on a consistent mortar bed with no gaps beneath.
11. Maintaining Joint Consistency
One of the challenges when laying Indian sandstone is maintaining consistent joint widths. Since much of the Indian sandstone available has a rustic finish, some slabs may vary slightly in size and shape. This variation can make it difficult to keep your grouting joints consistently wide.
This challenge becomes more pronounced when you're working with differently sized paving within a pattern. To achieve uniform joints, set out some paving before starting to get a feel for the best joint size. As a general rule of thumb, joints for Indian sandstone paving should be around 10mm wide.
12. Keeping Your Lines Straight
In addition to consistent joints, you must pay attention to keeping your lines straight. The best way to achieve this is by laying your paving back from a perfectly straight feature like a wall. However, be mindful that the further out you build, the greater the chance of wavy joint lines.
As you lay the slabs, regularly check your pattern lines and edges using a string line and a long spirit level.
13. Cap Off Long Joints
If you're working with differently sized Indian sandstone slabs in a pattern, it's important to cap off long joints. Long joints refer to grouting joints that become continuous without being blocked by another slab. As you work, monitor your joints to prevent any of them from becoming excessively long without being capped off.
14. Keeping the Project Clean
Maintaining a clean project site is a crucial factor when laying Indian sandstone paving. You want to prevent mortar splashes and cement stains as much as possible, both on newly laid and previously installed paving. Cement and mortar stains can mar the appearance of your sandstone and are difficult to remove once they set.
When working with paving, it's a good practice to keep a bucket of water and a hand brush nearby. If any cement or mortar splatters onto the paving, promptly wash it off to prevent staining.
Grouting is the final step in the paving process. The best grout mix for Indian sandstone consists of 1 part cement and 3 parts plastering sand. Leighton Buzzard plastering sand is often recommended for its consistent particle size.
The grout mix should be slightly damp, similar to the texture of brown sugar. It should not release any excess cement or water. This consistency allows for precise pointing without staining the sandstone. A well-mixed grout will result in a continuous and dense mortar bed.
For a detailed guide on how to grout paving, refer to our comprehensive step-by-step guide.
16. Sealing (Optional)
While sealing Indian sandstone is not mandatory, it can offer protection against stains and algae growth. Indian sandstone is naturally porous, meaning it can absorb liquids like red wine, coffee, oil, and bird droppings. These substances contain compounds that can stain the paving.
If you anticipate potential staining events, applying a suitable sealant is recommended. Many sealants on the market are specifically designed for Indian sandstone. Selecting the right one can help preserve the appearance and durability of your paving.
Laying Indian sandstone paving correctly is a rewarding but intricate process that requires careful planning, precise execution, and attention to detail. By following the steps outlined in this comprehensive guide, you can create a stunning outdoor space that not only looks beautiful but also withstands the test of time. Whether you're a seasoned DIY enthusiast or embarking on your first paving project, these guidelines will help you achieve professional results and enjoy your Indian sandstone patio or pathway foryears to come.