Mon, 20th May, 2024

Guaranteeing patio paving slabs involves several meticulous steps. Start by measuring and marking the designated area accurately. Excavate to a depth of 200mm and lay a compacted sub-base of 150mm. Prepare a 50mm concrete mix mortar bed before positioning the paving slabs. Tap each slab into place with a rubber mallet for a thorough fit. Seal natural stone and concrete slabs to enhance durability and aesthetics.

Essential tools include a spirit level, disc grinder, and hammer, while necessary materials comprise paving slabs, sub-base aggregate, and grout. For a thorough approach, guarantee precise measurements and alignment. Explore further for detailed techniques and tips.


Key Takeaways

  • Measure and mark the patio area accurately before starting excavation.
  • Excavate the area uniformly to a depth of 200mm.
  • Lay a 150mm compacted sub-base for a stable foundation.
  • Prepare a 50mm deep concrete mix mortar bed for laying the slabs.
  • Seal natural stone and concrete slabs to enhance durability and appearance.



This guide offers comprehensive instructions for installing various types of patio paving slabs, including porcelain, natural stone, and concrete.

Each material has unique characteristics that may influence the installation process, but the fundamental steps remain consistent.


Guide suitable for all types of patio paving slabs

Laying patio paving slabs, whether they are porcelain, natural stone, or concrete, requires careful planning and execution to ensure a long-lasting and visually appealing outdoor area.

This guide offers general steps suitable for all types, including preparing the sub-base, laying the mortar bed, and jointing techniques.

Choosing the right materials and maintaining them properly will further enhance the durability and attractiveness of your patio, creating a sense of pride and ownership.


Porcelain Paving Slabs

Porcelain paving slabs offer a durable, low-maintenance solution for outdoor spaces, combining resistance to staining, frost, and fading with a modern aesthetic.

These slabs are:

  1. Non-porous: Easy to clean and maintain.

  2. Versatile: Available in various sizes, colours, and finishes.

  3. Durable: Long-lasting and ideal for high-traffic areas.

  4. Aesthetic: Mimic natural stone, wood, or concrete for a contemporary look.


Natural Stone Paving Slabs (Sandstone, Limestone, Slate & Granite)

Natural stone paving slabs have become a popular choice for outdoor spaces due to their distinct aesthetic and functional benefits. Sandstone, limestone, slate, and granite are some of the commonly used options. Sandstone stands out for its diverse colours and textures, making it suitable for any design. Limestone is known for its durability and weather resistance, making it ideal for high-traffic areas. Slate, on the other hand, offers a sleek and modern appeal with its textured surface. Granite is renowned for its strength, making it perfect for areas with heavy footfall.

These natural stone options provide a wide range of choices to cater to different preferences and practical needs in outdoor design. Each type offers unique characteristics that can enhance the overall look and functionality of outdoor spaces, adding value and beauty to landscaping projects.


Concrete Paving Slabs

Concrete paving slabs provide a durable and cost-effective solution for patios and other outdoor spaces. Their versatility and ease of installation make them a popular choice.

Here are four key benefits:

  1. Durability: Long-lasting and resistant to weather conditions.

  2. Low Maintenance: Requires minimal upkeep.

  3. Variety: Available in various sizes, shapes, and colours.

  4. Cost-Effective: Affordable without compromising quality.


The Primary Steps

The primary steps in laying patio paving slabs begin with accurately measuring and marking out the designated area.

This is followed by excavating the site to a depth of 200mm and installing a compacted sub-base of 150mm.


Measure and mark out your patio area

To start your patio project, accurately measure the patio area in square metres to determine the quantity of materials required.

Mark out the patio area on the ground using the following steps:

  1. Use wooden pegs and string for alignment.

  2. Transfer your plan to the ground with a builder's square.

  3. Mark lines on pegs for working layer depths.

  4. Ensure a slight slope for proper drainage.


Excavate the patio area (200mm depth)

Begin by excavating the patio area to a uniform depth of 200mm, ensuring the removal of all debris and vegetation to create a stable foundation.

This depth allows for proper sub-base preparation and long-lasting stability. Use a spade or mini digger for even excavation, and regularly check the depth throughout the process to maintain consistency and confirm the foundation is ready for the next steps.


Install the sub-base (compacted & 150mm depth)

With the patio area excavated to the required depth, proceed to install a 150mm compacted sub-base to ensure stability and durability.

Follow these steps:

  1. Spread MOT Type 1 aggregate evenly across the area.

  2. Utilise a plate compactor to thoroughly compact the sub-base.

  3. Check for level and adjust if necessary.

  4. Ensure adequate drainage to prevent water pooling.

This foundation ensures long-term performance and cohesion in your patio project.


Prepare a concrete mix mortar bed (50mm depth)

Establish a stable and durable foundation for your patio by preparing a concrete mix mortar bed with a precise depth of 50mm.

This mortar bed guarantees a strong bond between the paving slabs and the sub-base, preventing movement or sinking.


Lay the paving slabs on the mortar bed and tamp down

Aligning with the paving guidelines, place each paving slab onto the prepared mortar bed and gently tap down using a rubber mallet.

Ensure accuracy by following these steps:

  1. Position slabs: Align each slab with the string lines.

  2. Tap gently: Use a rubber mallet to tap down each slab.

  3. Check levels: Use a spirit level to ensure evenness.

  4. Maintain consistency: Keep a uniform 1cm gap between slabs.


Ensure proper joint spacing between slabs

Accurate joint spacing between paving slabs is vital to maintain the structural integrity and aesthetic appeal of your patio. Maintain a consistent joint spacing of 10-15mm by using wooden spacers or offcuts. This guarantees necessary expansion and contraction, enhancing both durability and appearance.

Evenly spaced joints create a neat, professional finish, fostering a sense of belonging in your outdoor space.


Ensure slabs are 'level' to the fall

Ensuring the paving slabs are level to the fall is essential for effective drainage and the long-term durability of your patio.

Follow these steps:

  1. Check alignment using a spirit level.

  2. Set the fall to approximately 1:80 for optimal water runoff.

  3. Prevent water pooling by maintaining a consistent slope.

  4. Regularly check levels across all slabs to guarantee uniformity and functionality.


Allow the mortar bed to set for 24 hours

Allowing the mortar bed to cure for at least 24 hours is essential to guarantee the stability and longevity of your patio paving slabs. This period ensures proper bonding and maximum strength, preventing displacement and shifting.

Avoid walking or placing heavy loads on the slabs during this time. Patience during the curing process will ultimately result in a durable and long-lasting patio installation.


Fill the joints between the paving with pointing

Filling the joints between the paving slabs with pointing is essential for the structural integrity and aesthetic finish of your patio.


Follow these steps:

  1. Mix mortar: Use 4 parts building sand to 1 part cement, ensuring a slightly moist consistency.

  2. Apply mortar: Firmly press it into the gaps with a trowel.

  3. Clean slabs: Wipe excess mortar with a damp sponge.

  4. Curing time: Allow 24 hours to dry before use.


Additional Steps (depending on paving slab material)

When laying patio paving slabs, additional steps may be required based on the material used. For natural stone and concrete slabs, sealing is recommended to protect against stains and weathering.

In some cases, particularly for black stone, applying a stain or sealer can enhance the appearance and longevity of the paving.


Seal the flags (natural stone and concrete flags)

Sealing natural stone and concrete slabs is an important step to enhance appearance and extend the longevity of your patio.

  1. Protection Against Stains: Use a natural finish sealer for stone and a colour-enhancing sealer for concrete.

  2. Water Resistance: Prevents water absorption and potential damage.

  3. Colour Enhancement: Enriches the material's natural hues.

  4. Longevity: Follow manufacturer guidelines for best application and reapplication intervals.


Stain/seal the slabs (black stone sealer)

Applying a black stone sealer to your paving slabs can greatly enhance their colour and appearance while providing essential long-term protection against stains and weather-related damage. This sealing process is vital for preventing moisture penetration, frost damage, and efflorescence.

Make sure you follow the manufacturer's recommendations for the appropriate sealer and application method to achieve best results, prolonging the lifespan of your patio.


List of essential tools 

A well-prepared toolkit is crucial for ensuring the successful installation of patio paving slabs. Key tools include:

  1. Spirit level - To achieve a perfectly level surface.

  2. Rubber mallet - To tap slabs into place without causing damage.

  3. Disc grinder or hammer and chisel - For precise cutting of slabs.

  4. Plywood - To maintain consistent joint spacing during installation.

This toolkit ensures precision and quality in your patio project. Check out our full range of hand tools here.


List of essential materials

Essential materials for laying patio paving slabs include:

  • Paving slabs
  • Sub-base aggregate
  • Cement
  • Sharp sand
  • Jointing compound or grout.



Detailed Instructions

In this section, we will provide detailed instructions starting with measuring and marking out your patio area, ensuring accurate placement of the paving slabs.

Next, we will guide you through calculating the square metres (m²) required and determining the necessary amount of paving, including an additional contingency.


Measuring and marking out the patio area

When measuring and marking out the patio area, it is essential to ensure accuracy in square metres to determine the precise amount of materials required.

Follow these steps:

  1. Transfer the patio plan using wooden pegs, builders square, and string.

  2. Mark lines on pegs to indicate the working layer depths.

  3. Ensure alignment with existing paving and manhole covers.

  4. Allow for a slope away from the house for drainage.


Calculating the square metres (m²) of the paving area

After measuring and marking out the patio area with precision, the next step is to calculate the square metres (m²) of the paving area to guarantee adequate material procurement.

Measure the length and width of the designated area in metres, then multiply these dimensions.

This calculation assures you have the correct quantity of paving slabs, aiding in cost estimation and efficient project planning.


Determining the amount of paving needed (including contingency)

Accurately determining the amount of paving needed, including a contingency buffer, is vital to guarantee a seamless and efficient installation process.

Follow these steps:

  1. Measure the patio area: Multiply the length by the width.

  2. Calculate slab quantity: Divide the patio area by the area of a single slab.

  3. Add a 10% contingency: Account for cuts and breakages.

  4. Consider layout: Make sure alignment with your design pattern.


Calculating material quantities

Calculating the necessary quantities of materials for your patio project is the next critical step to ensure you have everything required for a smooth installation.

Begin by determining the total square meterage of your patio area. Estimate the number of paving slabs needed, account for a 10% contingency, and calculate the required bedding mortar and jointing compound.

Make sure you purchase extra materials to accommodate potential breakages or mistakes.


Sub-base (DTp1 Hardcore/MOT Type 1) - 150mm depth, compacted

For the stability and load-bearing capacity of your patio to be guaranteed, the sub-base should consist of DTp1 hardcore or MOT Type 1 aggregate with a recommended depth of 150mm.

Follow these steps:

  1. Spread the aggregate evenly.
  2. Compact the material using a plate compactor.
  3. Check for level and adjust as necessary.
  4. Ensure uniform compaction to prevent sinking.

Proper preparation fosters a durable patio foundation.


Mortar bed (5:1 sharp sand and cement) - 50mm depth

With the sub-base firmly in place, the next step involves preparing a mortar bed using a 5:1 mixture of sharp sand and cement to a depth of 50mm. Ensure the mortar bed is evenly spread and compacted, creating a stable and level base for the slabs.

Use a trowel to achieve a smooth, consistent surface, supporting the slabs' weight and ensuring long-term stability.



In conclusion, ensuring a well-prepared sub-base and meticulously following each step of the patio paving process will result in a durable and aesthetically pleasing outdoor space.

Remember these key points:

  1. Preparation: A solid sub-base is essential.

  2. Laying: Use a full mortar bed for stability.

  3. Jointing: Secure slabs with proper compounds.

  4. Sealing: Protect and enhance your patio's appearance.

Frequently Asked Questions

How Do You Lay Paving Slabs for Beginners?

To lay paving slabs for beginners, measure and mark the area, prepare a solid sub-base, mix and apply a mortar bed, carefully position the slabs, and fill gaps with mortar. Allow 24 hours for curing.

Can You Lay Paving Slabs Directly Onto Soil?

Laying paving slabs directly onto soil is not advised due to possible issues such as uneven settling and instability. A stable, level sub-base, like DTp1 hardcore, is essential to ensure the longevity and durability of your patio.

What to Put Under Patio Slabs?

For a stable foundation, place a compacted sub-base of MOT Type 1 Hardcore, followed by a layer of sharp sand. Optionally, use a geotextile membrane beneath the sub-base to enhance drainage and prevent weed growth.

Do I Need to Leave a Gap Between Paving Slabs?

Yes, it is essential to leave a gap between paving slabs, usually around 10-15mm, to accommodate expansion and contraction caused by temperature changes, aid water drainage, and improve the patio's durability and appearance.