Choosing the Right Paving: Selecting Materials That Last
Choosing a paving product is about much more than appearance. While colour, texture and style all influence the finished look of a project, the size, thickness, strength and installation method of the paving units are equally important. Selecting the wrong product for the intended use can lead to cracking, breakage, movement and premature failure.
British Standard BS 7533 sets out guidance on the suitability of different paving materials for different applications. For domestic patios, driveways and pathways, this means considering not only the paving itself, but also how it will be installed, how it will be supported, and the type of traffic it will experience during its life.
Start with the Intended Use
One of the first questions to ask is how the paved area will be used.
A pedestrian-only garden path places very different demands on paving compared with a driveway that regularly carries cars and vans. The required paving thickness, foundation design and construction method all depend on the loading the pavement will experience.
For domestic projects, typical applications include:
- Garden paths.
- Patios and seating areas.
- Parking spaces.
- Domestic driveways.
- Shared access routes.
The paving selected should always be appropriate for the expected traffic and loading conditions.
Choose a Surface That Remains Safe
Slip resistance is an important but sometimes overlooked consideration.
External paving needs to remain safe in wet weather, particularly in areas regularly used by pedestrians. As paving surfaces age, some materials can become smoother through wear, especially where large numbers of people pass over the same routes.
When selecting paving materials, avoid products that become excessively polished in service, such as some limestones. In busy public areas this is particularly important, but even domestic installations benefit from choosing paving that maintains good grip throughout the year. Textured concrete products, clay pavers, riven stone and many sawn natural stone finishes typically perform well when correctly specified.
Understand the Different Paving Options
Modern paving projects commonly use one of five material types:
Concrete Flags
Concrete flags are available in a wide range of sizes and finishes and remain one of the most popular choices for patios and pathways.
They offer good durability, consistent dimensions and predictable performance when installed correctly. Larger flags generally require greater care during handling and installation, particularly where vehicle loading is involved.
Natural Stone Slabs
Natural stone provides a premium appearance and significant design flexibility.
However, not all stone performs in the same way. Flexural strength, water absorption, weather resistance and abrasion resistance can vary considerably between stone types. British Standard guidance highlights the importance of understanding these properties when selecting natural stone, particularly for heavily used areas.
Where stone strength information is unavailable, a more conservative approach should be adopted when assessing thickness requirements.
Concrete Block Paving
Concrete block paving is commonly used on driveways and areas requiring unbound construction.
Its strength comes not only from the blocks themselves but also from the interlock created in the joints between units and the quality of the supporting layers beneath. The choice of laying pattern plays an important role in long-term performance.
Clay Pavers
Clay paving offers excellent durability, colour stability and a traditional appearance.
Because clay products are fired rather than coloured during manufacture, their appearance remains consistent even after years of use. Clay pavers are suitable for both bound and unbound paving systems when installed using appropriate construction methods.
Clay pavers are more durable than concrete due to their density, low water absorption and resistance to wear.
Porcelain Paving
Porcelain paving has become increasingly popular because of its contemporary appearance, low water absorption and durability.
Unlike concrete or natural stone, porcelain should generally be installed using bound construction techniques. Its strength allows relatively thin units to be used, provided the foundation layer, appropriate bedding and bonding methods are followed. This includes the correct aggregate for the bedding mortar, with the preference being igneous 2/6 mm at a 1-4 ratio.
Size and Thickness Matter
Larger paving units are not automatically stronger.
As paving units increase in length and width, they can become more susceptible to loading and bending forces unless thickness is increased accordingly. For this reason, BS 7533 places limits on the dimensions and proportions of paving units used in domestic applications.
As a general principle:
- Larger units normally require greater thickness.
- Vehicle traffic usually requires thicker paving than pedestrian-only use.
- Different materials have different strength characteristics.
- Bound construction often allows thinner paving than unbound construction.
The relationship between unit size, thickness and construction type should always be considered as part of the overall pavement design.
Pay Attention to Joint Widths
The spacing between paving units is more important than many people realise.
Joint widths in unbound paving are one of the details can decide whether a pavement succeeds or fails. BS 7533 sets them out plainly for unbound construction: 2–5 mm for concrete blocks, 3–6 mm for clay pavers, 2–5 mm for sawn stone slabs and concrete flags, 6–12 mm for stone slabs with fettled edges, and 0–10 mm or 0–15 mm for cropped stone setts under over 100 mm wide respectively — with cropped setts sitting in point contact with their neighbours, so the “joint” is really the void between irregular faces. Nibs and joint spacers can override the minimums where a wider, more stable joint is needed. Knibs should not be relied upon.
For bound construction, a mortar‑filled joint should be no less than 5 mm wide, with 6–10 mm the working range in practice: wide enough for a slurry‑applied jointing mortar to flow and key into the full depth of the unit. Never exceeding 25mm in width and only in the instance of rough heavily textured/cropped sides.
Joints are not simply aesthetic features. They help accommodate manufacturing tolerances, prevent edge damage and play a key role in pavement performance.
For unbound paving, excessively narrow joints can make it difficult to achieve proper interlock and joint filling. Excessively wide joints may affect appearance and durability.
Typical joint widths vary depending on the paving type:
- Block paving generally uses narrow joints.
- Clay pavers require slightly larger joints.
- Natural stone setts often require wider or more variable joints.
- Bound paving with mortar-filled joints generally requires wider joints than unbound systems.
Paving units should not normally be laid tightly against each other unless specifically designed for that purpose.
Consider the Whole Construction, Not Just the Surface
The visible paving is only one part of the finished pavement.
BS 7533 emphasises that the overall construction depth includes:
- The paving unit itself.
- The laying course or bedding layer.
- The base layer.
- Any sub-base required beneath.
Selecting beautiful paving without providing adequate foundations underneath is one of the most common causes of failure in domestic paving projects.
The paving, bedding, base and sub-base should all work together as a complete system.
Bound or Unbound?
Most domestic paving falls into one of two installation methods.
Unbound Construction
In unbound construction, paving units are laid on type1/type 3 sub-base/base, sand bedding material and joints are filled with kiln dried sand or 2-6mm for permeable installation . Noting in permeable installation, 2-6mm is used for the laying course.
Common examples include:
- Block paving driveways.
- Clay paver driveways.
- Some natural stone sett installations.
Bound Construction
In bound construction has two main installation methods, paving units are either laid bound over unbound and on mortar beds and joints are filled with cementious grouts. Or on the preferred option a reinforced concrete slab.
Examples include:
- Porcelain patios.
- Most modern natural stone patios.
- Many concrete paving slab installations.
Bound paving generally provides a stiffer pavement structure and often supports thinner paving units than would be suitable in an unbound system.
Choosing the Right Product from the Start
The most successful paving projects begin with selecting products that are suitable for the intended use and installation method.
Appearance remains important, but durability, dimensions, slip resistance, strength and compatibility with the chosen construction method are equally critical. By considering these factors before installation begins, landscapers can create paved surfaces that not only look attractive on completion but continue to perform reliably for many years to come.
