Interior and finishes · Tiles & Stone
Natural Stone Setts and Cobbles (Paving Units)
Describes setts and cobbles as deep external paving units and separates them from thin natural stone tiling, leaving the build-up, bedding and jointing to the qualified professional designing the paved area.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What stone setts is
Setts are small, deep paving units cut or split from hard stone, most often granites and other durable igneous and metamorphic rocks, and supplied as cubes or as short rectangles. Cobbles, strictly speaking, are rounded stones used more or less as found rather than cut units, although in everyday conversation about paving the two words are frequently swapped for one another.
Faces may be riven, so that each unit shows the natural fracture of the stone, or sawn on some faces and split on others, or worked to a flatter top. Because every unit is small and each one is deep relative to its face, a sett surface is made up of a very large number of individual pieces, and how it looks depends as much on the laying pattern, the joints and the variation between stones as on the stone itself.
This is where setts part company with natural-stone-tile. A stone tile is a thin, calibrated slab bonded with adhesive to a prepared substrate, usually indoors. A sett is a deep masonry unit laid into a bedding layer with jointed gaps between the units, within a ground build-up designed for external use. The two are laid by different trades using entirely different construction, and neither method transfers to the other.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- granite setts
- stone cobbles
- cobblestone paving
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Driveways and entrance courts where a small-unit stone surface is wanted and the ground build-up has been designed for the traffic expected.
- Courtyards, mews surfaces and forecourts, where the scale of the unit suits the scale of the space.
- Bands, borders, fans and edging courses set within larger paving to break up an expanse of slabs.
- Transitions and level changes in landscape work, where small units follow a curve or a fall more easily than large slabs.
- Repair and reinstatement of existing sett surfaces, where reclaimed units are often reused alongside new ones.
- Garden paths and terrace areas where the character of riven stone is the reason for choosing the material.
Consideration
Where it is commonly considered
- Where a small-unit surface is wanted for its character and the ground beneath it is being designed by a qualified professional.
- Where a surface has to follow curves, falls and changes of direction that large slabs would handle awkwardly.
- Where an existing sett area is being extended or reinstated and matching the existing stone and pattern matters.
- Where reclaimed setts are available and their variation in size and face is welcomed rather than resisted.
- Where a band, border or fan of small units is wanted within larger paving to break up an otherwise uniform expanse.
- Where the labour intensity of laying many small units has been understood and allowed for in the programme.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Where the loading on the surface has not been established, since what passes over paving governs the whole build-up and is a matter for a qualified professional.
- Where surface water drainage, falls and outfalls have not been designed, because paving cannot resolve drainage on its own.
- Where accessibility, wheeled use or level thresholds are part of the brief, as those requirements need professional assessment before any unit is chosen.
- Where setts are being considered as a thin overlay on an existing surface, which is a different construction question altogether.
- Where the stone has not been identified, since behaviour varies not only between stone types but between quarries and even between blocks.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Appearance
- Riven, sawn and part-worked setts look quite different from each other, and colour range within a single stone can be wide. Ask to see a laid sample area rather than loose units in a yard.
- Installation dependency
- Setts are laid unit by unit, so the labour content is high and the pattern, alignment and joint discipline depend on the layer. The build-up, bedding and jointing are the designer's decisions.
- Surface wear
- How a stone behaves under traffic depends on the stone, the volume and type of traffic and the way the units were laid. Ask the supplier what is known about the specific stone rather than about stone in general.
- Moisture behaviour
- External paving is wet, drains and dries repeatedly, and what happens to water reaching and passing through the joints is a design question about the whole build-up, not a property of the unit.
- Maintenance
- Joints, staining and localised settlement are the usual subjects of upkeep on sett paving. Ask who would carry out that work and what the supplier says about cleaning this particular stone.
- Substrate dependency
- Everything under the setts - the sub-base, the bedding and the restraint at the edges - is designed rather than assumed, and it determines far more about the outcome than the units do.
- Documentation
- Ask for the stone name, the quarry or source, the supplied dimensions as a description of format rather than a promise, and any test data the supplier holds for that specific stone.
Exposure
Exposure and environmental conditions
- What traffic will this surface actually take, including deliveries and occasional heavy vehicles, and who has been told?
- How is surface water intended to leave this area, and who has designed the falls and the outfalls?
- Is the area shaded, damp or under trees, where organic growth and leaf staining are more likely?
- Could de-icing salts, oil or chemical spillage reach this surface in normal use?
- How do comparable sett surfaces in this area look after several seasons, and can any be visited?
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- The sub-base and bedding beneath setts are designed by a qualified professional for the expected loading and ground conditions.
- Edge restraint is part of the design of any small-unit paving and is decided with the paving rather than added later.
- Falls, drainage runs, gullies and channels are set out with the paving so that the finished levels work as intended.
- Where setts meet other surfaces, buildings, thresholds or manhole covers, those junctions are detailed in advance.
- Buried services under a paved area affect both the build-up and the ease of future access, and should be located first.
- Reclaimed setts vary in depth and face size, and how that variation is accommodated is part of the construction design.
Appearance
Appearance and finish considerations
- Laying pattern - coursed, stretcher, fan or random - changes the reading of a sett area more than the stone choice does.
- Riven faces give an irregular, textured surface, while sawn faces give a flatter and more uniform one, and the two suit different settings.
- Colour variation within a single stone can be considerable, and mixing across the delivery is normally needed to avoid patching.
- Joints are a substantial part of what is seen, so their colour and finish deserve to be viewed in a laid sample.
- New and reclaimed setts rarely match closely, and where they meet the transition is worth thinking about deliberately.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- What stone is this, where does it come from, and what does the supplier hold in the way of test data for it?
- How has this specific stone behaved in comparable external use in this climate, and is there anything to look at?
- What variation between blocks or deliveries should be expected, and how will that be handled?
- What are the most likely causes of settlement or displacement on this particular site?
- How would early movement in the surface be recognised before it spreads?
Upkeep
Maintenance and repair considerations
- How would an individual sett be lifted and reset if it moved, and who would do that?
- What cleaning does the supplier consider appropriate for this stone, and what should be avoided?
- How are the joints expected to be maintained over time, and by whom?
- Are spare setts from the same delivery worth keeping for future repairs?
- How would staining from vehicles, planting or leaf fall be dealt with?
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- Laying many small units is slow work and the programme has to reflect that rather than assume slab-laying rates.
- The build-up, bedding and jointing method all come from the designer, and the layer needs them before work starts.
- Setting out, including the pattern and its alignment to buildings and edges, is agreed before the first unit is laid.
- Access for deliveries and for moving heavy stone around the site affects sequencing and the protection of finished areas.
- A laid sample area agreed on site is the most reliable way to settle pattern, joints and colour mixing.
- Finished paving needs protecting from the rest of the works, since it is usually laid before everything around it is finished.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- The stone name and its source, stated by the supplier rather than inferred from a trade description.
- Any test data the supplier holds for that specific stone, together with what the tests actually covered.
- The supplier's description of the format, face treatment and expected variation across the delivery.
- The designer's build-up drawing and jointing arrangement for the paved area.
- The supplier's cleaning and aftercare guidance for the specific stone supplied.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- What is this surface going to carry, and who has designed the build-up for it?
- Where does the water go, and how has that been set out with the paving?
- Which stone is being supplied, and what is actually known about it?
- How is the edge of this paved area being restrained, and who designed that?
- What laying pattern is proposed, and will a sample area be laid before the main work?
- How will colour variation across the delivery be managed during laying?
- What is the realistic programme for laying this area compared with slab paving?
- Are spare units being retained, and where will they be stored?
- How does this surface meet the building, the thresholds and the adjoining surfaces?
Blind spots
Commonly overlooked points
- Setts are masonry laid into a bedding layer, not tiles bonded to a substrate, and nothing from thin-bed tiling practice carries across to them.
- Almost everything that decides how sett paving performs is beneath it, in a build-up designed by someone other than the stone supplier.
- The unit count is enormous compared with slab paving, which is why labour rather than stone often dominates the work.
- Reclaimed setts vary in size and depth and cannot be assumed to lay like new units of the same nominal format.
- Stone behaviour varies by quarry and by block, so a good experience with one supply says little about the next.
What this page does not do
- This page gives no bedding mix, no joint arrangement, no coursing and no build-up, and none should be inferred; those are design matters for the qualified professional responsible for the paved area.
- Nothing here should be read as an assurance about how any stone behaves under traffic, in frost or over time, since that varies by stone, by quarry and by block and belongs in the supplier's documentation.
- Loading, drainage and accessibility all have to be established by a qualified professional before a paving unit is chosen, not after.
- Where setts are laid over or beside existing construction, the existing build-up should be investigated rather than assumed.
Related entries
Related materials
Materials from the same family, an adjacent role in the assembly, or a shared application.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
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