Driveways, Paths and Patios E-Book

Tony McCormack

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Veröffentlichungsjahr: 2011

Beschreibung

Driveways, paths and patios are an essential part of most properties and this comprehensive book provides a detailed explanation of exactly how they are designed, planned and constructed. Discusses the design of driveways, paths and patios with reference to their planned use, style, size, gradients and special features such as steps, ramps and terraces. Considers the range of materials available including block paving, flags, slabs, setts, cubes, cobbles, loose aggregates, plain & patterned concrete and tarmac. Analyses how to estimate costs and making the choice between the DIY approach and using a professional contractor. Examines the critical issue of drainage. Lays bare the mathematics associated with accurate setting-out and levelling. Describes the range of tools and equipment needed. Details the correct constructions of kerbs and edging and laying methods for flags, block paving and much more.

Leseprobe

DRIVEWAYS, PATHS AND PATIOS

A COMPLETE GUIDE TO DESIGN, MANAGEMENT AND CONSTRUCTION

DRIVEWAYS, PATHS AND PATIOS

A COMPLETE GUIDE TO DESIGN, MANAGEMENT AND CONSTRUCTION

TONY MCCORMACK

THE CROWOOD PRESS

Contents

1 A Brief History of Paving

2 Spoiled for Choice

3 The Design Process

4 DIY? Contractor? Costs?

5 Costings

6 Tools

7 Pavement Layers

8 Setting Out

9 Drainage

10 Laying Block Paving

11 Laying Techniques for Flags

12 Laying Other Materials

13 Steps, Ramps, Stepping Stones and Crazy Paving

14 Completion, Remedial Work and Disputes

Useful Links

Glossary

Resealing products can rejuvenate a tired tarmac driveway and their application is an ideal DIY task. (Gardner-Gibson)

CHAPTER 1

A Brief History of Paving

EARLIEST DAYS

Paving is one of the oldest of all the construction trades and has been used by man since long before we bothered to record history. At some unknown point in time, a human being, no less intelligent than ourselves, but living in very different circumstances, decided to improve the trackway he was using, perhaps throwing some dried rushes and twigs over a swampy stretch to help keep dry his poorly shod feet, and so formed the first ‘improved’ path. And maybe he scattered some sand and gravel, collected from a nearby beach or riverbank, on the area directly outside the family shelter, making it safer for children to play and cleaner for the clan to sit out and eat in the open air, and in the process unwittingly created the world’s first patio. We shall never know, but it is a safe bet that others soon imitated the techniques, and word started going around that the bloke from the tribe over the hill was a bit flighty, and was using poor quality gravel or sub-standard rushes.

Pathways were essential to the development of human societies. They linked families and clans, tribes and kingdoms, providing trade routes and the main means of communication. Gathering areas – what we now often call patios – provided places for meeting and eating, locations where tales could be told, knowledge shared and gossip spread, so that much at least has hardly changed.

The earliest paths were ‘improved trackways’. They had come into being naturally, as humans and other animals followed the easiest line through the landscape, skirting around the wettest patches, avoiding impassable obstacles, looking for the gentle gradients, and gradually developing from a stretch of trampled grasses to strips of bare earth or rock, slowly widened as travellers on two legs and four expanded the edges when their feet, paws and hooves sought drier ground. Dry matter would be added to improve the surface, sand, grit, gravel, rushes, leaves, and then someone would place a flattish stone or two, and we had the first flagger!

In the British Isles, some of the paths and trackways of pre-Roman times are still evident in the landscape. The Ridgeway of southern England along with the Icknield Way are, perhaps, the best known, following the higher, drier ground as they weave across the chalk landscape from Salisbury Plain to the Fenlands of East Anglia. Both are thought to have been used for at least 5,000 years and they probably go back much further than that.

Meanwhile, over in continental Europe the Romans took the principles developed in Mesopotamia, Egypt, Sumeria and Greece, developing and refining road-building technology to a new level. The Via Appia linking Rome with Capua is possibly the most famous of all Roman roads and has been dated to 312BC. The Legions had a well-developed strategy of having their cohorts build the roads as they progressed through a territory, continually expanding the Empire and the Pax Romana. Prisoners, slaves or general labourers followed in their wake, carrying out essential maintenance and repairs.

Modern view of the Ridgeway near Uffington Castle, Oxfordshire.

PAVIMENTUM – THE ROMAN COLONIZATION

The Roman colonization of Britain brought a massive upgrade to some of the traditional trackways, but it was the construction of new routes, with their characteristic ‘straight-line’ alignment, that largely ignored topography, that has come to dominate what we now think of as Roman roads. These represented a quantum leap in pavement technology, comparable to the upgrading of a meandering country lane to a modern motorway. Not only were new construction techniques employed, but also a scientific, logical, methodical approach to paving was introduced. Carefully selected and graded materials, construction in definite layers, provision of drainage, and technically-competent setting-out by skilled workers known as agrimensores, all of which contributed to the basis of the modern civil engineering and surveying professions.

Here, for the first time in these islands, a national standard for construction was imposed, and so well-built were these roadways that several survive to this day, and many more established the route for some of our busiest modern highways. The key to the longevity of these pavements, other than military necessity, was the use of a cambered surface, with distinct layers of different materials forming the structure, and the provision of simple yet effective drainage at the edges. Added to these was the routing, which linked major towns and settlements, and so ensured that the roads were used, valued and therefore worth maintaining.

It is easy to be carried away by the progress such roadways represented and to overlook the fact that some of the techniques used would have been transferred to smaller scale projects. If the Fosse Way and Ermine Street were paved, then feeder or tributary roads would have adopted and adapted some of the principles involved, and access tracks to private dwellings and villas would similarly have borrowed some of the techniques. Indeed, it was in public buildings and the homes of the important citizenry that other forms of paving were used to great effect.

Busy town centres had paved footways and streets, with elementary separation for pedestrians and vehicles. These pavings were mostly of riven flagstones, blocks of dressed or pitched stone laid as setts, or loose gravelled surfacing, although there is a suggestion that timber may have been used in some situations – it’s unlikely to have been stained blue with woad, though!

In the villas, hypocaust flooring used riven flagstone tiles or tegulae to form floors, and in the more important rooms the floors would be covered with mosaics, formed from thousands of tiny tesserae laid on a basic concrete known as opus signinum. Many of these mosaics were manufactured off-site, usually in southern Europe, prefabricated by highly skilled master mosaicists and selected from a catalogue by the client. They would be brought in to building projects when required and be laid by local tradesmen, much in the way that we do now with a feature patio.

Out of doors, function was far more important than form, and so courtyards were paved by using flagstone, setts and cobbles, with local materials dictating which style of paving was the most suitable. Where the local geology provided only poor or soft stone, beach or river cobbles, washed down from harder rock-beds miles upstream, could be used to provide a simple, hard-paved surface.

1,200 YEARS OF POTHOLES

The Roman control of Britain ended in the fifth century and with the loss of that control the last planned and methodical maintenance of the road network, so essential to ensuring military supremacy and the rule of law, also ended. The skills must have survived, but the political will was gone, and it would be a thousand years before any real political effort to maintain a serviceable road network would return.

The Dark Ages came and went, the Angles, Saxons, Jutes and others pushed their way in and paid scant attention to the finery and feats of their predecessors. They would use local materials to provide hard-standing for essential areas and fill in the odd pothole or two when it threatened to dislodge a wheel from their favourite cart, but paving, as a skilled trade, was relegated as the provision of food and shelter took precedence and the road network fell into decline.

Although they seem coarse and uncomfortable to modern taste, pitched stone roads were the best option for hundreds of years.

The Vikings also came and continued in much the same manner. Their towns would use stone paving in the busiest sections, but it was the responsibility of individual landowners to provide any hard surfacing that was required. Merchants and craftsmen might put down a few setts, cobbles or flagstones outside their place of business, perhaps to minimize the amount of mud and worse carried into their premises on the shoes and boots of customers, and there would be flagstones on the floors of the more upmarket properties, but most homes would rely on hard-packed, earthen floors with straw changed at irregular intervals.

Actual construction methods varied throughout the Roman Empire to make best use of local materials. This cross-section illustrates a typical construction for a British road which would be surfaced with gravels, rather than paved with flagstones or setts.

The Normans brought back the traditional skills of masonry, driven by their intensive programme of castle building, and the craft of the stone workers was employed for both vertical structures and for floors and courtyards. The basic tools used by Norman masons and paviors remain with us still. Hammers and wedges to split the stone, chisels and punches to dress it, and mallets to settle the stones into the bedding.

And so it went on. It was during the Tudor period, in 1555, that an Act of Parliament created the position of Surveyor of Highways, which was unpaid, unpopular and ineffective. Parishes were required to maintain their area’s roads and a bursary was issued to the local population who were required to ‘mend their ways’.

TURNPIKES, TAR AND TECHNICAL IMPROVEMENTS

It took until the late seventeenth century before properly maintained turnpike roads were established. The tolls imposed were used for their upkeep and extension, and the first successful road of this type was the Great North Road, now more commonly known as the A1. Other turnpike roads were developed throughout the later seventeenth century and their financial success led to their being expanded significantly throughout the following century, a period that saw ever improved designs and construction methods. However, as the road network expanded, so did the traffic, and contemporary construction methods struggled to cope. Surfaces became rutted and potholed; some of the turnpike trusts were less than honest when apportioning funds, and for the first time in centuries the quality of roads deteriorated.

Luckily, a number of men applied their thoughts to these matters and gradually, thanks to their efforts, significant improvements were made, improvements that formed the basis of modern road and pavement construction technology.

Despite his inability to see what he was doing, Blind Jack of Knaresborough, more properly known as John Metcalfe, created 250km (160 miles) of turnpike road in Yorkshire that relied on a cambered surface and drainage ditches at the edges. Sound familiar? The master civil engineer Thomas Telford understood the critical need to drain pavements properly, and so developed a system using pitched stones overlain by layers of progressively smaller sized crushed stone and gravels, with camber or crossfall to drain surface water to roadside ditches.

John MacAdam developed his now legendary ‘macadamized’ system while employed as surveyor to the Bristol Turnpike Trust in 1816. This relied on using a fine crushed stone to bind together granite chippings and/or gravels laid over larger crushed stone, with a pronounced camber to the structure that would ensure water was shed to either side of the pavement, where it could not compromise the foundations. His fame spread: he was appointed Surveyor-General for Metropolitan roads and, before long, his methods were adopted throughout the western world.

By the time Victoria came to the throne, there was an extensive network of good quality roads, and it was the vehicles in use that limited speed and journey times rather than the surfacing. With a lightweight carriage and a good team of horses, speeds of 12mph were typical, and over a period of about fifty years, the journey from ‘Cottonopolis’ (Manchester) to London was cut from four days to a little over 36hr.

By this time, towns and cities had well-developed paving and surfacing for both carriageways and footways. Flagstones were hauled from the Pennine quarries all the way to London. Granite from Cornwall, Aberdeen and Wicklow was popular throughout the islands, and those clever Victorians were experimenting with new materials. Complaints regarding the noise from horses’ hooves and iron-rimmed wheels as they traversed the granite setts of the streets of Westminster and London led to experiments with rectangular and hexagonal wooden ‘setts’, and then with the new wonder material of the age, rubber. Timber had a relatively short lifespan, three to four years was typical, but it was popular because traffic noise was significantly reduced, so much so that properties on wooden-paved streets attracted premium rents and lodging rates.

Telford’s construction, on the left, was refined and enhanced by MacAdam; their work remains at the heart of modern pavement construction technology.

NEW MATERIALS

Tar macadam has several alleged ‘inventors’. Its immediate predecessor, asphalt, is documented as being used in Paris in the 1850s and seems to have appeared in London and Dublin within a decade. Tarmac, as we think of it today, was first patented in 1902 by Edgar Purnell Hooley, a surveyor from Nottingham. The tale is that he had noticed a wonderfully smooth section of roadway near Denby in Derbyshire, and found that, where a barrel of tar had been accidentally spilled, it had been covered with furnace slag. His patent, which became the foundation of the modern company Tarmac plc, covered the heating of the tar and the subsequent addition of ground slag, macadam and small stones.

The other great nineteenth century advance in paving materials came with the development of Portland cement. In 1824, Joseph Aspdin, a Yorkshire stonemason and bricklayer, was granted a patent for the cement he had developed from a mixture of crushed limestone and clays that was heated in a kiln and then ground to a powder. The product hardened when water was added, and he at first thought it resembled the popular building material Portland stone, hence the name.

Lime and gypsum mortars had been known since the time of the pharaohs, and the Romans had developed pozzolanic concrete by using the volcanic ash found near Pozzuoli in Italy. In 1756, John Smeaton had developed what is considered to be the first modern concrete by mixing pebbles with powdered brick dust. Portland cement took this to new levels of possibility, as its tremendous compressive strength and versatility redefined construction technology.

Portland cement concrete became a bedding material for many other pavings and surfacings, and experiments with casting led to the development of regular, uniform concrete flags as replacements for the somewhat haphazard stone flags that often had to be hauled hundreds of miles to where they were needed. The first ‘standard’ for concrete flags was published in 1929, and from thereon, there was a steady decline in the use of stone flags.

The advent of the railways had greatly improved logistics, and standardized building materials were becoming more widely available. Good quality clay bricks for masonry and paving – which had previously been restricted to their own local area – could now be delivered anywhere on the rail network; their use spread, along with that of the decorative clay edging tiles and diamond-pattern pavers that are now highly prized in reclamation yards.

Concrete block paving came to us from Europe. Devastated by two World Wars, the need to rebuild towns and cities quickly and cheaply led to the development of paving blocks that could be manufactured by pressing concrete instead of kiln-firing clay, and could be laid faster and more easily than concrete flagstones. Block paving first appeared in Britain during the 1970s but really took off in the 1980s, when local authorities looked to pedestrianization as a way of rejuvenating tired but busy towns and cities. At that time, tarmac was popular but was seen as soulless, while concrete flags had become the norm, used anywhere and everywhere for public footpaths, driveways, town centres, civic squares and shopping centres. Block paving offered flexibility, modern styling and, most of all, colour. Town after town, city after city ripped up the old paving and installed block paving in the rush to revitalize their municipalities and attract shoppers and commerce.

Concrete reproductions of items such as reclaimed railways sleepers have become popular as casting technology has improved. (Longborough Concrete)

What householders saw in the towns, they liked, and wanted it on their driveways. The 1990s saw concrete block paving become the most popular form of paving for new and reconstructed driveways. As personal wealth and leisure time increased, those same householders began to look at ways of improving their gardens as well as their driveways, and the great patio culture began, driven by aspirational television makeover and lifestyle programmes. The range of wet-cast products grew each year to meet a seemingly insatiable demand for new products, which were increasingly new versions of old products: wet-cast concrete copies of old stone flags.

As the millennium ended and a new century began, the breadth of paving materials available had never been wider, but still the driveway- and patio-buying public looked for more. Stone flags from India, granite setts from China, new textures and formats for block paving, concrete castings of old timber sleepers, patterned and stencilled concrete … it is an exciting time for paving.

Driveways are an essential part of a home and have become significantly larger over time. (Blockleys)

MODERN TASTES

The use of residential paving has changed over recent years. Originally it kept our feet clean between the public footpath and the house. A simple path of tiles or flagstones was sufficient. The growth in car ownership over the last fifty years has meant that a driveway has become an essential component of a home, and now a single driveway is not enough: we need double or triple driveways since many homes have more than one car. At the back of the house, the garden is now a lifestyle statement and an essential part of that styling is a patio. Socializing in the garden is now an accepted part of our lives and we spend more and more of our income on ‘leisure’ with each passing year.

The presence of an acceptable driveway and a reasonable patio are key selling points when a property is put on to the market. A driveway has to have ‘kerbside appeal’. The ability to park a car next to the house is not enough; it has to portray a lifestyle, it has to make us want it, to envy the generous width, to desire the security it offers, to long for the way it leads the eye to the well-appointed and impressive main entrance. Two strips of concrete flags with gravel chippings between them is no longer adequate. A driveway tells the world about the status of its owners, their hopes, their expectations, their standards and their way of life. An attractive and functional driveway can make the difference between a house selling in days and its languishing on the market for weeks. A shabby, weed-infested, miniature rectangle of dirty tarmac, crumbling concrete or broken flags hints at what lies behind the front door, at what sort of people live there. The driveway is the entrée, the starter course, and as such it whets the appetite and sets the tone for the remainder of the meal that is a home.

Terracotta pavings bring a touch of the Mediterranean to our gardens. (Marshalls)

The patio is a more private area and, unlike the driveway, is normally seen only by invitation. To be invited on to the patio is to be admitted into the inner sanctum – you are an honoured guest of the family, a friend, a confidante, you are accepted. The milk and the bins, the post and the papers, all come to the house via the driveway, but only the favoured few make it on to the patio, it has become that most awful of television makeover clichés: a room outdoors.

A patio has to perform many functions. (Bradstone)

But it is not a room, it is a space, and a transitional area between house and garden; it performs some of the socializing functions of the house, but it has to blend with the garden. It needs to suit the architectural styling of the house, yet continue the themes of the internal décor. It is the crossroads between indoor and outdoor, between form and function, between duty and leisure. It needs to provide a viewpoint for the garden, a taster of what to expect, a summary of its style or theme, but it also needs to be easily maintained and to make the best use of the space available.

Fashion has come to the patio. The types of material used will help to define it as classic, retro, modern or avant-garde, and dictate what type of planting, what type of furniture, what type of lighting should be associated with it. As will be seen later, choosing materials and designing a patio require an acknowledgement of the existing, an understanding of the possible, and an aspiration for something that defines the home and the family. A classic styling will probably never be out of fashion, but may be seen as too safe or too conservative. Retro places the patio in a specific period and imposes a limitation on what can be used and what can be planted, but evokes a particular sense of period. Modern styling is clean, simple and uncluttered, but for how long will it be modern? ‘Decking’ was modern for a few months in 1999 and is now well past it, according to some. Avant-garde forces people to think, to ponder, to provoke a reaction, to commit them to liking or disliking – there is no middle ground; it is love or hate, and is so highly individualistic that it is possibly not the best look for a house that is being put on the market.

What is your style? Do you know? Does it matter?

FUTURE TRENDS

Fashion is fickle, it seems to emerge fully formed from the ether. Is it pushed forward by the manufacturers or are they dragged along in its wake? Do the media pundits and makeover programmes show us what we want, or what they want us to want? Predicting what will be fashionable next season is a gamble, even for those of us immersed in the paving trade, but there are some general trends that it may be assumed will be with us for the next decade or so.

Natural materials are in: flags of sandstone, quartzite, porphyry and limestone, setts of granite, whin and diorite, terracotta and travertine tiles, tumbled clay pavers, self-binding gravels. New materials are favoured, but there is a steady level of demand for the reclaimed and a growing demand for the recycled. The styling is modern, with touches of tradition, but individualistic and quirky. Good looks, plenty of space, high quality workmanship and ease of maintenance are not enough, a modern patio has to be a conversation piece.

Concrete products are fighting a rearguard action and are being driven in one of three directions: to extremely high quality and faithful reproduction of natural materials; ultra-modern chic, clean lines and minimalist styling; or dirt-cheap, budget bargains. There is a need for all three and none will ever dominate. There needs to be such offerings to provide the range of choice we now demand, even if it is only to compare and contrast.

Tarmac will still have its adherents because it is simple and functional; but new, updated looks will be sought – coloured macadams or resin-bound surfaces to inject a more playful or idiosyncratic styling. Decorative concrete will similarly remain moderately popular, but the standard of workmanship is the biggest problem facing that sector of the industry, and, unless it improves its image and stops shooting itself in the foot because of the antics of a few installers, it will never be more than a minority taste.

Clean lines and classic colours create a contemporary look for this patio. (Stonemarket)

Overall, the public are looking for quality rather than a bargain. There will always be a cost-obsessed core looking for ‘cheap’, but, increasingly, the public cares more about a high standard of workmanship than a rock-bottom price. The past fifteen to twenty years have taught them to be wary and sceptical of contractors, and the trade has only itself to blame. We have abandoned traditional apprenticeships and forgotten how to train the flaggers, kerbers and block layers of tomorrow. We in the trade allow anyone to set themselves up as a paving contractor and then complain about the number of cowboys in the trade. We believe that we work to high standards and act with integrity, but we cannot organize an effective trade body to ensure that we actually meet and maintain those laudable ideals.

The rest of this book looks at how things should be done, whether by contractor or the DIY-er. It aims to promote best practice and to provoke discussion on design and materials and methodologies. It can never be fully comprehensive, but I hope that it inspires, encourages and helps in some small way to ensure that the reader gets the patio, path or driveway that he or she desires and deserves.

CHAPTER 2

Spoiled for Choice

INTRODUCTION

Almost fifty years ago, when my father started his paving company, there were flags, there was concrete and there was tarmac. Choice was limited, but simple, straightforward and uncomplicated. Now, in the early part of a new century, we have dozens of manufacturers, each producing glossy, full-colour brochures with page after page of choices, options, variations, colourways, sizes, stylings and possibilities. We have never had it so good, as someone once said, but so much choice brings problems in itself. Just which do you choose, what is best for you and your project, and who are the better manufacturers? This section aims to explore the more popular products, show what is available, give tips and hints on how to select the most appropriate, and give a general push in the right direction.

BLOCK PAVING

Concrete block paving of one form or another is the most popular choice for residential paving and has been so since the early 1990s, when economies of scale resulting from the considerable investment in new production plants by a handful of major manufacturers brought the price per square metre down to a more realistic level. Demand grew and so did the number of ‘block paving specialists’ that suddenly appeared on the scene.

At the time of writing (early 2005), block paving sales for the United Kingdom are expected to total around 28 million square metres (m2), and it is domestic driveways, paths and patios that comprise the bulk of this figure, approximately 17 to 18 million m2 per year.

From the basic, original, rectangular ‘brick’ format, the range of options has expanded and the property owner is now faced with a sometimes bewildering array of choices – of colours, of sizes, of shapes, of textures, of thicknesses, of styles … so much so that some manufacturers are now limiting their production to just the most popular pavers in an attempt to reduce confusion. However, not a year goes past without some new paver entering the market, and what follows is a brief examination of the main types.

Concrete and Clay

The biggest distinction between the types of block and brick pavers is between those manufactured by pressing concrete into a mould, what we call concrete block pavers or CBPs, and those pavers created by firing clay bricks in a kiln. They are compared in the table overleaf.

Concrete Pavers

Methods of manufacture Britain differs from most other countries in that the majority of the pavers turned out by manufacturers are a ‘through colour block’: they are made from one mass of concrete with colouring right through the block. Pavers from Ireland, continental Europe and elsewhere are usually ‘face mix blocks’; these use a high quality concrete with all the necessary colouring dyes in a separate 8–12mm layer on the top surface of the blocks, with an economy ‘backing’ used for the lower layer that will never be seen once the paving is complete.

A small selection of the many types of block paver now available. (Tobermore)

There is no compromise of quality with Face Mix blocks. They are not prone to frost damage nor delamination. They have been used without problems in Europe for forty years or more, and our continental neighbours endure far harder frosts than we ever get in our mild, maritime climate. The face mix is pressed on to the backing mix within seconds: there is no ‘joint’ between the two, no plane of weakness. Both Face Mix and Through Colour blocks have to meet the same standards of strength and durability. In fact, there is a good argument to be made that Face Mix blocks are a superior product: the expensive dyes can be concentrated in the upper layer, where they are needed, and not dispersed through the whole block. Similarly, the face mix can be manufactured from the highest quality aggregates, while the backing mix can include reclaimed or recycled aggregates. As long as the strength requirements are met, there is no structural problem in using a lower quality concrete for the backing mix. One British manufacturer estimates that face mix products offer a cost saving of around 70p per m2, compared with through colour blocks using high-quality aggregates and dyes throughout.

Face mix has all the colour concentrated in one layer on the top ‘face’ while through colour blocks have the colour dispersed right through.

Comparison of Concrete and Clay Pavers

Concrete block paversClay paversCostLow, from £7/m2Normally more expensive, £12/m2 and upwardsProsLarge choice of shapes, colours, textures and styles. Dimensionally accurate units for accurate laying. Range of block depths to suit all applications.Exceptionally hardwearing. Natural non-fade colours. Some patterned formats available.ConsColours prone to fading. Aggregate can become exposed with wear and weathering.Sizes variable due to firing process. Prone to colonization by mosses. Mostly square or rectangular. Relatively hard to cut. Limited choice of block thickness.LifespanAt least 20 yearsClay pavers from the sixteenth century are still in use.

The red-multi ‘brindle’ colour is the favourite choice for most residential driveways; it is usually edged with blocks of charcoal, buff or both. (Formpave)

Standard pavers The most popular format for the concrete paver in Britain and Ireland is a 200 × 100mm rectangular block, having a depth of 40–80mm, with 50mm being the most popular for residential driveways. The blocks are available at a relatively low cost (£7–10 per m2) in a range of single colours and multi-colours. The most popular multicolour is a red-grey mix commonly named ‘brindle’ and this is often combined with edge courses of a single colour, such as charcoal or buff, to create an attractive contrast.

For the main paved area of a driveway, termed the ‘body’ or ‘field’ of a pavement, a multi-colour block is a good choice. The mottled colouring is better able to disguise minor stains and markings, whereas single colours often emphasize any spot or mark that differs in any way from the rest of the paving. However, the manufacturers supplying the British market have two different ways of creating the mottled, multi-colour effect. Most incorporate two or more coloured concretes within each block, and so no two blocks are the same; each contains a variable proportion of the coloured concretes in an infinite variation of pattern within each block. A minority of manufacturers achieve their so-called multi-coloured effect by mixing blocks of slightly different tones. So, for a brindle multi-colour, the manufacture may provide five or six different shades of red and grey blocks that need to be randomized before being laid to avoid a patchy appearance within the finished pavement.

Standard blocks are most commonly laid in one of three patterns: herringbone, stretcher (running) bond, or basketweave. Of these, herringbone offers the highest degree of interlock and is therefore the ‘strongest’ pattern and the one most commonly recommended for driveway use; stretcher bond offers less interlock, as there is potential for movement between the courses; and basketweave is the weakest of the three, as there is potential for pattern creep in both the transverse (side-to-side) and the longitudinal (top-to-bottom) direction. Other patterns are possible, but they are more complex to lay and often weaker than the basic herringbone pattern.

Standard blocks offer a 2:1 format – each block is twice as long as it is wide. There are variations based on 3:1 and even 4:1 formats, and, while these are fine for driveway and patio use, they may not meet the requirements of the relevant British Standard which requires a length-to-width ratio of not more than 2:1. However, some people feel that these alternative formats offer enhanced aesthetic appeal.

Tumbled pavers Some years ago, in a faraway land, a man sat on a beach and watched the waves tumbling a brick back and forward, rounding off the corners, distressing the edges, imparting an aged, timeworn character to even the newest of bricks. In a flash of inspiration he realized that the tumbling action created by the waves could be replicated by machinery and used to age and distress concrete blocks, particularly paving blocks; and so the tumbled block came into being. The most famous of these products traces its roots back to the original inventor and is licensed to manufacturers all over the world, who manufacture the blocks in sizes and colours to suit their local market and then sell them under the registered trade name Tegula, from the Latin for a tile.

A selection of popular laying patterns for 2:1 ratio rectangular blocks.

Tumbled blocks laid to a sweeping arc. (Tobermore)

Tumbled blocks are often used to create circles, either as features ‘inserted’ into an area of coursework or, as in this image, as the central feature of a paved area. (Brett)

The popularity of the Tegula block inspired many imitators, that are sometimes referred to as ‘rumbled’, but the basic premise remains that a block is rolled over and over in a rotating, cylindrical drum, bashing against the drum and against the other blocks, until it emerges some minutes later in a thoroughly bedraggled, but value-added condition. Since the original development of the Tegula system, alternative methods of distressing blocks have been developed, and some have made their originators quite wealthy, but the end result is generally the same – a bashed and battered concrete block with its corners and arrises (edges) missing.

There are some exorbitant claims made for these tumbled pavers. Manufacturers grandly claim that they ‘replicate time-worn stone pavings from yesteryear’, which is somewhat fanciful, but there is no denying that the finished product certainly does have its charms and is much more sympathetic to older properties, or ‘homes of character’, than the modern, geometric styling of standard blocks. It also avoids the often pathetic attempts to replicate traditional setts. The big selling point for these tumbled pavers is that they offer all the advantages of modern block paving, such as cost savings and ease of laying, but may be used with some success on properties where stone setts or flagstones would previously have been the only choice.

Some blocks mimic the slightly domed surface often found with gritstone setts. (Stoneflair)

Decorative pavers This category is where we lump all the blocks that do not fall into one or other of the previous groupings. It includes those that are ‘different’ in some way, which generally means in texture, shape and size, or a combination of these. Non-rectangular shapes are generally manufactured in moulds, just as are the standard and the tumbled pavers, and there is usually an underlying mathematical principle that allows them to be mixed and matched with blocks from the same range into suitable patterns, or with blocks from complementary ranges to create distinctive layouts.

Special textures are most commonly formed by ‘secondary processing’, which involves subjecting the block to additional treatment following its initial manufacture. It may be washed or polished to expose a decorative aggregate, or shot-blasted or bush-hammered to create a more stone-like surface. Secondary processing, which includes the tumbling process mentioned above, always involves extra manufacturing costs, and these are reflected in the retail price of the pavers.

Clay Pavers

Methods of manufacture Clay bricks have been used as paving materials for hundreds of years. Bricks from the fifteenth century can be seen at Hampton Court to this day, which bears testament to just how hard-wearing fired clay can be when used as a paver. Note how the trade often refers to clay ‘bricks’ rather than ‘blocks’, although they are also known as pavers, paviors, pavoirs, pamments, or simply as ‘clays’.

A 4:1 ratio, textured block paver laid in stretcher bond. (Tobermore)

Clay pavers come in a wide selection of colours. (Baggeridge)

Originally, clay pavers were made in the same way as other bricks, what we now call facing or common bricks. Experience led to certain types of clay and methods of firing being identified as resulting in a type of brick that was durable when used ‘on the flat’ and in permanent contact with the ground. It is worth noting that not all clay bricks are suitable for use as pavers. Many new and reclaimed facing (house) or common bricks do not have an adequate level of frost resistance to cope with their being used in damp conditions, which often results in the ‘spalling’ of the surface. The worst of them degrade to a mush after a few years, which is why the use of facings or ‘house’ bricks is rarely recommended for use in paving projects. Further, many facing or house bricks do not have a true 2:1 ratio that enables them to be laid in accurate interlocking patterns.

Most modern clay pavers are manufactured in production plants dedicated to manufacturing ‘facings’. The methods and materials used are similar, and so their manufacture complements the production of ‘house’ bricks and can be a profitable line for factories with access to suitable clays. There are only a handful of British factories producing clay pavers, and only one or two have facilities exclusively dedicated to the production of pavers.

The level of demand is barely a tenth of that for their concrete cousins, and this is largely due to the historical price difference. However, as CBP manufacturers have brought out high-value products (such as the tumbled and decorative blocks mentioned earlier) clays now find themselves as a mid-price product and this has helped to stimulate demand.

Different colours of clay pavers are manufactured by blending different clays before firing. The most common method of manufacture involves the prepared clay being extruded and then sliced into brick-sized pieces. This slicing of the extruded clay is responsible for the classic ‘dragwire’ texture observed with many modern pavers. A small proportion of pavers, known as ‘stock pavers’, are moulded – the clay is literally thrown into a mould of the required size and shape to create a highly distinctive look and texture.

The raw bricks are arranged into stacks and allowed to dry out before being transferred on a ‘kiln car’ to a gas-fired tunnel kiln where they are fired at high temperatures (1150°C) for an extended period. The position of an individual brick within a stack, and the position of that stack on the kiln car, the firing conditions of the kiln (known as oxidation or reduction firing), and the ‘top firing’ temperature, all have a direct affect on the finished appearance and colouring of the brick.

Once fired, the bricks are allowed to cool in a controlled manner while still inside the kiln. Once cooled, however, they can be packaged, shipped and used immediately. All this care and time, not to mention the fuel to fire the kiln, make clay pavers more expensive than concrete blocks, but the cost is often of secondary importance on projects where clays are used. It is their durability and colour-fastness that makes them attractive to designers and specifiers. After the hit-and-miss success with concrete pavers on the pedestrianization schemes of the 1980s, clay pavers offer a surface that will be the same colour twenty years on as it is today, and will not be worn away by stiletto heels and delivery vehicles to reveal a less-attractive and differently-coloured aggregate.

With a smaller market share, there is less demand for variety from clays than is the case with concrete blocks, but, again, the pavers may be arbitrarily divided into the three groups discussed above: standard, tumbled, and decorative.

In terms of colour, there are four main groupings, but an almost continuous spectrum of colour from buffs to brown, through red and beyond to the deepest indigo blues is available. As the clay used in their manufacture is a natural material, it is almost infinitely variable, which is part of its charm, and this variability enables local or regional colouring to be used as part of a larger hardscape.

Reds are probably the most popular colours, containing true ‘brick’ reds and a huge range of blends that incorporates russets and browns, tans, oranges, beiges and even blacks. The buffs and browns offer softer, muted, more organic and less strident tones and hues. Buffs bring lightness to darker or shady areas, while browns are earthy and sympathetic yet offer an ability to disguise minor staining. The blues typically hail from Staffordshire, where the local marl clay produces an incredibly strong and heavy brick. Many of the nation’s railway bridges and tunnels were constructed from bricks manufactured from the Staffordshire blue. From a designer’s viewpoint, the blues are usually considered too dark to be used in creating large areas of colour, and so their most common use is as a contrast to other colours, as band or edge courses.

Standard clays These are the basic, rectangular ‘bricks’. They may be chamfered or chamferless; they may have spacer nibs or be nibless; their dimensions may be in the ratios 2:1, 3:1, 3:2 or some other value, but they are typically bricklike.

Tumbled clays Tumbling or distressing is a relatively modern development, taken in response to the overwhelming success of tumbled concrete pavers. The tumbling of clay pavers imparts a genuine aged appearance. When concrete blocks are distressed, the process exposes the internal concrete structure, which is not always as attractive as the untrammelled surface. However, with clays, all that is revealed is more fired clay, exactly the same as that on the surface, on the sides and on the base.

Tumbled clays have an uncanny ability to look reclaimed from the moment they leave the factory. They do not suit every job, but for projects in gardens or where they are part of a larger softscape, tumbled pavers bring a natural and gentle feel to what could otherwise be a hard and austere surface.

Tumbled clays bring an added texture to a pavement. (Marshalls)

Decorative clays There have been decorative clays for decades, longer than we have been using concrete pavers of even the most basic form. One of the most popular forms has been the ‘diamond’ paver, a thinner paver that is right on the border between tiles and bricks (which we in the trade arbitrarily set at 30mm). There are also the ‘stable’ pavers, sometimes known as ‘chocolate block’ pavers because of their distinctive form. Their natural durability and resistance to wear made them an ideal choice for stable yards that experience severe abrasion from hooves. Previously, such yards had been cobbled with hard river or beach stones, or paved with hardstone setts, both of which are labour-intensive and difficult to lay (explained below). Mass production and improved logistics thanks to the canals and railways made these tiles widely available and much easier to install.

The idea of using a pattern or moulded texture never went away, but over recent years new designs have been produced, some more successful than others, but the old favourites persist .

Diamond-pattern clay pavers have been a favourite for over a hundred years. (Baggeridge)

FLAGS AND SLABS

They are called flags in northern Britain, shortened from the older term ‘flagstones’ which is used to describe the large, flattish sections of rock that have been used for centuries to provide a serviceable surface for man and beast. In the south of England, and a few other parts of these islands, they are referred to as ‘slabs’, derived from the term used to describe large bays of concrete. Whatever they are called, they have an important role in paving of all scales, from garden paths and patios to the largest urban hardscape scheme. There are two classes of flag: natural stone and concrete. The types of stone or concrete may be used to further categorize the flags, but for now, classifying them as stone or concrete will suffice.

Stone Flags

Stone flags vary according to the local geology, and some types of rock are so suitable for use as flagstones that they have been exported beyond their regional boundaries to all corners of the country, and, indeed, to all parts of the world. Yorkstone from the Pennines of northern England can be found on projects in Gibraltar, Singapore, Australia and North America. We now see sandstones and limestones from India being imported to Europe, but this is less to do with the quality of the stone and more to do with the cost of labour in developing nations.

Stone flags do not come out of a quarry as perfect rectangles of regular thickness. They have to be worked, either by means of tough machinery or time-consuming, manual labour. Once, most flags were handworked, what is known as ‘quarry fettled’, but modern technology crept in and the vast majority of British and Irish flagstones are now cut and finished by machine. In contrast, much of the flagstone from Asia and Africa is still quarry fettled and the natural look has helped to establish it in the modern marketplace for garden and patio paving.

A selection of colours and textures readily available from local stockists. (Stonemarket)

Concrete Flags

It was the difficulty in working stone, both in terms of machinery and manpower, combined with its inherent variation in character and the logistics of moving it from where it was quarried to where it was needed, that originally drove the market for a more amenable alternative. With the production of reliable cements from the 1900s onward and consequential developments in concrete technology, it was not long before someone started knocking out a concrete version of a basic flagstone to meet demand. Suddenly, there were strong and durable flags that were of regular size and regular thickness, of a consistent quality, and manufactured locally at a fraction of the cost involved in quarrying and hauling stone across the country.

Patio area paved with a grey-toned imported sandstone.