A Guide to Paving,

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	Drainage & Hard-Landscaping in Britain & Ireland	Keep up-to-date: Sign-up for the Mailout more info Buy the Book On This Page... Introduction   Terminology   Component Layers   Paving Materials   Associated Topics   Education Links   Awards, etc
	Introduction All paving, from the simplest garden path to a 14 lane superhighway consists of a number of different layers. It is the materials used for each layer, and the way each layer is prepared and constructed that gives strength and stability to the many types of paving. Typically, there are four main layers to a pavement and these are introduced below, however, some paving types, such as shredded bark or gravel will have fewer layers, whilst heavy duty applications may contain 5 or 6 identifiable layers.   There is a brief description of various types of paving given below, and these are detailed in more detail on separate, linked pages within this site. We have arbitrarily divided the many forms of paving into Natural Materials, that is those materials that are not overly processed, and Manufactured Materials which should need no explanation. Further pages within this site discuss various other topics and aspects of the hard landscaping industry, including Trade Tips, Maintenance, simple drainage and an introduction to the services we offer to the trade and the general public.   Pavingexpert.com is grateful for the continued support of SureSet.       Terms, Units and Definitions: We have tried to avoid jargon or overly-technical language throughout this site, but there may be one or two terms that you don't understand. Some of the technical terms are emphasised like this....putting your mouse over these terms will cause a definition to 'pop-up' in modern browsers. This site uses metric units of measurement because that is what is used in the British and Irish paving and civil engineering trades. However, it's appreciated that some people prefer to live in the past and continue to use an outdated, overly-complicated base-12 system. To aid the understanding of these Luddites, there is a "Pop-up-and-stay-up" rough guide to the most commonly used metric dimensions. Click here to open the Units pop-up. There is a lot of regional variation in paving terminology - for example the paving units known as "slabs" in Southern England are referred to as "flags" in North-West England. We are sure you will get the hang of it. Email us if you're really stuck, or if you find a glaring mistake!

The component layers of a typical pavement

A pavement is any surfaced construction used to carry foot or vehicular traffic. It includes footpaths, patios, hardstandings, roads, driveways, motorways, and even airport runways. There are rigid pavements constructed from large bays of reinforced concrete and flexible pavements constructed from many other materials, including tarmacadam, and blocks of concrete or stone (block pavers, flags, setts, etc.). Monolithic pavements are constructed from materials that bind together to form a single mass, such as tarmacadam or concrete, whereas elemental pavements are constructed from individual components, such as flags, setts, block pavers.
The most commonly encountered layers are detailed below....
Sub-grade	The sub-grade layer is essentially the existing ground, cleared of any organic material. This may or may not require preparatory work, depending on chosen paving type and existing ground conditions. Sub-grade layer
Capping Layer	An 'improvement' layer, usually laid over the sub-grade to strengthen or re-grade the existing ground. Only used on heavy applications and usually composed of crushed rock, hardcore or a cement-bound material up to 600mm thick.
Sub-bases	This is the load-bearing layer of the pavement. Typically constructed from crushed and graded stone. Essential beneath pavements subject to vehicular traffic, it may be omitted in certain other applications. Sub-bases
Base Courses (Binder Course)	Most commonly, this is a layer of bound material, (cement-bound or bitumen-bound) at the bottom of the surfacing layer. Normally only used in heavy applications, notably public carriageways, it is sometimes referred to as the Road Base when used beneath a tarmacadam, asphalt or block paved surface. The term is also used to define a compacted soil layer tested as part of the California Bearing Ratio (CBR) process to determine ground 'strength'. Base Layers
Wearing Course (Surface Course)	In a tarmacadam or asphalt pavement, the visible upper surface layer that carries the traffic. Also known as the surfacing or a 'carpet'. Surface Course Layers
Laying Course	Also known as the "Bedding Layer". In an elemental pavement such as block paving or flags, this is the layer that carries the final surface layer. For segmental paving, this is usually a coarse grit sand, with a low clay content and with good drainage properties. Laying Course
Paving layer	The final hard surface of an elemental or segmental pavement. This may be concrete or clay blocks, pre-cast concrete flags, natural stone or any other form of paving. Paving layer
Other considerations
Jointing	This is determined by the type of paving. Flags may be pointed with a mortar, whilst most popular brick/block pavers are jointed with a clean, fine sand. Cobbles and setts can be jointed with pitch or with a cement or resin mortar. Mortars
Drainage	All paving should be designed to drain freely to gullies or other disposal points. Recommended fall is usually quoted as 1 in 40; In practice, 1 in 80 is adequate for smaller, domestic areas. Drainage

Paving Materials
A brief description of the major paving types commonly used in the UK. Click on links or icons to view pages dealing with each type in much more detail. Natural Materials
Paving Type	Description	Comments
Bark	Shredded Tree Bark	Very cheap and easy to install. May need regular 'topping-up'. Only really useful in garden/landscape settings, ideal for kids play areas. Organic. Readily available via Garden Centres. Medium maintenance requirement.
Gravel	Small pebbles	Rounded or angular pebbles, usually in the 3mm to 18mm range. Vast range of colours and sizes. Cheap. Good for paths, drives and in the garden. Low maintenance.
Setts/Cubes	Natural stone blocks	Beautiful when they're laid properly; bloody awful when they're not. Typically in the range 50x50x50mm to 350x200x250mm, and every possible size in between! Variety of rock types and colours. Can be quite expensive. Reclaimed setts are readily available. Low maintenance. Will outlast most of us!
York, Slate, Natural Stone	Flat slabs of natural stone	A paving of real character, often with an unmistakable riven appearance. The legendary 'York Stone' flags hail from the pennine grits of Northern England, although many other types of local and imported stone are also used for paving. Some of the most visually attractive work is done in natural stone and slate. New and reclaimed flagstones are available. Quite expensive. Reclaimed flags can sell for £40-60 per square metre and it has become a popular item for the Drive Bandits to remove entire drives overnight. Low maintenance.
Cobblestones Duckstones	Large Rounded Pebbles	Name varies depending on locality, but usually rounded and from a beach or fluvial source. Huge variety of size, shape and colour. Reasonable price. Very easy to lay. Often set in a concrete base as a deterrent paving. Low maintenance, but can be slippy when wet.

Manufactured materials
Paving Type	Description	Comments
Concrete flags/slabs	Pre-cast slabs of concrete	Flags/Slabs are usually either wet-pressed or moulded rectangles. Utilitarian. Available in various colours or other shapes. A good range of sizes and reasonably priced. Can be used very effectively. Reclaimed and new are available. Their end use will determine the laying method most suitable.
Concrete patio flags	Decorative flags	There is an enormous range available from local builders merchant, and a price range to match. Choice of colours and shapes. Tend to be sized more towards the home handyman than the construction industry, typically around 450x450x35mm. Three common types: Textured - the surface of the flag has been treated to alter the usual surface appearance, such as a smooth-ground finish or coarse-grit finish. Decorative - these flags have an enhanced surface appearance, for example, an exposed aggregate, or a flag moulded to imitate old bricks or cobbles. Riven - The artificial or reconstituted copies of natural stone flags. Vast range of choice, price, aesthetic appeal and, of course, price.
Porcelain Paving	Kiln fired tiles	Similar to floor and wall tiles but significantly thicker and created specifically for outdoor use. Exceptionally hard and strong, with a wide range of hues and textures to suit almost every taste and budget. Very low water absorption which helps them remain cleaner for longer, but also presents specific challenges for the installer.
Concrete block paving	Concrete Bricks	Blocks of high strength, hydraulically-press concrete. Not usually much bigger than 250x200mm. Mass production has kept costs low, and the range of colours and shapes allows fantastic creativity. Must be laid correctly. For drives, paths, patios and just about anywhere else a quality pavement is required. Low maintenance. Three common types: Modern rectangular - as seen all over the country. 200x100mm rectangular blocks usually laid in a herringbone pattern. Very, very popular. Huge range available. Tumbled or Antique Block - These blocks are shaped and/or treated to re-create a natural, sett-like block. Can be very attractive, especially on older properties, and are cheaper to install than real setts or cobbles. Good range of choice for sizes and colours. A little more expensive than the modern rectangular blocks. Shaped Blocks - These blocks are special shapes that form an interlocking pattern. Hexagons, octagons and many other shapes are available in a wide range of colours and sizes.
Clay brick paving	Clay bricks	Kiln baked bricks usually 200x100x65mm, but other sizes available. These bricks are usually laid in the same manner as their concrete cousins above, but the colours are truly vibrant, the bricks extremely hard and because of the natural variation of the clays used, are more natural looking. A vast range of colours available (think of all the different house-brick colours you see each week!) and recent developments include thinner bricks for domestic use and very small units - clay cobbles 65x65x65mm. They can be difficult for the home handy man to work with. More expensive than concrete blocks, but they should be considered, as their aesthetic appeal is worth a few quid more! Can be prone to mosses and algae - see maintenance and cleaning. The laying of clay paviors is usually identical to that for concrete blocks, and the two types are covered in one page. However, clay paviors are also used to construct 'rigid' block pavements, which are described on their own page in the block paving section. Brick paving picture guide
Permeable paving	Permeable concrete blocks	Permeable pavings have become popular in the last few years as a potential solution to the vexed problem of storm water run-off, aquifer depletion and over-burdened sewers. Although their use is predominantly civic, industrial and commercial projects at the moment, it is expected that permeable paving will become the default specified option for all sorts of schemes in the coming years.
Specialised paving	Deterrent, Tactile, and Safety Paving	A group of paving units that have been developed to perform a specialised function, be it deterring pedestrians and other highway users, alerting the visually handicapped to hazards, or cushioning the fall of a child in a playground. Not much demand in the residential paving market, but more and more common on commercial and civic schemes, especially since the introduction of Document M of the Building Regulations
Grass paving	Reinforced Grass	A variety of systems that enable grass to be incorporated into a pavement capable of being trafficked. Popular for those areas where vehicle access is only required occasionally, such as fire appliance access and parking areas in rural settings. Some systems can also be used as erosion controls.
Cellular paving	Cellular Systems Geo-matrices	Plastic cells that can be laid on top of a prepared bedding layer and filled with gravel, bark or other loose fill to form a remarkably strong surface. Alternatively, they can be filled with a soil-sand mixture and turfed to form a traffickable surface.
Pattern imprinted concrete	Coloured patterned concrete	Also known as 'Stamped Concrete'. Bays of concrete to which a colour is added and a pattern, such as brick or stone, is imprinted into the wet concrete before it sets. Can be quite impressive or can look appalling! More than any other paving type catalogued here, this type of paving is unforgiving. Mistakes are hard to put right once the concrete has set. Low maintenance. Can be expensive, seems to be sold using the same tactics as those used by our friends in the replacement window trade. MUST be done by competent tradesmen.
Plain concrete hardstanding	Plain concrete	Bays of mass or reinforced concrete. May be tamped or float finished. Utilitarian. Cheap. Easy to lay, hard to get rid of. Not visually appealing but it certainly has its uses for those areas where a cheap, low maintenance pavement is required such as for caravan storage or for kennels. Also used for garage or shed bases.
Tarmacadam Bitmac	Tar-coated aggregates	Ubiquitous. Bituminous macadam to give it its full title, is laid hot and rolled smooth. OK for roads, drives, larger footpaths and forecourts. Not suitable in gardens, where it is rapidly attacked by mosses. Vulnerable to oil or petrol spillages which dissolve the binder. Relatively cheap, usually black in colour but also available in red and even green!
Resin bonded and resin bound aggregates	Small pebbles	Decorative aggregates, set into a transparent epoxy resin matrix or onto a coloured resin-coated substrate. Usually laid over a suitable base, typically concrete. Must be laid by a professional company. Good range of coloured aggregates to choose from. Can be expensive.

Associated Topics

There's lots more information on these other pages, each dealing with one particular aspect of the groundworks trade. Use the links below to see more.....
Aggregates for Paving British Standards Cutting Paving Materials Drainage Ducting Edgings & Kerbs L'scape Fabrics & Geo-Membranes Landscape Features Mortars & Concretes Pointing & Jointing	Repair & Maintenance Setting Out Tools Specifications Sub-bases Sub-grades Screeding Buying Paving Materials Finding a Good Contractor Working Safely

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