Beazley's Design and Detail of the Space between Buildings

A. Pinder

• Publisher: Taylor & Francis
• Year: 2003
• Print ISBN: 9780419136200
• eBook ISBN: 9781135921149
• Edition: 1
• Topic: Architecture
• Subtopic: Urban Planning & Landscaping

A new edition of a book widely regarded as a classic of landscape architecture, it deals with the 'bits' that go in between the different parts of the urban landscape. A completely updated text makes it suitable for both the professional and student.

Chapter one: PAVED SURFACES

This chapter deals with external hard surfaces, including private roads for light traffic. Certain notes also apply to public highways. Owing to the wide range of functions and materials that are included, it is difficult to avoid repetition, unless cross-references are included. These have been kept to a minimum as it is realized how maddening they can be, and the chapter has been organized thus:

1. notes on the functions of paved surfaces
2. list of highway engineering terms
3. notes on roads and pavements primarily intended for wheeled traffic
4. general design problems common to all paving structures
5. descriptions of individual types of pavement, by type rather than function. This means that surfaces intended for vehicular or pedestrian traffic are described together. Since the problems involved are often common to both, and since many pedestrian spaces are also intended to take the occasional wheeled vehicle, this seems the clearest division to make
6. problems of detail common to all types of pavement.

1.1 THE FUNCTION OF PAVED SURFACES

The main function of any paving, to provide a hard surface, is so obvious that its more subtle but extremely important minor functions are sometimes forgotten. It is a safe rule, though it must occasionally be broken, never to change the material without a practical reason. Changing materials simply for the sake of creating pattern, can be very precious. If the traditional use of paving materials is analysed, a practical reason can usually be found for any change of material in the surface pattern. The exception to this is of course the sophisticated patterns that are consciously designed in an area of paving e.g. the lighter stone in St Mark’s Square in Venice which, since it is not parallel with the walls of the square, reinforces one’s awareness of the plan as a whole. But such instances are rarer than one might at first suppose. In countless traditional streets and squares, market places, courtyards, college quadrangles, formal and informal gardens and parkland, on quays and wharves, in churchyards and farmyards, change of material indicates subtle change of purpose. Functions might be listed thus:

1.1.1 Practicalities

To provide a hard, dry, non-slippery surface which will carry the load of traffic asked of it; change of traffic may indicate change of material. This leads to several less tangible functions.

1.1.2 Direction

To provide a sense of direction; paving can lead and guide people who otherwise might not know which direction to choose. Particularly good examples exist in interconnecting college quadrangles, alleys and yards. One emerges from a quadrangle into a small cobbled (say) yard; there are several doors but no apparent exit, but a strip of paving flags running diagonally through the cobbles tells one which way to go. Similar examples abound of routes for wheeled traffic through pedestrian precincts. They then also function as in Hazard below. There are two things to note about their design. First, to decide on their route one must simply join the two points which are to be connected and draw a beeline between them; otherwise as direction finders they will not be sufficiently telling and urgent. Secondly, the change of colour and texture of material must be subtle, not violent. One is aiming to preserve the unity of the surface as a whole, so the contrasts must be quiet if they are not to be disrupting. The shapes left may be odd and so should not be accentuated. This also means that the background material will probably have to be rather small scale or it will be difficult to work into the acute angles and odd corners that this treatment necessarily creates. It will also be seen how fatal a last minute substitution of grass for the hard background material would be. Both visually and practically, paths across grass will need additional and different consideration.

1.1.3 Repose

To provide a sense of repose; an area of neutral, non-directional paving has the effect of halting people. In a garden that might be at a sheltered place to sit, in a town square it might be at a place to stop and gossip or buy a paper, or it may be somewhere to have a drink and gaze at a view, or rest in the shade of a tree.

1.1.4 Hazard

To provide an indication of hazard by change of material; this method, if it is used consistently, becomes a language on its own. A traditional example is the use of setts in a flag pavement where a private road or drive crosses it to reach the street. Though their origin may have been simply to provide a tougher material for carriage wheels, their presence makes pedestrians immediately aware that they are stepping off their own sanctuary—the footpath—onto a surface where vehicles may be expected. Similar use is made of cobbles between paving slabs and grass. Here they discourage people from wandering off the path, or cutting corners. A band of setts at the junction of a private and public road will not only demark ownership, but will also slow the traffic at the junction.

1.1.5 Scale

To reduce scale; this is the most difficult function to handle without making some blunder. Because there are only psychological reasons for changing materials, and the designer is not guided by practicalities, changes can easily look forced. On analysing some examples it is found that a material which is used in traditional work for a particular purpose, has been introduced simply to give pattern. Brick or slab strips in paving are an example. Originally used as a drainage channel where two sloping areas of paving meet, they are now used as dividing lines only. The subtle lines, which were entirely acceptable when a response to practical necessity, can appear either pretentious or timid (and sometimes, somewhat paradoxically, both simultaneously) when used solely as a visual device. Timidity can also sometimes be seen in another form—an assumption that any area of paving, even if only of moderate extent, has to be broken-up visually. Whilst this might be excused as a natural reaction to the seas of tarmacadam and concrete that are too often seen, if one looks at obviously successful examples it is often remarkable how simple they are. For example the whole of the middle of Sloane Square in London—2033 m² (2430 sq. yd)—is virtually paved as one area with very generous falls to the road so that there is no need for dividing up by channels; trees break down the scale, both by the vertical pattern of their trunks and by the pattern thrown by the shadows of their branches. It is in this respect, if not architecturally speaking, that it is one of the most pleasant squares in London.

A pattern of paving slabs which have scale in themselves, needs little sub-division. Macadam or in situ concrete surfaces may need to be visually subdivided. But, perhaps, consider first whether a wearing course of uncoated chippings might not give the macadam gentle colour and fine textural interest such that the very area has positive impact rather than being a daunting extent of matt-blackness. Consider also whether the expansion joints which are a technical necessity of in situ concrete paving, might not be organized in such a way as to have visual benefits as well.

When a change of material is introduced simply for the sake of scale, the change should be rather quiet if it is not to make the paving absurdly important. Paving is, when all is said and done, almost always no more than a background and should not aggressively proclaim its presence. Slight changes of colour and/or texture within the same type of material are often more successful than a change in actual material. But practical needs can be exploited for aesthetic effect. Surface drainage—a matter where one suspects designers are often plain lazy—is a case in point. It can provide an admirable practical reason for breaking down scale by the use of flat or dished channels, simultaneously giving the paving a trim appearance and a manageable scale; furthermore there is also the great advantage that they actually drain after rain!

1.1.6 Use

Ownership and use are closely related to scale. That parade grounds demand a different scale from garden paths is self-evident; the public military character of the first is so opposed to the informal domestic nature of the second. But there are also less easily defined ways in which scale can indicate such things as privacy or rights of ownership. A change from the scale of paving flags on a public pavement can suggest private property without any change of level or fencing. This device is often used at entrances to hotels and shops, or where a café or restaurant puts tables on the pavement. It has the effect of making the public realize they are on private property, which they are welcome to use as clients of the establishment, but that they are otherwise expected to move on. Generally, but not always, smaller scale paving seems to indicate private ownership; larger scale, public property.

1.1.7 Character

To reinforce the character of a particular place; paved surfaces, and particularly their edge treatments, can have enormous effect on the character of the place of which they are a part (see also section 1.17). Before deciding how to pave or detail a particular place, the desired character must be identified or, if that place is wholly new, decided upon. Is it to be formal or informal, urban or rural, crisp and precise or mossy and blurred, rugged or sophisticated? Whatever its character (and no words can ever exactly carry the synthesis in these cases) the surface must be appropriately durable and must improve with weathering. Immense variety is obtainable within quite a limited range of basic materials. From the precision of blue pavers at one end of the scale through to lichen covered stock bricks at the other; or from the rigid outline of a macadam surface edged with upstand kerbs to the informality of the same material when kerbless or a lane with grass growing down the middle. However, one must always have a clear sense of the objective before starting.

All materials must fulfil the first provision on this list—that is they must provide a useful pavement; but in respect of the other less tangible functions, no material can be said to have a single unalterable character. Its effect depends upon its juxtaposition with other materials. Granite setts, for example, provide a rougher surface texture and a smaller scale than most other materials, so they are often used as hazards, but they might elsewhere be used as direction finders within cobbles, which are even more awkward to walk on. Again, cobbles themselves are sometimes used for footpath material—they are at least easier to walk on than soft and/or muddy earth.

It must be emphasized again that really successful paving reinforces the latent or existing character already dictated by the space to be paved. In this way it can make or mar a scheme. It is not suggested that the paving alone will create character, although in certain cases this too is possible. It can be used to bring unity into what might otherwise be too diverse a design, or to give character to some rather nebulous area which needs a common background or idea. If the same material is used for all pavings, steps, plinths to buildings and free-standing walls, a motley group of buildings can be given unity and the material, be it brick, stone, concrete or whatever, appears rather as a layer in rocky country, the various levels corresponding to different strata. A sculptural effect is achieved, as though the paved area had been carved out of the whole.

1.2 PRINCIPAL HIGHWAY ENGINEERING TERMS

Each of these items and its function are described in the following text. This glossary is included here for quick reference only.

1.2.1 Pavement

(a) A general term for a paved surface (British readers should note the potential confusion in that the word is often used colloquially to refer to a particular kind of surface which, elsewhere in the world might be called a sidewalk).

(b) A term applied specifically to the whole construction of a road.

1.2.2 Flexible structures

A form of road construction which for the purposes of design is assumed to have no tensile strength. Such roads are built up of layers of granular materials. In the upper layers there is frequently a binding agent, most often bitumen or tar.

1.2.3 Rigid structures

A form of road construction in which, for the purposes of design, the tensile strength is taken into account. Reinforced in situ concrete is the best (indeed for most practical purposes, the only) example. (But that is not to say that all pavings using in situ concrete are rigid structures—soil-cement and lean-concrete bases, for example, are flexible.)

1.2.4 Subgrade

The soil (and sometimes, fill) which carries the road.

1.2.5 Formation

The surface of the subgrade in its final form after completion of all preparatory earth works.

1.2.6 Sub-base

A layer of material (which is not always needed) between the formation and the road base.

1.2.7 Base

The main load-spreading component of the road, which provides the principal support to the surfacing.

1.2.8 Surfacing

Waterproofs the road and provides a non-skid running surface. Sometimes provided in two layers, the base course and wearing course.

1.2.9 Surface dressing

Usually consisting of small stone aggregates spread on or in a thin layer of binder, but not always included.

1.2.10 Macadam

The stones which, in the original roads designed by Macadam held together because the smaller interlocked within the interstices between the larger, and which now (particularly in the base and surface layers) are often bound together with a binder.

1.2.11 Binder

A viscous material which binds the aggregate together. It may be tar, bitumen or a proprietary mix. Pigmented binders are available which can radically change surface appearance.

1.3 GENERIC TYPES OF PAVING

The above glossary might give the impression, (at least through implication) that there are only two kinds of road base construction—reinforced in situ concrete which embraces all rigid structures, and tar or bitumen bound macadam which embraces all flexible forms. It is true that all rigid structures involve the use of reinforced concrete, but even then the range of surface finishes that can be considered, and the possibility of using a reinforced concrete slab as the base to a number of surfaces which in themselves might not have necessary strength, gives this approach considerable versatility. However, tar or bitumen bound macadam is not the only generic form of flexible structures. As with Macadam’s original design, graded aggregates can be used without any binder—graded stone chippings or naturally occurring gravels are probably the commonest construction for private drives. Further, as has been said, graded and consolidated aggregates that are bound with cement but without steel reinforcement, are also flexible structures.

There is yet another form of flexible construction which is becoming increasingly common—indeed could well become the most common design approach to lightly trafficked roads. Both clay and concrete bricks can be vibrated into a sand bed ov...

Table of contents

• COVER PAGE
• TITLE PAGE
• COPYRIGHT PAGE
• BEAZLEY’S DESIGN AND DETAIL OF THE SPACE BETWEEN BUILDINGS
• INTRODUCTIONS TO THIS EDITION
• INTRODUCTION TO THE FIRST EDITION
• ACKNOWLEDGEMENTS
• CHAPTER ONE: PAVED SURFACES
• CHAPTER TWO: WALLS AND FENCES
• CHAPTER THREE: RETAINING WALLS, RAMPS AND STEPS
• APPENDIX A: REFERENCES AND FURTHER READING
• APPENDIX B: USEFUL ADDRESSES