Materials to Construct Garden Paths and Patio Designs
All, no matter how simple, require a selection of tools and materials, as well as a fundamental knowledge of the basic construction principles involved. If you have undertaken DIY projects previously, you probably already have most or all of the necessary equipment in your tool bag, and you should be accustomed to much of the terminology used by builders. If not, it is essential to familiarise yourself with the basics and to ensure that you have all the items required before starting work.
Materials to Construct Garden Paths and Patio Designs
There is a fairly wide range of materials that are suitable for the construction of paths and patios, and many of these materials are discussed on Patio Designs and Garden Paths – Construction Materials. A number of them are simply laid on the ground or on a base of soft sand, while others, including bricks, blocks, concrete and timber (if used for steps) demand specific construction skills.
Bricks and blocks
Bricks and blocks are available in a vast range, and all may be used to build paths, steps and patios. Clay, concrete and calcium silicate bricks and blocks are all perfectly suitable for the construction of steps and patio walls, while special pavers (which are made of clay or precast concrete in a range of colours) are often preferred for patios and pathways.
While there is a huge variety of block sizes, bricks are relatively standard in their dimensions, ranging from about 222-230 mm long by 106-112mm wide, and about 70-76mm thick, depending on where they are made. Facebricks, which are not meant to be rendered, are generally slightly thicker than stock bricks, which are usually rendered with mortar. Paving bricks, which normally have a lightly textured surface, are considerably thinner, and can be as little as 40 mm thick. In addition to flat-sided pavers, concrete units are sometimes moulded into shapes which enable them to interlock. These are particularly suitable for driveways which will take reasonably heavy traffic or which are built on a slope.
In spite of minor differences in size, you can estimate quantities for building or paving based on the assumption that you will need 40-45 bricks or pavers to lay 1m2 of paving, 50-55 bricks to lay 1m2 of half-brick walling (one brick-width thick), and 110 to lay 1m2 single-brick walling (two brick-widths or 222-230 mm thick).
Concrete and mortar
Both precast concrete and concrete cast in situ are immensely useful for the construction of paths, steps and patios. Concrete is also used on occasion to form the base slab for patios, particularly if they are to be tiled or topped with materials like crazy paving, slate or marble.
Mortar is used in most projects, for laying brick steps and for any stairway or patio walls, as well as for some types of paving. It is also used for screedingthat are to be topped with tiles as well as for rendering some brick and block structures, including steps.
Reconstituted stone flags and precastare popular and practical options for patio floors. These materials are cast in the factory to a variety of specifications, and as they are simple to lay, they are particularly suitable for the DIY builder.
Interlocking blocks for terraces and retaining walls are a less usual but nonetheless versatile option for building steps. They are manufactured in a range of designs, although availability varies from place to place. The shape of each unit will also determine how it is used. Some types must be laid with the open surface uppermost, which means you will need to fill the block with soil or, preferably, concrete to create a level tread. Alternatively you may top the finished step with a precast tile or slab, or perhaps a simulated sleeper. It may be possible to lay modular units on their sides, creating a smooth, solid tread. If this is possible, it is wise to shovel mortar or soil into the hollow, central section of each one.
Concrete cast in situ is one of the most widely used materials for both paths and driveways. It is also a popular option for steps, and an essential material for patios that require a solid sub-base. Made by combining cement, sand and crushed stone (or coarse gravel) with water, it is a versatile and economical material, but one which takes considerable time and effort to mix and lay.
There are several possibilities when it comes to purchasing concrete. You can buy the dry materials in bags, premixed and ready to be combined with water, or separately for mixing by hand or in a concrete mixer, or you can arrange to have it delivered ready for use. Ready-mixed concrete is only a feasible option if a large volume is required, and the premixed dry materials are not economical unless very small quantities are called for. For this reason, most DIY builders opt to buy all the necessary constituents individually and to mix them themselves.
You will need to use a concrete mix suitable for the project you plan to tackle. This will depend partly on the nature of the project, as well as on local conditions and the quality of the materials used. For instance, a 1:3:6 cement:sand:stone mix is suitable for most garden foundations, provided a relatively fine, well-graded aggregate is available; however, the crushed stone sold in many parts will result in concrete which is too stony, and in this instance, a 1:4:4 mixture is preferred. For paths, steps and exposed slabs, a stronger 1:2:3 or 1:3:3 mix is recommended.
If concrete is ordered ready-mixed, you will need to give the suppliers details of your project so that they can determine the required strength of the concrete and thus the kind of mix they will need to prepare for you.
Mortar, made by mixing cement and sand with water, is used to bond bricks or blocks and give the structure, paved surface or edging maximum strength.
Just as cement, sand and crushed stone are mixed in different ratios for concrete, so too are the cement and sand used for mortar mixes. Generally, it is acceptable to use a 1:4 or even a 1:5mortar mix for brickwork or paving with clay bricks. If concrete bricks or blocks are used, it is best to make up a weaker 1:6 mixture which is consistent with the building units used.
Cement is a very fine grey powder used to make both concrete and mortar, and as such is one-of the most important ingredients in just about every building project. Several types are suitable, but ordinary Portland cement is used worldwide. It is sold in bags of 50 kg (and sometimes 25 kg, 40 kg or 45 kg).
Cement hardens when it is mixed with water, and it is this chemical reaction which gives concrete and mortar their strength. It is worth remembering that cement will not gain full strength if it dries out too quickly, so concrete and mortar should be kept damp while they set and cure.
Bear in mind, too, that unless cement is stored away from moisture, it is likely to form lumps and become unusable. Stack it in a dry place above the ground, and use it within two to three months. Discard any cement that has become lumpy or hard.
The quantity of cement needed for any project will, of course, depend on the strength of the mixture required.
When using a 1:4:4 ratio, you can base estimates on 4-1/2 – 5 x 50 kg bags of cement being enough for each cubic metre of concrete; for a 1:3:6mix, you will need four bags, six for a 1:3:3mix and eight if the ratio is 1:2:3.
Sand is an important ingredient in mortar, both for bricklaying and for rendering brick and block surfaces, and it is invaluable as a bedding material beneath all types of paving. Furthermore, the properties of the sand used to make concrete will have a marked effect on the final product.
The best building sands are evenly graded with particles of various sizes, no bigger than 4.75mm, and with 4-5% of the sand consisting of very fine material, sometimes referred to as fines. Poorly graded sand will produce concrete which is difficult to work with, while a lack of fines will result in a mixture which is hard to compact properly.
While the source of the sand you are using is not necessarily a reliable guide to its quality, it is worth knowing that natural river sand is generally clean and free of clay, and pit sands are usually well graded. Crusher sand, manufactured for building purposes from crushed rocks, should be of a suitable quality for concrete work, but crusher dust is too fine. Beach sand contains shell particles and salt, and unless it has been professionally washed, should not be used; mine-dump sand and fine, wind-blown sand from desert areas should be avoided.
In addition, the sand used for making concrete should be reasonably coarse (‘sharp’), while that used for mortar and plaster should be softer, with more fines. When flexible paving is laid, the sand used beneath the bricks should be coarser than that used to joint them; coarse river sand is suitable.
In some areas, suppliers add lime to sand and sell it as ‘plaster sand’ (as it is used to make mortar for plastering or rendering brickwork), ‘mortar mix’ or ‘lime sand’. In this case, additional lime is not required (see below).
Sand is sold in bags of 50 kg (or sometimes 40 kg) by builders’ suppliers and moststores. If you want a large volume, it is best to order in bulk; the smallest quantity most merchants will deliver is half a cubic metre. Sand delivered in bulk will be dumped outside your house; if you live in a windy area, cover it as soon as possible with plastic sheeting to prevent it from being blown away.
Stone, the coarse aggregate in concrete, is screened to size specially for construction purposes. In some areas natural pebbles and pea gravel are available, otherwise you will have to use crushed stone, supplied in ‘single sizes’. For DIY purposes, 19mm (sometimes termed 20 mm) or smaller 13.2mm stone is ideal. The smallest size commonly available is 9.5mm (or 10mm). While it is true that the smaller the stone, the easier it is to work with the concrete, you will need more cement for the concrete to gain the same strength, and this will also make it more costly. All quantities recommended here assume that you are using 19mm stone.
Like sand, crushed stone is usually available from builders’ suppliers and stores that stock DIY tools and materials. Alternatively, this material may also be delivered in bulk. Your choice will depend on what sort of quantity you require.
Lime is a useful ingredient which makes mortar more workable and aids water retention, and should always be included in the mix if the sand lacks sufficient very fine particles. Since it improves the plasticity and cohesiveness of the mortar, the addition of lime will make it easier to render a surface and will improve bonding between bricks and mortar. It will also help to prevent the rendered (or plastered) surface from cracking. Available in 25 kg sacks from builders’ suppliers and DIY stores, hydrated builders’ lime should not be confused with agricultural lime, road lime or quicklime (calcium oxide), all of which should be avoided.
Plasticiser is a popular alternative to lime in some areas. Normally sold in a minimum quantity of 5 litres, it is mixed with the mortar according to the manufacturer’s instructions — usually 50 ml to every 50 kg of cement.
Timber used to build pergolas and patio seating, decks and wooden steps, should be durable and structurally sound. Although you will be governed by what is available in your area, ensure that the timber has been treated and will withstand weathering.
While poles can be used to build rustic pergolas, sawn and planed timber is more commonly chosen for decks and steps. Both(from coniferous trees) and (from broad-leafed species) may be used, although some types will be more suitable than others, and some species more expensive. Wood is graded according to its strength and appearance; buying the best quality you can afford always pays off. If possible, avoid timber that bows or twists. Also be careful of splitting, and of large knots which may cause the timber to break.
Railway sleepers and sliced logs are both useful for pathways. Since any type of timber will tend to become slippery in wet weather, it is usually sensible to alternate the pieces of wood with other materials, or to plant ground cover plants in between them.