Basic Bricklaying Techniques

There's a lot in bricklaying that you only really pick up with practice. But there are some rules which can guide you every step of the way. Understanding bricks themselves, the right way to mix mortar and how to use the trowel correctly will help you achieve a result to be proud of.

Brickwork is made up of two things:  bricks and the mortar which forms the joints. Building a wall that's going to last needs careful attention to both, and the first thing is to choose the right bricks for the job.

Know You Bricks

There are three groups of clay bricks:

1. Commonbricks have no special finish because they are made to be used where they will not be seen or be subjected to major stress or load. They are mostly used in situations where they will be covered by paint, plaster, cladding, rendering etc. They are a relatively inexpensive brick and are usually a rather patchy pink in colour.
2. Facing bricks come in a variety of colours and textures for they are made to be displayed indoors and outdoors. Also called stocksthey are capable of bearing heavy loads. If classed as ordinary quality, it means they can be used for most projects, but in very exposed conditions outdoors will need to be protected by a damp proof course at ground level (either a course of engineering bricks, or a layer of bituminous felt) or with a coping above to prevent the bricks becoming saturated with rain. Without this protection they are liable to be affected by frost which would cause disintegration. Special quality facing bricks are suitable for use in exposed places or where great strength is needed, eg for paving, retaining walls, garden walls and steps.
3. Engineeringbricks are smooth and dense, designed to be used where strength and low water absorption is essential - for example in foundation courses ( thus providing a damp proof course for a wall or planter) and load bearing walls.

Another type of bricks completely are the calcium silicate bricks. These are flint/lime bricks which are whitish when steam hardened in an autoclave (they aren't fired like clay), but these are available in many colours because they pigment well. They absorb moisture easily, so must never be laid with a mortar that doesn't contain a plasticise. They can be used in just the same way as clay bricks. Like engineering bricks, they are also more regular in shape and very less in size than ordinary bricks.

Brick Types

Bricks also vary in their character as well as their composition: they may be solid perforated or hollow, but most fall into the solid category. Even bricks with small or large holes in them (these are also known as cellular) are classed as solid so long as the perforations do not exceed 25% of the total volume. The same is true of bricks with a shallow or deep indentation known as a frog. As well as making the bricks lighter, perforations and frogs give bricks a better key(ie, the mortar is better able to bond them together). Bricks are measured in two ways: when they come from the works the actual size is 215mm long, 102.5mm wide and 65mm deep; the format size, however is the one used for calculating the number of bricks you need. This needs an allowance of about 10mm added to each of these dimensions for the mortar joints - ie, 225mm long, 113mm wide and 75mm deep. Bricks are also made in special shapes and sizes for particular uses (copings, bull nose and angles are some examples).

Storing bricks

As all bricks (except engineering bricks) are porous, they should be staked on a level area away from damp, otherwise long after you've used them the mineral salts inside the clay will stain the surface with an unsightly powdery white deposit (known as efflorescence). In the garden, put bricks on planks or a metal sheet and cover them with plastic sheeting. Apart from anything else, bricks which are saturated with water (as opposed to just being wet) are hard to lay and will prevent a satisfactory bond between bricks and mortar.

Mortar for bricklaying

Cement and sand made into mortar with water will set quickly, but is liable to create a crack between the mortar and the brick if it shrinks during drying. The ideal mortar, in fact, doesn't set too quickly, doesn't shrink much and can take up settling movements without cracking. There are two ways of making a mortar like this:

• The first is by adding hydrated lime to the mix and smooth (or "buttery" as experts say).
• The second is by adding a plasticise - a proprietary liquid or powder. Air bubbles are formed which provides spaces for the water to expand into, thus preventing cracks.
• Basic to mortar is cement. This acts as the adhesive, binding the particles of sand together. Ordinary Portland cement is the one most commonly used.
• Fine sand is used for mortar to give it its correct strength. Use clean builder's sand (also known as "soft" sand) which does not contain clay, earth or soluble salts (these can lead to efflorescence).

Buying the materials

Cement is usually sold in 50kg (112lb) bags, although you may also find smaller sizes. Sand is sold by the cu metre (1 1/3 cu yd) and in parts of a cu metre. To give you a sense of scale, a cu metre of sand weighs about 1,500kg (1 1/2 tons) - a very large heap. Both are usually bought from builders merchants, where you can also buy lime.

Mixing Mortar

1. Unless you're using dry ready-mix (most suitable for small jobs)carefully proportion 1 part cement to 6 parts builders sand.
2. Thoroughly mix the cement into the sand so that you end up with an entirely consistent colour. Turn the mix over at least three times.
3. Adding a little plasticise to the water (the amount will be specified on the container) will make the mortar easier to work with.
4. Form a crater and pour in half the water. In total you'll need about the same amount of water (by volume) as cement - but add the rest gradually.
5. Mix in the dry mortar from the inside walls of the crater. As the water is absorbed, add a little more. Turn the whole mix over several times.
6. Check it by stepping the shovel back - the ridges should be firm and smooth, holding the impression of the shovel.