To bond bricks together, spread the mortar over the foundation with a bricklayer’s trowel, and lay a brick on top, the frog (hollowed-out part) uppermost. Many amateurs and, indeed, some tradesmen prefer to lay with the frog downwards because, they say, the mortar will squeeze into the hollow part and obviate the risk of tilting. On the other hand this may entrap a column of air which will expand in hot weather and could loosen the bond — though in well bonded bricks the danger is small.
Tap the brick gently with the handle of the trowel to consolidate the mix. Dab a little mortar on the end of another brick and place it end-on to the first. Again tap it downwards and also endwise against the first brick until there is about 9.5 mm (1 in) of mortar separating them. Continue with the remainder of that course in the same way.
Then spread another 9.5 mm (1 in) of mortar along the top of the course you have just laid and on it lay the second course, testing that it is horizontal and even with a builder’s spirit level or with a smaller level stood on the top edge of a straight board.
After you have laid a few courses check that the wall is vertical with a long spirit level. Apply these checks as you proceed — both horizontally and vertically. Work systematically. One ill-considered move and you will get a bulge, undetectable at the time but which will be noticed in the completed work and can be put right only by pulling down the whole construction and starting again.
You will be left with rather a rough bonding edge. With a pointing trowel, smaller than the one you have been using for laying the bricks, fill in gaps and finish off as you proceed to get the flush or weathered finish. The hollow finish is achieved with a length cut from a short piece of hose pipe or old galvanized bucket handle or similar tool with a round smooth end. This is called jointing.
Really first-class work requires pointing, and this is done after the wall is built by raking loose mortar out of the joints with a blunted tool and trowelling in a coloured mortar.
The best way to master the art of bricklaying so that you do it in the most efficient and time-saving way is to look at a bricklayer working. Note how all his materials are within easy reach. He takes a trowelful of mortar and spreads it with two motions only. He places a brick in position, taps it to bed it in and whisks away and throws exuding mortar on top. There are no unnecessary movements and he takes care not to stain the face of the bricks with droppings.
You may never reach his perfection; but by watching him for a few minutes you will learn more than by hours of reading several thousands of words.
It is a matter of arithmetic to work out how many bricks will be required for a job. For a stretcher bond of imperial-sized bricks of half-brick thickness (4k in) forty-eight will fill a square yard of wall face, and you will want a little over half a cubic foot of wet mortar. A single-brick solid wall (8i in) will take twice the number of bricks and slightly over twice the amount of mortar — because, in addition to bonding the bricks end to end, mortar will also be required in between the bricks that are alongside one another.
It will simplify matters, and obviate the necessity for cutting too many odd sizes of brick, if you plan the length of the wall so that it is divisible by the length of the brick you are using plus mortar thickness.
Build the ends (quoins) of the wall first. For a high wall, build to about seven courses before filling in the space between. Use a gauge rod to test the height of one quoin, so that each course you lay equals the height of the bricks at the other quoin. If you don’t do this you will come to grief when laying bricks in between. Make a gauge rod from any strip of wood marked at intervals corresponding to the depth of the bricks plus joint thickness.
To build a rectangular shed you will have to determine an accurate right angle for the quoins. Improvise a bricklayer’s square by joining three lengths of stripwood together, one measuring five units, one four units and the other three units.
Check the level of each course and also, at frequent intervals, check that the quoins are perpendicular.
After about seven quoin courses have been laid, insert a nail into the mortar of each built-up quoin and join with string stretched taut, protecting the corner with a batten. You can now lay bricks within the gap using the string to give a rough idea of straightness. At the same time, check each course by placing a board along the outer edge of the bricks.
A brick laid lengthways is called a stretcher, one laid across a header. The stretcher standard imperial bond, half-brick in width (that is, 4k in), is the easiest to lay, and is all that is necessary for low walls and sheds provided it is supported by piers bonded into the wall at every 5 m (5 ½ yds) for the former and 3 m for the latter. Note that the joins in the bricks are staggered for strength and this means that each alternate course needs half a brick at each end of the wall.
The English bond, which comprises alternate courses of stretchers and headers and is single brick in thickness is used for relatively high structures or where load-bearing has to be considered, such as in a two-storey building built solid; or where there is a lateral stress, say, in a retaining wall for a raised garden. If the garden is on much of a slope and there is a large amount of soil, you may have to go up to double this thickness. The Flemish bond, comprising alternate stretcher and header courses, is similar to the English bond and looks most attractive, but it is more difficult to lay.
The strength of a foundation will vary according to the height of a wall and the weight it has to carry.
Dig a trench to a depth of between 300 and 760 mm (12 to 30 in) and width between one and a half and three times the thickness of the proposed wall. The former may seem a lot for a dwarf garden wall, but you must get below the surface soil otherwise the structure may tilt. The latter will do for an average half-brick garage wall. In the case of a garage, check with your local authority because much depends on the type of ground on which the garage is being built. In any case, you will have to submit a plan for approval.
Dig with a slicing motion of the shovel to both sides and bottom of the trench. Rough digging only promotes a weakness in the structure.
Now shovel in concrete comprising 1 part by volume of cement, 2 of sand and 4 of shingle to a thickness of 100 to 300 mm (4 to 12 in) again according to the size of the job. Compress the surface of the mix by pulling the back of the shovel over it. Leave for a day or two to harden; then you can start building.
Checking that the foundation is horizontal can best be done, before shovelling in the concrete, by driving rough wooden or iron pegs into the bottom of the trench, one at each side at intervals, so that each protrudes to the required depth of the foundation. A board and spirit level will show when the tops of the protruding parts are horizontal. Tip in the concrete until it comes to the tops of the pegs; and don’t bother to remove them — they will do no harm.
When building a boundary wall you will no doubt want some kind of coping, not only for ornamental purposes but also to shed rain.
If you leave the top of a wall water will collect and seep downwards. In building, it is better not to have the top of any exposed structure completely horizontal. Even a so-called flat roof slopes slightly, if not all in one direction, at least towards conveniently sited drains.
Double bull-nosed bricks are used on top of a single-brick wall in the second. This still leaves a horizontal top, but two courses of creasing tiles underneath act as a damp-proof course. Half- round ridge tiles are used in the next along, with two sloping tiles underneath and an in-filling of broken bricks. The saddleback coping in the fourth is cut from natural stone or moulded in concrete. Note the drip channels underneath on each side.
The last is more functional than ornamental. It consists of a bent strip of lead, zinc, aluminium or copper. The writer has a half-brick wall with a flat top butting on to one of his house walls. It collected rain and damp trouble broke out on the adjacent inner house wall; so he used as a capping a cheaper material than metal — a roll of bituminous felt damp-proof coursing. He ‘creased’ the felt with a knife to about a quarter of its thickness so that it would fold, and stuck it down to the sides of the wall with mastic compound.Subsequent painting with venetian red bituminous paint disguised it. Oil paint would have been of no use because the black of the felt would have ‘bled’ through.
Opinion is divided as to whether or not a garden wall should have a damp-proof course at the foot, near ground level. It certainly stops moisture from penetrating up from the subsoil by capillary attraction and making the bricks permanently damp — which can lead to spalling in frosty weather — and it stops continuous efflorescence. Bricks and more particularly mortar are highly alkaline. Moisture will bring the alkali salts to the surface to form unsightly patches of white. This white can be brushed off with a stiff brush and eventually it will disappear. But if there is no damp-proof course the salts will wash into the ground and come up through the bricks again in a never-ending cycle. This is known as efflorescence. A damp-proof course will prevent it.
On the other hand, a damp-proof course forms a weak point in a wall, particularly when bituminous felt is used. Unless the piers are soundly constructed, it could be pushed over, ‘snapping’, as it were, at the damp-proof course. For this reason overlapping slates are better then felt or metal because they bond in more readily with the mortar.
Another way of preventing damp rising is to lay two or three courses of engineering bricks, which are very dense, at the foot, with common bricks on top. But engineering bricks are expensive.
Reinforcing Brick Pillars
Brick walls can be pushed over by accident or by vandals. So also can brick pillars, pagodas and free-standing gate pillars. The danger is not so acute when the centre of a pillar is left hollow. So long as the mortar holds, the structure acquires the strength of a tube or of a four-sided house. But even then departing guests, after having partaken of your hospitality, may back their motor cars into one of the pillars, and over it will go, damp-proof course or no damp-proof course, solid or hollow. To prevent this happening, drive a metre (3 ft) length of scaffold pole or angle iron into the foundation while it is still wet and build around it, filling in the centre with concrete.