Successful outdoor building is a combination of careful design and the correct construction techniques. A patio combines bricklaying and related skills, to construct a variety of walls, as well as the methods of laying decorative patio slabs, for modern out-door living.
After a few days, once foundations have hardened off, the site can be set out for bricklaying. Set up a profile string in line with the brickwork outside edge. Putdown, at intervals, ‘spot’ boards, each measuring about 600mm x 600mm, made from scrap wood, to hold the mortar. Stack bricks neatly between them, but far enough away to avoid getting splashed by mortar. A total of 25 standard bricks covers an area of about one metre square.
Tools needed are a spirit level and straight-edge, a 255mm or 280mm bricklayer’s trowel, a small pointing or ‘dotter’ trowel, a club hammer, bolster or cold chisel, a wire brush, a shovel, a pair of bricklayer’s pins, and a few metres of cord.
Mortar for bricklaying consists of a 1:8 cement/soft sand mix, with one part of lime or plasticiser. This makes the mixture ‘fatty’ and more easily workable. Use slightly less sand in cold weather.
Mortar and concrete
Generally, it is either the coarse or ‘hungry’ sands which need either lime or plasticiser. The colour of a mortar can be controlled or adjusted by choosing suitable sands and altering the proportion in which they are added to the mortar mix.
Only mix as much mortar as you need at a given time and try to avoid adding water to a mortar already mixed. In hot weather it may be necessary to dampen the bricks to control excessive suction.
First spread a thin bedding course of mortar screed along the foundations, and draw a ‘course line’ along this. The first course of bricks is laid to this line. To establish the course line, place the spirit level vertically downwards on to the mortar, with its edge against the profile line. Make sure that you do not lean the level against the line, for this may cause error.
Mark the vertical line on the screed with the trowel. Repeat this at short intervals and then, with level or straight edge, join up the marks by scratching a trowel line along the mortar. Take care not to cover the line when laying the first course of bricks, as this may cause error.
The brick trowel is the most important tool used in bricklaying. Its main use is to pick up the mortar from the spot board and to spread it to an even thickness, in preparation for bricklaying.
It may also be used for the rough cutting and trimming of a brick. In the latter case, it is important to keep the fingers well clear when chopping bricks.
The choice of a trowel is an individual one, with considerations of weight, size and ‘lift’. For a beginner, a small, lightweight trowel is probably best, for a larger trowel may be more difficult to handle.
Mortar should never be allowed to harden on the blade of the trowel, for this creates a rough surface and prevents free-and-easy movement when picking up and spreading.
When a trowel handle wears smooth, it should be roughened up with glasspaper. The blade should be thoroughly cleaned after use, by washing then rubbing its surfaces with a piece of soft brick. Take care to wipe the blade well with a dry cloth to prevent rusting, and store in a damp-free place.
The first thing to acquire is the art of handling mortar with the trowel. One edge of the trowel is curved, and the other has a straight edge for ‘drawing’ the mortar off the board.
Keep the side of the mortar ‘spot’ board nearest to you clear. When drawing off mortar, the trowel is always kept at right angles to the board, with the straight edge downwards.
Cut some mortar from the heap at the back of the board and draw it towards you, maintaining a to-and-fro slicing action. This shapes the mortar into a neat, pear-shaped roll, which is taken up on the fiat of the trowel.
To do this, sweep the trowel towards you, with the leading edge scraping the board clean and the trailing edge raised slightly to trap the mortar. This should provide a fully loaded and evenly balanced trowel.
Hold the loaded trowel parallel with, and about 75mm to 100mm above the course of bricks, tilt one edge downwards, while pulling the trowel towards you with a sharp backward movement which helps to stretch out the roll of mortar on top of the bricks.
Level out the mortar with the back of the trowel, using the top 100mm from the tip. Make alternate side-to-side strokes, lifting the leading edge of the trowel slightly in each case and pushing lightly away from the body.
When the bed of mortar is about 20mm thick, tilt the tip of the trowel downwards and make a continuous furrow, parallel with and about 75mm back from the face of the brickwork. This helps to make a firm facing joint and allows the bricks to settle clown evenly.
Where there is to be a corner in brickwork, mark out another screed line, at right angles to the first, again using the stretched lines as a guide. Now put down the first strip of bedding mortar over the marked screed. Mortar for cross joints can either be ‘buttered’ on to both meeting corners of each brick before it is laid or put on when the brick is bedded down.
Form corners by laying bricks alternately on each other at right angles and build up by ‘racking back’-laying one brick less in each succeeding course.
In 115mm-thick brickwork, the cross joints should be filled completely, but in 230mm-brickwork, only the first 50mm at each end need to be filled as the laying action on the next course takes care of this. Try to maintain a uniform 6mm gap between bricks.
10. November 2011 by admin
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