Brick in the wall
Bricklaying is probably the oldest and most preferred of building methods. Here are some tips on how to construct simple structures for your home.
Note! This article is a guideline for building simple structures and not for high walls or buildings.
Whatever structure you build, if you want it to last and be safe you need to build it on a proper mortar foundation. Mortar strength is achieved by using the correct admixtures and following the correct curing process. It is a science and should be respected.
Brickwork should always be done methodically; straight and level. Also invest in or rent the right tools for the job. Few things are as frustrating as trying to get something done with the wrong tools.
The width and depth of the foundation trenches are dependent on whether the foundations are designed for a typical outside double brick wall or a single brick wall. Usually the foundation is approximately 760mm wide to support a double brick wall, and approximately 400mm wide for a single brick wall.
The depth at which it is cast depends on whether the brick courses of the new wall will have to match up with those of an existing wall, as in the case of an add-on, or on whether the area has been previously dug over, in which case the trench must be dug to a depth where consolidated soil is reached.
Finish the foundation with a wooden float to make it smooth and level.
Mixing concrete differs in certain areas and also according to the bricks you use. This should be explained and indicated on the cement packaging. For smaller batches, it is best to buy ready mix for foundations, plastering and brickwork. Below is a guideline to admixtures.
Concrete mixed for house foundations: To make 1 cubic metre of concrete, you will need: 5.8 bags cement + 0.65 cubic metres sand + 0.65 cubic metres stone.
Concrete suitable for house floors, footpaths and driveways: To make 1 cubic metre of concrete, you will need: 7.7 bags cement + 0.62 cubic metres sand + 0.62 cubic metres stone.
Mixing mortar for bricklaying: To lay 1 000 bricks, you will need: 4 bags cement + 0.55 cubic metres of sand.
Use masonry cement complying with SANS 50413 class MC 22.5X or MC 12.5. Do not use class MC 12.5X.
For smaller batches, use containers such as buckets, drums or tins. Use the same size container for measuring all the materials in a batch.
The amount of water added to a mix must be enough to make the mix workable and plastic.
TIP! All load-bearing walls or walls higher than 3.3m should be double walls (230mm).
Use a builder’s line and pegs to mark where you will start and to make sure you build in a straight line. Use your trowel to scoop up mortar and lay it evenly on the foundation along your builder’s line.
Put enough mortar down for about three bricks to go in line. Make a few indents with the trowel’s sharp edge. This helps the mortar to bed nicely on the foundation. Then push the first brick into the mortar. Level it with the trowel’s handle.
Butter the next brick with mortar on the short side before bedding it next to the last brick in the mortar and push it closer so the mortar squishes out and stop when you are about 10mm from the last brick. Then level and square the bricks with a level and the trowel handle. Excess mortar can be scooped up and used again, as long as you use it immediately.
Place each brick level by using the already bedded bricks as a reference. If you are building a double wall, instead of placing one brick at a time place two parallel with each other and butter the inside of the brick too. When you reach the end of your wall, move the builder’s line up by one brick’s height.
Place the next brick half a brick’s length from the end on a mortar bed. This will mean your top and bottom bricks will cross over so the joints won’t line up. This staggered building method makes for a stronger wall.
If you are building a double wall, you could place the first brick diagonally, which will run across the double wall. This will also create a staggered effect. Again, follow the line, carefully checking the level and squareness of each brick. Never build more than 1m in height per day. This will give the mortar time to cure properly before being put under too much stress.
If your construction includes corners, it is best to start building on a corner. Lay the first brick and then the next one perpendicularly to form the corner. Use a steel builders square to make sure your corner is exactly square.
When you lay the second course, place the next brick overlapping the bottom brick, once again this will automatically create the stagger effect in each direction.
The corners should always be built first. This forms an accurate lead for the rest of the bricks.
Sometimes you may have to cut bricks in half. Experienced bricklayers simply hit the brick with the sharp edge of a trowel to break it in half, but this is not suggested for inexperienced DIY’ers.
Rather use a brick hammer. It should break where you strike it, although the edges might be a bit rough and uneven. Alternatively, use a chisel and hammer for the same effect.
If you are building with face bricks you might want a neat cut. For this you can use an angle grinder with a diamond blade. Remember to wear gloves, safety glasses and secure the brick firmly before you start the cut.
Moisture can penetrate into a structure through bricks and it is therefore advisable to use damp proofing. This will minimise rising damp through the walls. The plastic is black in colour and 375 micron and available in thicknesses of 110,225 and 300mm.
The best way to lay it is about three courses above ground level. Excess plastic can be cut when the construction is complete.
The crevices between bricks can be cleaned by scraping of any excess mortar from the bricks before the mortar sets. A piece of metal, cut to fit neatly between the two bricks, can then be used.
It is preferable to use wooden scrapers and stiff fibre brushes to avoid damaging the bricks, but where chemicals are to be used, the brickwork should be thoroughly wet with clean water to prevent it absorbing the chemicals and rinsed thoroughly with clean water afterwards. Try to protect adjacent features, such as metal windows and the area at the foot of the wall, from splashing.