Building new walls for a house extension wall or a garden fence for that matter, deploys the same technique. You can have a cavity wall or a solid wall, depends on your requirements. In UK, bricks and blocks are the most common materials used to build walls. Stones, sometimes are used for special properties and walls.
The most elegant type of brick walls, and efficient too, is the stretcher bond type.
Old bricks or re-used bricks, can give the new building a more ”stable” look, because most new buildings can stand out like a sore thumb.
You could also use a variety of combinations between blockwork and brickwork.
The picture above shows a 2 storey side house extension, blockwork at the rear and brickwork on the side.
As you can see in the picture below, there is a perfect balance between the two.
If you want a more modern look, you could also use glass block, built into the brickwork or blockwork.
Remember to start building the walls on a good foundation, under the DPC is recommended to use concrete blocks, finished off with one or two layers of engineer bricks. The reason for that is the wall below the DPC is exposed to the elements and damp. Between the foundation walls, you should use a lean concrete mix, but don’t top it up, leave a gap of 10 cm for the water that might collect between the walls. Wall ties also must be used to ensure a good and strong structure.
The DPC – Damp Proof Course, is very important. It has to be above the ground level at least 15 cm and that includes any slabs or finishing materials. For the external wall, you can use the 100 mm wide DPC, and for the interior wall, you must use the 600 mm wide DPC. The overlapping DPC it will go under the DPM Damp Proof Membrane and seal the internal wall from any raising damp if the internal floor is faulty.
The wall ties must be kept free of cement, mortar, muck mix. The insulation and the muck can act as bridge between the external wall and the internal wall, thous if the external skin wall is exposed to heavy rain and gets wet, the water can travel to the internal skin wall.
Wall ties are used at a density of 2.5 per sq. metre, tie centres measuring 900mm horizontally and 450mm vertically, in a domino pattern or Z – N shape. At the corners, keep a bit of a gap.
Weep holes or “weeper holes” are small openings left in the outer wall of masonry construction as an outlet for water inside a building to move outside the wall. You must used them, together with DPC where a metal lintel above the openings can gather the water. You can use Plastic “weeps” or just leave a gap between the bricks.
Another important aspect is the cement mix for bricklaying. Never mix more than you can use, before the cement in the mix starts to set, otherwise the solidity of the wall will be compromised. Also, using to much cement in the mix can create cracks in the walls by being to rigid, because a building or any structure needs a bit of flexibility while the structure sets down, a process that can take years.
A good bricklayer can lay from 600 bricks upwards, but if you are an amateur bricklayer, 100 to 300 bricks including setting out the corners, is reasonable.
Stone walls are arguably the most ancient way of building walls. There are two types, dry walls and wet walls. In UK both types are popular, the dry walls can be used for fences and wet walls are used in combination with the cement mix.