Construction Design 1
Walls Up To DPC
Once the foundations have been
completed, it will
usually be left for around two weeks. This is because concrete takes
approximately two weeks to cure to full strength (depending on the weather), so
once the concrete is poured nothing will happen for some period of time while
curing takes place. During this time the builders will often work on another
plot.
Once cured, walls will be built
upon the foundations up to the DPC (Damp Proof Course). The construction of
external walls in domestic housing takes the form of cavity walls which are
walls built from an outer leaf of brick and an inner leaf of blockwork. The
inner leaf, sometimes called 'trench blocks', are the structural element of the
wall, whereas the outer leaf is the weather-protecting element. The
cavity prevents water from reaching the inner skin and improves the thermal
efficiency of the wall, as the air in the cavity is a good insulator.
The soil taken from the trenches will return to fill the space left next to the lower walls. The outer leaf walls up to DPC are made up from around four layers of blockwork below around five layers of bricks. The transtition from blockwork to bricks will occur below the intended ground level, to give a clean finish, and the impression that the intire wall is constrcuted from bricks.
The diagram above shows a house on the site where the ground level changes. Here, a stepped trench will be used, and the bricks follow the same line.
The provision of services to a house requires various different methods of entry - mains cold water is required to be 750 - 1350mm below ground level to protect it from the effects of frost heave. The pipe only rises when it is inside the house, where it is protected from frost. In order to accommodate the floor slab, the pipe has to enter the building inside a larger pipe, in this case the orangey-brown one. The mains electrical supply will enter the building elsewhere.
Of the houses built up to DPC level on the site, all of them had special ventilation openings. These work in a similar way to weep holes which allows any moisture that rises or falls to the DPC to escape. It is essential that this moisture escapes so that it can not harm any wood or other porous materials in the house.
