Building a Basement

Suspended Slab

When building a suspended slab its best to prepare as much of the services and penetrations as possible without having to drill through later. In the pictures below you can see pipes and duct work for plumbing, electrical and airconditioning.

Basement Plumbing

In the basement if its not done properly water issues can cause serious damage and ongoing problems. Its not only important to waterproof but also ensure the ground water behind the walls can flow without restriction and is able to be drained away.

Here we have placed strip drain in between the concrete piling, this will create the necessary void and drainage behind the shotcrete walls.

The drainage behind the walls and under the concrete slab need to be linked to a pump station which pumps the water to the legal point of discharge. 

Above you can see the stormwater pit we also have a sewer pit installed as there is a bathroom and wet bar to be build within the basement.

As well as having a large stormwater pit with dual pumps pumping water to the legal point of discharge we have a retention system also designed in the basement for those time when its bucketing down rain and the main drainage system within the street can not keep up with the deluge of water, this allows the water to back up with in the system and not flood onto the basement floor.

Excavation

When excavating a basement you need to consider access for trucks, impact to the road, traffic management if it on a busy road and weather as rain will close most tip sites for the day. 

With access for the trucks, parked cars in the street pose difficulties when trying to reverse a truck or truck and trailer onto the site. Sometimes its best to have tandem trucks without trailers to remove the excavated earth as the street access its too tight.

 

Capping Beam

The Capping beam is a steel and concrete beam that ties all the piling together, creates the foundation for the suspended slab and helps to hold the earth and neighbouring houses back.

The steel reinforcement bars are placed over the top of the piling cages with ligs designed to the engineers specs.

Once the steel reinforcement is complete the concrete is then sprayed onto it and the capping beam is formed

Once the concrete is dry the formwork can be removed and the basement excavation can commence.

Piling for a basement

The first step onsite to building a basement is usually installing the pilling. This involves drilling into the ground around 6 meters deep and 450mm diameter depending on the engineering specs then filling the hole with concrete and steel.

Drilling the holes can be tricky when the basement is designed boundary to boundary, the fences may not be on the proper title and the machinery will not be able to get right upto the title line because of restrictions with the drilling auger and neighbouring tree branches overhanging.

Once the piling steel cages are in place they should be all lined up at the right height ready for the Capping Beam to be setup on top.