Soil testing – Site classification report
In any new home, the engineering requirements are an extremely important part of the construction process. Even more so in a multi-level home.
The first engineering report for a new home is a site classification report. The structural engineer visits the site to take soil samples. The samples are taken from several locations over the block to determine the type of soil on the block. The report will state whether the type of soil changes at different depths. It will also state if there is organic material (old tree stumps etc.) underneath.
From that initial visit, the engineer will determine the type of foundations or footings required. In the Perth area, we are lucky to have a large percentage of very stable sand sites. This minimises the engineering requirements significantly.
The engineer will determine:-
- how much compaction is required under the footings and slab
- Whether thickenings (thicker concrete or steel) are required under the internal walls,
- what type and size the reinforcing (steel) should be in both the footings and the slab,
- the slab and footings size requirements and
- whether ‘Z’ bars are required to tie the footings and slab together (these are often required in clay or active soil types).
The engineer will also determine the concrete strength and reinforcing requirements for the suspended slab in 2 storey homes.
They take into account:-
- slab thickness,
- span (distance) of any open areas,
- slab penetrations – eg, for air conditioning ducts, etc.
- and any openings – eg. stairway, etc.
Quite often they require a suspended slab to be extended to sit on an external wall to provide additional support for longer spans.
Suspended slab – preparation and pour
Completion of the ground floor brickwork with the appropriate strength bricks to the ground floor ceiling height is the beginning of the preparation. A safety rail and work platform are put in place by the scaffold team. Formwork is then cut and placed to all the areas required with vertical bracing to all perimeter sections. The base of the stairs are also placed at this stage along with any penetration block outs for air conditioning, etc..
The reinforcing steel is placed according to the engineer’s details which are very specific to the loads and spans.
When the steel is fixed in placed the stairs are formed up and the plumbing and electrical prelay pipework is completed.
The engineer inspects the finished form work and steel fixing before the slab can be poured. Once they have inspected the works, they sign it off as OK.
Once the preparation works are complete, the concrete is poured with a boom pump to lift the concrete from a hopper to the slab area. The concrete is vibrated as it is placed to eliminate any voids or holes. This is also to ensure the correct strength is achieved. The slab is trowelled off to the specified requirements and then left to cure. In warmer weather we place a chemical curing film over the slab to ensure slow down loss of moisture as it cures.
Central Avenue Homes, generally allows a 3 course suspended slab with dovetail battens cast in to the underside of the concrete. The battens allow us to fix a continuous plasterboard ceiling throughout the ground floor. This provides a superior finish to a ‘skim’ coat with wet plaster. In addition, the 3 courses of concrete provide extremely high thermal and acoustic properties. It also provides more depth to run electrical, data and plumbing services. These services are becoming more comprehensive as clients want to keep up with changing technological requirements.
Completion and build to lock up
Central Avenue Homes have been building custom designed homes for more than 20 years and homes to lock up since 2004. Building to lock up is not a new process for us, we have built single storey, double storey, 3 storey and multi unit developments to both completion and lock up from Bunbury to Butler.
Central Avenue Homes’ office is located in the industrial area of Yangebup which is approximately 23.9km’s and 38 minutes drive from Biara Gardens Mt Claremont