Delivery of sand - the top layer of fill

Filling and Compacting

Andrew Kerrby author page

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Wednesday June 17

Getting down and dirty

For a slab on ground construction such as 60k House, the concrete slab needs to sit on a solid, level base. Because the site is on a slope we needed to raise the level of the base within the perimeter blockwork with fill. The excavator was used to remove the layer of top soil and clay. It had rained over night so we also bailed out the water that had become trapped by the blockwork and collected at the low point. Another task was to knock off the backs and sides of the knock-out blocks with a sledgehammer.

 

Preparing to fill: bailing out the water, removing the topsoil and knocking out the knock-out blocks

Preparing to fill: bailing out the water, removing the topsoil and knocking out the knock-out blocks

 

A layer of gravel was then scooped in to provide the bulk of the fill.  On top of the gravel went a 200mm layer of FCR (fine crushed rock/blue metal).  Finally a 50mm layer of sand was spread evenly on top. Notice that each layer of material is much finer than the previous one. Each layer needs to be compacted before adding another layer on top (this minimises any settling or subsidence that cause the concrete slab to move or crack). To compact the materials we used what is affectionately known as a ‘whacker packer’ (compactor).

 

Luke on the 'whacker-packer', compacting the gravel fill

Dirty, loud, shaky work: Luke on the ‘whacker packer’ compacting the gravel fill

 

The 'whacker packer' sits silent as the sand waits to be spread across the FCR

The ‘whacker packer’ sits silent as the sand waits to be spread across the FCR

 

Because of the area of the concrete slab a strip thickening is needed to strengthen the slab – an additional footing to the one around the outer edge. The thickening will reduce the likelihood of movement in the slab that might cause it to crack. The thickening is not exactly in the centre but will sit below a masonry wall made from recycled bricks – heavier than a standard timber framed wall.

 

Forming the concrete strip thickening in the middle of the slab

Forming the concrete strip thickening in the middle of the slab

Plumbing

The plumbing that will be within or beneath the concrete slab also needs to be installed at this time. For 60k House only the plumbing for the bathroom will be below the floor; the plumbing for the kitchen will be within the wall cavity and can be done later once the walls are framed up. The plumbing work is done by a licensed plumber and the location checked by a council plumbing inspector.

 

Digging the trench for the plumbing

Digging the trench for the plumbing

 

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Craig the plumber installing the pipe for the floor waste to the shower/bath

The end of a long, wet day

This was the first wet day we had while working on site. At this stage of the project, with not even a floor to stand on or a roof to hide under, cars and trees were the only shelter available. However at the end of the day and with the first piece of floor insulation in place Greg the builder still managed a smile 🙂

 

Is that a smile? First piece of floor insulation in place

Is that a smile? First piece of floor insulation in place

 

Costs: gravel – $448; FCR – $544; earthworks – $500; plumber – $399

 

Disclaimer: Any advice contained within this blog is of a general nature only and cannot be relied upon. Details provided are in good faith and relate specifically to this project. Any author will not be held responsible for advice or information presented.

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