This section is a brief overview of the steps involved in constructing a waffle pod concrete house slab. This overview leaves out certain steps for example engineer testing the soil will generally happen weeks before the slab is designed. Planning of the slab and material purchase will change from job to job. Concrete house and building slabs are a significant part of the cost, this overview attempts to give a general outline of where the costs are.
1. A site is cut to near level with a bulldozer, drott or backhoe.
2. The surveyor set pins in the ground to mark out the floor area and give tradesmen points to measure from.
3. Plumbers and electricians dig trenches to lay pipes and services for bathrooms and kitchens, that are under the slab.
4. Concretors arrive. using bobcats and excavators we dig footings and piers to engineer specification and level the site using laser level tools.
5. We fill the footings and piers with steel cage.
6. We then erect temporary formwork or boxing as it is commonly called. This will provide the shape of the slab and hold the concrete while it dries.
7. We lay plastic to prevent the damp rising and ground moisture, we then lay waffle pods, this provides the slab height and creates ribs/beams between the waffle pods which will be filled with concrete and provide strength.
8. We lay heavy steel bar in the beams between the waffle pods creating a bottom layer of criss-crossing steel.
9. We then lay top steel mesh, raised on chairs on top of the waffle pods.this holds all the concrete together.
Note- The engineer designs of house slabs are very thorough and there is plenty of strength. Footings, bottom and top steel as well as extra steel in corners and other structural areas combine to create a very rigid durable structure.
Pouring the concrete is another process. Due to the nature of concrete, to provide a slab that fits engineer specifications it must be completed in one pour. Basically once you start you have to keep going rain, hail or shine. In wet weather this will extend the finishing time, in hot weather it accelerates it. Pouring the concrete slab is basically non-stop work until it is finished.
1.We set a laser to give us a finished concrete height. usually 85-100mm thick.
2. We use a pump with a boom to place the concrete, vibrating tools ensure the concrete settles everywhere it needs to be.
3. We use the laser level to set concrete height pads, we use a screed to join the areas between two pads, this gives us a benchmark to work to. We use the screed between two benchmarks to level and smooth the concrete.
4. We use various other tools in further steps to gradually smooth the concrete surface and close the pores and imperfections in the concrete as it dries to give it a smooth flat finish.
5. A concrete trowel machine or “helicopter” is used to further smooth and close the surface.
6. The last step in finishing will be to “water wipe”. When the concrete is very close to fully dry we use a hand trowel and water bottle to go over the entire area by hand to give the perfect finish.
8. While the finishing stages are occuring other workers will be removing the formwork, cleaning and re-loading it back on to the truck.
Pouring concrete can be very tough work, especially in the summer. Its all hands on deck as the concrete can go off very quickly and there is no time to rest until it is finished. There will be workers finishing the concrete while others remove the boxing, its up to the skill and experience of the tradesmen to “read” the concrete and decide when to complete the needed steps. Its important to get it right as there is no second chance with concrete, once its hard, thats it. Everything can get hectic, but our experience and systems ensure we get it right.
As you can see there is quite a lot of steps involved and all the material and costs add up. surveyors, machine operator, concrete pumps and the concrete itself are all expenses that must be taken into consideration. Not to mention the manpower needed to complete the work correctly, its impossible to do this job without experienced men on the job working very hard. Finally the concreters skill, training, insurances materials and equipment usage are all things that must be accounted for. The basic amount for a vehicle and the tools to complete house slabs are close to a $100000 investment alone.
Considering all this, concrete is one of the most cost effective building options. The longevity and durability of concrete as well as its ability to be formed into shapes for many applications and its multiple uses make it an outstanding investment. Concrete construction may be something you only need to buy once, make sure you get someone who does it right the first time.
Call Brisbane Concrete for the best quality work at the best price.