A 300mm pod with 85mm of concrete above is used in an H1 slab. A 300mm pod with 100mm of concrete above is used in an H2 slab. A 400mm pod with 110mm of concrete above is used in an H3 slab.
The number indicates the height of the slab in inches above floor level. The letter indicates the depth of the slab. Slabs are usually placed 4 inches (10 cm) or more below the top of the footings to allow for construction work around them. However, slabs can be set closer if special care is taken at job sites to avoid damage.
An H1 slab is about 1.5 feet (0.46 m) thick. This type of slab is suitable for loading areas like truck scales and other heavy equipment. It can also be used in applications where a thick slab is needed to protect something underneath it like a kitchen floor.
An H2 slab is 2 feet (60 cm) thick. This type of slab is used in applications where a thicker slab is needed to support large objects like furniture. The H2 slab is also called a "kitchen slab" because it provides a flat surface on which to place the kitchen countertop.
An H3 slab is 3 feet (1 m) thick.
Concrete slabs supporting lesser weights, such as walkways, patios, and shed bases, should be 75-100 mm thick, while driveways and garages should be at least 100 mm thick. Commercial-use slabs should be at least 175 mm thick and reinforced. Thicker slabs are needed to support greater loads.
The depth of concrete sets off how much it will cost to build your slab. The amount you'll pay depends on the size of the slab, but it's almost always less per square foot for larger slabs because more of them go into one job. The total cost of the slab also depends on its quality and the type of reinforcement used to make it stiffer or more flexible. Reinforcement is the material that gives concrete its strength, and there are several types available: steel bars for high-strength slabs and wire for cheaper options.
The best way to decide how deep to pour your slab is by looking at other parts of the house and building code requirements. For example, if you are laying a garage floor, then it must be at least 1.5 meters (5 feet) wide and long enough to contain your vehicle. That's why garage floors are usually poured in panels that are later joined together with mortar or adhesive.
Concrete is normally placed at a thickness of 2 inches or greater, however the thicker the concrete, the stronger the slab. A slab is typically four inches thick. Driveways, pathways, slabs, and footers are examples of thinner uses. Sometimes these items are called "cookie-cutter" surfaces because they can be cut to fit any shape needed.
The strength of concrete depends on how much water it has access to while drying. The more access it has to water, the weaker the concrete will be. If it's exposed to air, then rain will continue to wet the surface and allow for further hydration, which makes the concrete even more weakly tied together. Concrete that is fully cured (dried) under normal conditions will usually be strong enough for most applications. However, concrete that has not fully cured may appear sound but will deteriorate over time as the remaining moisture within the material causes corrosion of any metal inserted into it such as rebar or drainage pipes. This corrosion can lead to other problems such as leaking where metal meets metal.
The type of aggregate used in concrete plays an important role in its strength. Natural aggregates such as rock or sand are used in most building projects due to their cost effectiveness. They provide bulk to the concrete while allowing space for the cement paste to properly cure. The larger the particle size of the aggregate, the less likely it is to penetrate the cement paste.
The concrete slab should be at least four inches thick; it should be thicker if heavy machinery will be resting on it. Building codes specify the concrete mix, which varies by area. The criteria are described in terms of "compressive strength," which is essentially the quantity of water in the mix. The higher the compressive strength, the better.
The type of reinforcement used in the slab affects its durability. Reinforcement includes wires or bars that give the slab its strength and keep it stable. There are two main types: rebar for concrete floors and walls, and mesh for ceilings.
Rebar is woven into the concrete while it's wet to provide extra strength. The length of the bar determines how deep it goes into the slab. For example, 6-inch-diameter rebar goes about 2 inches into a 4-inch-thick floor. Ceiling rebar is usually only as deep as needed to reach the top plate of the ceiling. Then another piece of rebar is added on top of that. This process is repeated until the entire ceiling is reinforced.
Mesh is a network of wire strands placed between the ceiling and roof panels of a garage to prevent objects from falling through. The thickness of the mesh depends on how much weight will be supported by it. Garages tend to support some degree of traffic movement and typically have a suspension system to reduce vibration when vehicles enter or leave the garage.