Slab-on-grade foundations are concrete slabs poured directly onto the ground with no space between the ground and the concrete. This most often occurs in areas where the ground is not subject to freezing and therefore uplift is not likely.
There are offshoots of this where frost beneath the structure is controlled with foam insulation or hydronic (hot water) heating systems built into the slab to prevent the ground below from freezing. However, it is not normally economically favorable to use the slab on the ground in very cold climates.
The advantages of above-grade slabs are that it is a relatively inexpensive form of residential foundation, they are very strong when designed and constructed correctly, and they help block termites from entering the home. To know more about fully insulated foundations navigate to http://maxraft.co.nz/.
When built correctly, they provide very little space in the foundation for termites to intrude into the structure from below. This assumes that all pipe penetrations are properly sealed with stainless steel wool or suitable putty to prevent penetration. It also reduces the number of perimeter cracks that are vulnerable to infestation, making it easier to treat should termites enter the home.
You must carefully plan utility penetrations through the slab for water, electricity, gas, telecommunications, and any other utilities. This is often overlooked, especially as we don't account for changes in technology.
When planning a slab-on-grade foundation, you should run a conduit from below to an accessible location outside for water. Most plumbers will directly bury the line or embed the copper lines directly into the slab.