Today's Explainer offers a 'foundational' overview of construction terminology. While the most visible and attention-getting stages of high-rise construction take place above ground, some of the most labour-intensive and intricate construction work takes place below grade.

Oftentimes, high-rise buildings require deep foundations, with a series of 'end bearing' or 'friction' piles digging into the soil to stabilize the structure above. However, in sites where the substrate is stable enough, another type of foundation can be employed. For high-rise buildings, a 'raft slab' provides a floating foundation to support the tower above, eschewing the use of piles. For a more thorough overview of the term, our sister site, SkyriseCities.com, offers a full explainer:

The Massey Tower raft slab, image by Craig White

In last week's Explainer, we looked at the construction work that takes place underground to support and prepare for the ascent of a structure. We touched on foundations in that post, but this time we describe a specific type of foundation known as a raft slab, as suggested by Forum member Daveography.