Although there are regulations to control the size and density of a lot parcel thereare none that effectively control the actual shape of the lot*.
As a result many land subdivisions will almost always have a few lots that are a very unusual shape. As a designer this presents a challenge that is irresistible however, to the property developer it represents inefficiency given the ultimate impact of planning controls on the building footprint.
Planning controls are an important design constraint to help minimise inappropriate development and produce more equitable solutions for the purpose of maintaining high living standards. These controls work very well for rectilinear lots but introduce inefficiencies when applied to triangulated lots.
The most impactful controls are Setbacks
The diagram below shows two distinctly different lot parcels that are exactly the same size and with an identical building footprint. Lot A is rectilinear and the building footprint more than adequately fits within the setbacks whereas the building footprint within lot B does not.
Yes, a design can easily be created to make the building footprint fit within the setbacks for lot B however, it will mean introducing more complexity into its structure, construction technique and logistics which in turn will increase building costs.
There are other planning controls also to consider including privacy or overlooking, wall height and length which will impact the building footprint further.
*Some local authorities may impose specific criteria for land development in their locale.