There are many factors that affect the affordability of a new house including size, shape and construction methods.
Labour is a major cost of building a house or any other structure – along with materials and components. The more you can do yourself the cheaper the cost. Before the industrial era, it was normal for people to be involved in building their own house and it provided the satisfaction of achievement and self-sufficiency. Depending where you were there may not have been any professional builders in the area. Houses and building techniques were much simpler and most people had the rudimentary skills to build a homestead, either alone or with help from the community.
These days, houses are very complex systems. they are usually highly technical and require specialist knowledge to construct. On top of that there are many regulations that need to be adhered to and local authorities may require the sign-off of a registered builder to get the building consent approved.
Do what you can yourself
Notwithstanding these factors, and even if you don’t have any building skills, there is still a lot you can do. Project management, labouring, building site maintenance, picking up supplies, waste removal, plastering, painting, landscaping and so on. You could potentially save 50%, or more, of the overall labour cost by doing it yourself and with the help of family and friends. More hands make light work.
If you also source cheap materials and components yourself, you could save a significant amount of money. As discussed here, the house building industry involves a long and complex supply chain with different suppliers and contractors adding a profit margin, as well as middlemen clipping the ticket. There might be ways to circumvent this by buying from online marketplaces, buying second-hand or direct from a local manufacturer or wholesaler.