Currently almost all new houses in New Zealand are built using the standard process whereby the floor and foundations are laid down, and then wall framing and roofing trusses that have been manufactured offsite are quickly erected, generally within 3 to 4 days. After that it generally takes 2 to 3 months to finish lining the house inside and cladding it outside and then fitting and finishing it. There is a bricklaying robot that can build low-cost houses in two days.
In countries like Sweden and Japan large building companies manufacturer the entire house in their Factory, using large scale automation and robots to build all the internal walls and external walls and the entire roof in such a way that the finished house can be assembled inside of one day. These factories are fully computerised, and the customer can order the entire house online by choosing one of many floor plans and selecting the colour schemes and fit and finish. This purchase process will allow the customer to walk through their house using virtual reality, and it is a very satisfying process for the customer because they know exactly what they’re getting. The manufacturer is then able to take list order and then automate the manufacturing of all the wall panels including the installation of the cabling and plumbing, in such a way that everything can be plug fitted while the panels are being put into place in a building site.
This process has huge advantages for the customer, simply because the manufacturer is very large and therefore has massive buying power in a competitive market and so gets a very large discount on all the components. Also the manufacturer has a much lower labour component for each house, and if they are building houses at a massive scale then the cost per house built is very low as apart from the materials almost all the cost is the depreciation on the manufacturing equipment and robots.
Manufacturing this way is also much safer, is the panels will be manufactured horizontally, and when assembled on site the assembly will use cranes and proper safety techniques, which means there is a vastly reduced number of onsite accidents.
There is currently a shortage of around 5000 skilled builders in New Zealand, but if the builders were simply assembling a pre manufactured house, then their work output would be massively increased, as one builder would be building dozens of houses a year rather than 2 or 3.