They are often made of high tensile steel that has difficult welding characteristics, and if not modified carefully sets off chain reaction corrosion.
The have extreme duty corrosion protection paint and plywood protection that probably emits toxic vapors.
They are a brilliant economical modular unit for incredibly secure strong storage and transport but as soon as you remove doors and cut in openings they lose most of that strength.
2.4m wide is not a good dimension for creating living space, a minimum of 3m wide for any room is much more user friendly.
They are remarkably wonky and distorted when you go to fit accurate joinery and trim.
By the time you have turned a tin box into a livable unit with linings and trims, you have an inferior compromise for a price that isn't really economical.
They might be a poverty pack entry level for disadvantaged clientele.
If you are purchasing used shipping containers for your home, it is important to understand that these containers were designed for a lifetime at sea. The wood flooring on most shipping containers includes heavy pesticides to deter rats and rodents from eating through the flooring. Furthermore, the paint on these containers often contains chemicals to protect the containers from saltwater spray from the oceans.
To avoid these harmful chemicals in your shipping container home, you can either choose to buy a new shipping container that does not have these chemical issues or make some adjustments. Consider ripping up the pesticide-infested wood flooring and installing your own flooring. Foam insulation on the interior of the shipping container will protect from any off gassing from harmful chemical paints.
I hope these excerpted answers will help you understand expandable container house.