There are a number of specific construction issues with two storey homes.
Obviously the square metre cost and length of the construction period will be greater when a second storey is added. Costs for additional storeys often double due to the cost of scaffolding, the requirement for engineering certification of the suspended slab and the need for the slab to cure for some time after being laid.
Building multi-storey is becoming much more popular than in the past. Homebuyers require a great deal of internal living space, but are increasing confined to building on smaller lots. The home is now much more a focus for activities such as home theatre viewing, entertaining in alfresco areas, or working in a home office. Buyers requirement for additional space can only be met by building an additional storey.
Two or three storey homes can also be subject to more stringent planning requirements. Issues such as privacy rights of existing neighbours or shadowing effects on adjoining properties and noise often cause rancour between adjoining property owners even before construction commences. Many local authorities require existing owners to “sign off” on building plans proposed by new developers as part of the building approval process.
Some other issues that you need to consider include what type of materials you will use for the second storey. Framed construction is becoming more popular, particular for additions and renovation activities. New water efficiency regulations impose additional requirements for homes with more than 2 bathrooms which would be commonplace in two-storey homes.