There are two main A-D-U construction categories; custom A-D-Us and prefab A-D-Us. Custom means that it is uniquely designed to fulfill the homeowner’s design preferences. Prefab is prefabricated at a factory location off site and then assembled on the property. Either option is not cheap. One might imagine that prefab accessory dwellings would cost much less than custom, but this is not always the case. In fact, prefab A-D-Us can cost much more per square foot than even custom built dwellings.
In addition to custom and prefab options TRUPLANS has introduced a third A-D-U category we call prespec. The prespec A-D-U is a cost effective option to both custom and prefab and is being introduced under the TRUSPEC-A-D-U brand and trademark. TRUSPEC-A-D-U is an accessory dwelling unit that has been fully pre-designed, pre-specified and pre-packaged making them more adaptable & affordable than custom or prefab.