As for foundations, or footings, in most cases the builder simply didn’t bother, or occasionally dug a trench about a foot (30 cm) deep, or till they hit rock. They then placed thick layer of lime mortar in the trench, into which the biggest and flattest rocks were set in, and commenced building the house walls from there. (Modern day builders and building inspectors would freak-out with horror!). Some home builders used a sand and tar mix as a form of damp-course, but many did not. Some builders used a plumb-bob to obtain vertical straightness, but most relied on their 'eye-line' to see whether the walls were going up straight, or in a straight line or, as quite often the case, anything but straight!
Floors were quite often simply rammed-earth, or a mix of earth and clay rammed (packed), down, and roughly leveled. I say 'roughly' as I have been in an old house or two with these types of floors, and walked quite literally up to the front door, or down to the back door! Some of the better constructed homes received a broken stone floor, set in lime mortar, and covered with a skim coat of strong cement of about half inch (13mm) thickness, but even these types of floors were anything but level.
From about 1880 timber floors began gaining popularity. With the importation of the well-known European Baltic Pine timber, and access to the Jarrah hardwood from Western Australia, some floors were properly constructed with sub-floor walls under the Jarrah joists, whilst other floors simply had the flooring joists balancing on loosely packed paddock stones. The original floors used hand-made blacksmith wrought nails, which were also used on all the timber joint construction.
Windows and doors. While the wealthier owners could afford to buy ready-made solid timber doors, (real solid timber too), and multi-pane hand-rolled glass windows, the poorer homes simply had hand-hewn window frames over which was stretched calico or linen to keep the flies, dust, and unwelcome visiting birds, etc, out The outside doors were hand-hewn from whatever suitable flat timber they could find, and the hinges and latch being hand-made by the local blacksmith. Interior doors were quite often simply a curtain strung across a doorway.