Each answer narrows the next. Stop at the first one that says no.
PDM maps and the câmara planning department
Solo rústico or urbano, the category, and any RAN or REN overlay
Whether a specific house will be approved
Caderneta predial (AT) and certidão permanente (Conservatória)
Which articles exist, recorded areas, whether a building is recorded
Buildability. "Terreno para construção" can rest on a past deed declaration
Pedido de informação prévia RJUE Art. 14.º to 17.º
A binding answer for that plot, valid for two years if favourable
The condition of what is standing
Licensing file, pre-1951 certidão, recorded footprint
The last valid antecedent a reconstruction can restore
How much of it can be reused
Engineer's site visit
Walls, foundations, roof, measured footprint, later additions, water and wastewater
Planning questions: those are steps 1 to 4