If you want to use the ground floor rooms “Lojas” for additional living space you will no doubt be considering how to gain more head room. You could lift the first floor height. That would make the top of the windows lower which ruins the views for taller people. Or you could dig out the floor which is what we are showing here. You may be lucky. The floor could be only animal manure a meter deep so it will be easy to dig out and good for the garden. Most of us are not so lucky and it will probably be compacted soil and boulders. In extreme cases it will be solid rock. The people who built the house would have chosen a piece of solid ground to locate their house which is why its still standing and also why digging downwards is a big job. This is one area that I recommend you leave to professionals.
Depending upon the individual situation it may be best to use a concrete waterproofing agent, a black polythene sheet DPC or a more engineered product such as oldroyd tanking system. In the most extreme cases you will need to lead away from the property any running water particularly as in this case with water running even in the summer.
Don’t be put off. With careful execution you can cheaply create additional living space in what were unused areas.