Damp Proofing

You need at least two air vents in the under builds to create a good air flow...this should keep the under build dry....if you are experiencing damp within your property then it's normally your fault ..do not dry clothing within the property open a window when cooking or showering ..it is necessary to open all the windows at the warmest part of the day for at least one hour especially in bedrooms / bathrooms / kitchens ..if you are using a calor gas heater / oil heater or solid fuel fire you need to  have permanent  ventilation in the room they are used in...I have been on Camposol for 12 year's ..I did have damp and mould when I first started to use my villa since I started doing what I said above ..I no longer have any damp problems.

Great advise regarding ventilation. 

But the problem most likely is actual water rising from the ground to external walls? This is common problem in Spain, buildings haven't got DPC  and DPM', the fix is expensive and not necessarily effective due to materials and methods used on the buildings.

Both are typical Masa problems. Internal condensation because of the solid concrete walls, even cooking in winter can cause problems. Ventilation essential, but you'll lose heat as well.

Rising damp is actually quite a problem considering the lack of rain, but there is no damp course in a Masa build. It also depends on the porosity of the concrete in the underbuild/foundations and who made and poured it. My Masa house had a basement with a small window at the front, but it always had high humidity (and a musty smell) in it even in Summer, and it was intended by Masa to be habitable.

Unfortunately that's what you get with a Masa property.

Abbey67, that would be terrible, the smell. Sewerage seeping from the pipe.. RMA44 will have to answer to that