If looking to open up a B&B / Apartments and purchasing an older property, be aware that costs can be considerable.
For example, to get change of use (i.e. the paying public will use the property), you will have to go through an architect (Collegio Oficial de Arquitectos de Asturias), whose fee will be calculated using scales provided by the Collegio.
E.g If you wanted to restore a property of 500 sq. m of floor space and open it as a 2* Rural Hotel then expect architect fees of around 33000 Euros. This excludes other fees such as quantity surveyor, health & safety study, structural survey, electrical project and licenses.
Change of use in Asturias, also requires conformance to the latest planning regs. This can also produce unexpected costs, as many properties have beams under the minimum size which can get costly to replace, especially if it means taking the whole roof off.
This is the general approach, the one area I’m not sure if they take such a rigid view in terms of Building Regs, is if you were going to operate as a Case de Aldea.
Given labour costs account for the ‘lion’s share’ of any budget; a lot of people who are renovating old buildings, strip off the roof, remove everything inside and insert an RSJ framework which everything is built upon. This gets rid of the slow unfolding of ‘surprises’ that pushes the budget up and up.
If buying an older building, even if the property is less than 100 years, check the local town hall’s register of antiquity; as this can limit you.