In Spain when you want to make building works you should differenciate on MINOR and MAJOR works.
1.MINOR WORKS:
Building works don´t affect to the main parts of the building as the structure or the facade Ex: Renovate bathroom, kitchen, change partitions, painting,...
The legal conditions depends on every townhall:
In Murcia the m2 of partitions you can build is limited to 22 m2 but in Valencia, Orihuela, Yecla,Lorquí… It´s not limited.
Some townhalls requests a technician to verify and response of the works
Some Corporations typify façade works as minor, other as major works.
Abstracting: Most works we make to reform our house or commerce if it don´t affect structure or global outside aspect
2. MAJOR WORKS:
The rest of building works. Ex: Build new houses, Total renovation in buildings including facades…
There´s other important differences:
3. TIME to obtain licenses:
MINOR: Immediate or 2 or 3 weeks. In minor work if you don´t obtain your license you can have problems to obtain container for rubble and can be sanctioned.
MAJOR: 4 or 6…12 Months It dependes on the desire to work of the feared Spanish functionary 
4. COSTS AND NEEDS: (Not including working budget )
MINOR: Taxes: 4 % of Working budget.
Technician: Most of townhall don´t requires technician for this works but if it could be needed to make some visa plans or and estimate of the works. The costs depends of the project needed.
MAYOR: Taxes: 4 % of working budget
Technicians: For example a new family house: (not in edifice)
Project: Made for an Arquitect
Dirección de obra: (supervising Works): Normally made for the same arquitect
Dirección de ejecución: Other control and supervising works. Need an “Arquitecto Técnico” (as I am)
Seguridad y salud : (safe and healty in construction works) : Need an “Arquitecto Técnico”, for a project and a coordination at works, normaly the same as the previous.
Deposit: The townhall will require a deposit for damages in the street
It´s very difficult speaking about exact costs, I can analyze yours if you want. If you have some estimates for your minor or mayor work and want me to check it , I can do it in private message for free.
If the working is to open a commerce,bar,restaurant, you will need also an Activity Project for an Activity license and another tax for Activities but that will be other post…
Sorry about this boring post and my bad English… I accept corrections to improve it.
In attention to previous comment this is the aplication form to minor works in Valencia:
http://www.valencia.es/twav/impresos.nsf/vCategorias/962C27BA726672FCC125756E0049A7A7/$file/31.46-148_lic%20menores%20viviendas%20R.pdf?openElement