making changes to your property

Here's a reply from a similar question:

If you are changing the structure of the building, that is changing walls, adding living areas, building extensions etc then you will need a major works licence from the planning office at your ayuntamiento. This needs to include architect plans, dimensions of the area and so on. There will be a tax on the major works planning permission of between 2 and 6 percent of the work being carried out.

Once permission has been given, it will increase your council tax taking into account the extra living area. You would also need for your deeds to be updated showing the new layout by using the architect's final project report so that the property description can be updated at the land registry.

Failure to do this could mean delays when coming to selling the property. If this work is done without permits obtained (that is, illegally) then the process of updating deeds and so on will take some time and they could be hit with a bill for the extra IBI since having the work done. The ayuntamiento, in some cases, could also demand the work to be undone and put back to its original condition but that would be very rare.

You need to provide a deed of works with all the documentation, including building permit, to a notary who will update the records and ensure the tax on the building works (varies between 1 and 1.5%) has been paid. 

Hi, I am in Alicante City but have recent experience  re building permissions. As stated, there is permission required for minor works, and major works. It's easy enough to see which category your work fits into by doing a bit of googling. However, I have learnt that it is common practice to apply for minor works permission- which is easier to get quickly, even though the level of work may exceed that. Often if you use a builder he will make the application for you. (Note though, that it is the homeowner who is obliged to ensure the permission has been obtained, not their builder) This then covers you if you are challenged during the building process- ie over noise complaints or demolition waste etc. I struggled with the paperwork as I didnt have a builder to do it for me ,so actually engaged a friendly Spanish architect to make the applications for me. They of course have excellent first hand experience of what is required to keep the town hall happy- and you legal for any future resale. Backed up by their professional qualifications, the permission was granted immediately the application was made. Cost was in the hundreds, so for me, well worth it. 

I've just bought a place and plan to build a small utility room extension, it'll be for a washing machine, our bikes and tools, the roof will be a terrace, I'll do most of the work myself so how do I put a price on that?

You could get a couple of quotes from local builders.

Thanks for that, it seems quite obvious now, I think I'll get an architect to draw up a plan and also ask his advice about the price, apologies to Rena for jumping on the the thread but it is related and might provide some useful info.