Building permit: Frequently Asked Questions

ARCHITECTURE

Apr 16

Written By Francisco Javier Muñoz Fuentes

If you're thinking about building a house, renovating an apartment, or even extending your current home, there’s one step you can’t skip: applying for a building permit. Getting this approval is essential to avoid fines, ensure your project is legal, and make sure everything is done safely. In this article, we’ll explain everything you need to know about building permits:

WHAT IS A BUILDING PERMIT?

A building permit is an administrative authorization granted by the Town Hall that allows you to legally carry out construction work—whether it’s new construction, renovation, extension, or demolition. It confirms that your project complies with current urban, technical, and safety regulations.

In other words, it’s the official green light to start construction—and without it, not a single brick should be laid.

WHEN IS A BUILDING PERMIT MANDATORY?

The short answer: almost always, if the work affects the building’s structure or layout.

Building permits are generally divided into two main categories:

1. Major Building Permit

Required for:

New constructions
Complete renovations
Structural changes, or alterations to façades or roofs
Increases in built surface area
Change of use (e.g., converting a commercial unit into a residence)

2. Minor Building Permit

Applied to simpler works, such as:

Interior refurbishments that don’t affect structure or façade
Replacement of finishes or windows/doors
Maintenance or conservation tasks

Each Town Hall has its own criteria for what qualifies as major or minor work, so it’s always best to check with a professional or your local council.

WHAT HAPPENS IF I CARRY OUT WORK WITHOUT A PERMIT?

Doing work without a building permit is considered an urban planning violation, and may lead to:

Significant financial penalties
Immediate suspension of the construction
Inability to register the home or connect utilities

Also, in the event of a claim (like a fire or collapse), your insurance may not cover the damages if the work wasn’t legal. That’s why I always tell my clients: applying for a permit isn’t just a formality—it’s a legal and technical safeguard.

TELL US WHAT YOU NEED

WHAT DOCUMENTS DO I NEED TO APPLY FOR A BUILDING PERMIT?

Depending on the type of project, your Town Hall will ask for different documents. Generally, you’ll need:

Endorsed technical project, prepared by a registered architect (for major works)
Technical report (for minor works)
Estimated construction budget
Basic health and safety study
Municipal application form
Proof of payment of fees and taxes (ICIO)

Your architect can take care of preparing and submitting this paperwork, as well as tracking the application until it’s approved.

HOW LONG DOES IT TAKE TO GET A BUILDING PERMIT?

Timeframes vary depending on the Town Hall and the nature of the work. For minor works, it can take between 1 to 4 weeks. For major projects, the process can take 2 to 3 months, especially if additional reports are needed from Heritage, Environment, or other departments.

Having a complete, well-prepared application from the start helps minimize delays.

WHAT ARE THE ADVANTAGES OF GETTING A BUILDING PERMIT?

Applying for a building permit might feel tedious, but it comes with many benefits:

Avoids fines and legal issues
Allows you to take out construction insurance with peace of mind
Makes it easier to sell or rent the property in the future, as everything is properly registered
Ensures the work meets safety and quality standards

At Munoz Barcia Architects, we support our clients from day one. We don’t just design your home or renovation—we handle the entire legal and technical process so you don’t have to worry about a thing. Contact us with no obligation.

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