Extensions, annexes, enclosed balconies and internal alterations carried out without a planning procedure rarely trouble the people living in the property. They surface when it has to be sold, financed, formally let or inherited, and that is when they stall the transaction.
First: establish what exists in fact and in law
Before choosing any route, three realities must be reconciled:
- What is built, surveyed and measured on site.
- What is described in the land registry certificate and the tax register.
- What is permitted, in the municipal file for the building.
The gap between these three readings defines the problem. Without that reconciliation, any estimate of cost or time is guesswork.
Typical situations and how they sit
- Work predating the current planning and building regime. Construction with sufficient proof of age may fall under its own regime, subject to documentary evidence — old drawings, dated aerial imagery, tax records.
- Internal alteration with no change of area or structure. Usually the simplest route, by prior notification or legalisation with an alterations design.
- Extension or annexe. Requires checking whether the construction complies with the ratios and setbacks of the municipal plan in force. If it does not, legalisation may be unviable and partial demolition becomes the only route.
- Change of use. Moving from warehouse to dwelling, or dwelling to short-term letting, brings habitability requirements the existing construction may not meet.
What the process involves in practice
- Architectural survey of the existing building.
- Review of the municipal file and the applicable local plan.
- Technical opinion on viability, identifying what can and cannot be legalised.
- Legalisation design and any required engineering disciplines.
- Submission to the municipality and follow-up to decision.
- Updating the land registry and tax register once approved.
Time, cost and risk
The timeline is driven by the municipal stage, not by preparing the design. Expect months, not weeks. Cost depends on what has to be physically corrected, not only on the design work. And one risk must be accepted at the outset: part of the construction may not be legalisable. Knowing that before selling or signing a promissory contract is far better than discovering it during the lending valuation.
If you are buying
Do not accept "it can be legalised later" without a technical opinion. Ask for the use permit and approved drawings and reconcile them against the property. A prior check costs a fraction of what a property that cannot be financed costs.
DINAMESTRIA assesses legalisation viability, submits and follows municipal procedures, and verifies compliance during purchases. Start with our Technical Consultancy unit.