Why Your Renovation Must Follow the Approved Project
Published: 1 September 2026
A renovation can begin with an approved project and still run into serious problems if the work carried out on site starts to differ from the authorised plans. A recent case reported by The Scottish Sun provides a useful example. A homeowner in Sandbanks, Dorset, replaced a bungalow with a three-storey house, but changes were made during construction that did not match the approved plans. These reportedly included an extended balcony, additional side windows and an air-conditioning unit on the roof. Retrospective planning permission was later granted, but that decision was subsequently quashed by the High Court following a challenge to the planning process. The case took place in the UK and is not a precedent for Spain, but the practical lesson is widely applicable: the approved project should remain the reference point throughout construction.
When a Renovation Deviates from the Approved Project: Lessons from a Real Case
The problem did not arise because the property had been built without any initial permission. The conflict developed because parts of the finished building did not correspond with what had originally been approved.
According to the published report, some of the changes also affected neighbouring properties, particularly in relation to privacy and noise. The owner was required to apply for retrospective planning permission. That permission was initially granted by the local authority, but the decision was later quashed by the High Court following a challenge concerning the planning process.
At the time of the report, a fresh application had been submitted in an attempt to regularise the property. The article also stated that no enforcement action appeared to have been taken at that stage.
The important point for anyone planning a renovation is straightforward: having permission at the start does not automatically authorise every change made afterwards. If the scope changes, you need to establish whether the existing approval still covers the revised work or whether further technical or administrative approval is required.
What Can Go Wrong If the Work Does Not Match the Approved Project?
Fines, Work Stoppages and Possible Reinstatement
The consequences depend on the country, municipality, property, type of work and extent of the deviation. In general terms, work that does not comply with the relevant approval can lead to inspections, administrative requirements, sanctions, a work stoppage or an obligation to alter what has already been built.
If unauthorised elements cannot be regularised, they may need to be removed or rebuilt. In more serious cases, this can involve partial demolition or more extensive demolition works.
Relying on the idea that a change can simply be “legalised later” creates unnecessary risk. Retrospective authorisation is not guaranteed. The consequences can become more significant where a change affects structural elements, building volume, façades, use, accessibility, safety, installations or neighbouring properties.
Extra Costs, Delays and Insurance Issues
Correcting work after it has already been completed is usually more disruptive than reviewing a proposed change before construction continues.
Possible consequences may include:
- Revised drawings and technical documentation.
- Additional professional fees.
- Administrative procedures or fees.
- Removing and rebuilding completed work.
- Delays to the construction programme.
- Delays to utility connections or final administrative approvals where these apply.
- Potential complications involving insurance or liability towards third parties.
For homeowners and property investors, these issues can also create uncertainty when a property is later sold, let, refinanced or subjected to technical due diligence.
How to Keep Your Renovation Properly Controlled
7 Practical Recommendations
- 1. Confirm the scope and approved drawings before work starts. The owner, contractor and technical team should all be working from the same current documentation.
- 2. Confirm the correct permission or administrative procedure. Different types of work can require different forms of planning control.
- 3. Do not improvise significant changes on site. Before moving openings, altering façades, changing major installations or substantially modifying the layout, assess whether the proposed change affects the approved project.
- 4. Process project amendments where required. A significant change may require revised drawings, technical documentation or an amendment to the relevant enabling permit or authorisation (título habilitante).
- 5. Keep a clear record. Retain revised drawings, technical instructions, relevant correspondence, approvals and photographs of key construction stages.
- 6. Carry out inspections at key milestones. Check setting-out, structural work and installations before they are concealed behind walls, ceilings, floors or finishes.
- 7. Work with qualified professionals. Where the scope requires it, the contractor should coordinate with the appointed technical supervisors (dirección facultativa) and other competent professionals.
Correct Permissions and Proper Change Control
In Madrid, the administrative procedure will depend on the type and scope of work. Depending on the project, this may involve planning permission or a responsible declaration (declaración responsable), together with the technical documentation required for that particular intervention.
Madrid City Council (Ayuntamiento de Madrid) expressly provides for the modification of planning licences and responsible declarations where significant variations are introduced compared with the project originally submitted. The procedure and documentation required depend on the type of authorisation and the proposed change.
For that reason, a change should ideally be reviewed before it becomes completed construction.
In a full renovation in Madrid, a useful change-control process should record what is changing, why it is changing, who has reviewed it, whether it affects cost or programme, and whether revised technical or administrative documentation is required.
A similar principle applies when urban-planning conditions themselves change. Our guide to the Tetuán planning case explains why the planning status of a property should be checked before work begins.
A Typical Permission and Change-Control Process
Although the exact administrative requirements vary from one project to another, a well-controlled renovation can generally follow this sequence:
- 1. Define the scope. Establish the proposed layout, installations and main construction work.
- 2. Carry out the technical review. Identify the documentation, professional involvement and permissions required.
- 3. Complete the relevant administrative procedure. Submit the required documentation and obtain or activate the appropriate authorisation where applicable.
- 4. Check the setting-out before construction. Compare actual dimensions, drawings and the agreed scope before committing to irreversible work.
- 5. Inspect critical milestones. Review important construction and installation stages before they are covered.
- 6. Control changes. Document proposed variations and confirm whether revised approval or technical documentation is needed before carrying them out.
- 7. Carry out a final review. Check that the completed work corresponds with the latest approved and agreed documentation.
This approach is not only about regulatory compliance. It also helps protect the budget, construction programme and quality of the finished renovation.
Doing It Properly the First Time Protects Your Investment
A professionally managed renovation should make it possible to establish what was approved, what was actually built and how any changes were controlled.
The Sandbanks case illustrates how apparently manageable changes made during construction can later develop into a much more complicated technical, administrative and financial issue.
Good planning does not mean that a renovation can never change. Changes are common during construction. The key is to identify them early, assess their implications and document or obtain approval for them before they create a larger problem.
If you are planning a renovation in Madrid, you can request an initial, no-obligation assessment from Maceta y Cortafrío. We can review the proposed scope of the building work and help identify which aspects should be confirmed with the relevant technical professional or authority before the renovation moves forward. Where specialist technical studies or professional documentation are required, any associated scope and cost should be established separately before that work is commissioned.
Frequently Asked Questions
Can I Change the Layout During a Renovation?
Potentially, yes. Before carrying out the change, however, you should establish whether it affects structural elements, installations, the façade, the use of the property, safety requirements or the technical documentation already submitted or approved.
Does the Original Planning Permission Cover Every Change Made Later?
Not necessarily. A material variation may require revised technical documentation or an amendment to the relevant permission or responsible declaration. The correct procedure depends on the property, municipality and scope of work.
What Happens If the Finished Work Does Not Match the Approved Project?
The situation needs to be assessed individually. Retrospective authorisation may be possible in some circumstances, but it should never be assumed. If the work cannot be regularised, alterations or removal of unauthorised elements may be required.
Who Should Check That the Work Matches the Project?
Responsibilities depend on the type of project. In practice, the owner, contractor and any appointed technical professionals should work from current documentation and maintain a clear process for reviewing and approving relevant changes.
Important Disclaimer
This article is provided for general information only and does not constitute legal, planning or technical advice. Planning and building-control requirements vary between countries, municipalities, properties and types of work. A UK case should not be used to determine the legal position of a renovation in Spain. Before making decisions that affect permissions, an approved project or regulatory compliance, consult the competent authority and, where appropriate, a suitably qualified professional in the jurisdiction where the property is located.
Sources
- The Scottish Sun — case report published 5 August 2026 and updated 6 August 2026. Source consulted online.
- Madrid City Council (Ayuntamiento de Madrid) — official information on amendments to planning licences and responsible declarations.
