The new regulations for changing the use of premises to housing

Converting a commercial space into a habitable home has become one of the fastest ways to expand the residential stock without building new structures. However, the change of use from commercial to residential —also referred to as property reclassification, transformation of commercial space into housing, or conversion of commercial premises— requires compliance with increasingly stringent technical regulations and navigating an administrative maze that varies by municipality.

In this guide of over 1,600 words, developed with advanced criteria, you will find a rigorous breakdown of the current state and regional legislation in 2025, the construction requirements of the Technical Building Code (CTE), and the steps to obtain the coveted first occupancy license.

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Current legal framework (2025)

A key point in 2025 is that most municipalities have tightened control over changes of use to prevent homes without minimum habitability conditions. This means that, even if the space is yours and is “well located,” it is not always feasible to convert it into housing. The new regulations and municipal interpretations focus on three aspects: real ventilation, natural lighting, and strict compliance with the CTE.

Therefore, before investing in a renovation, it is advisable to request a urban report and conduct a preliminary technical study. In many cases, this initial analysis prevents spending thousands of euros on a project that the municipality could deny.

Reference state legislation

• Land and Urban Rehabilitation Law (TRLSR 7/2015): classifies the change of use as an edificatory action that requires a planning license.
• Royal Decree 314/2006 and its update RD 732/2019: approve and modify the CTE, mandatory for all rehabilitation works with a change of use.
• Housing Law 2025: strengthens the standards of habitability and energy efficiency for the new resulting homes, with special attention to universal accessibility. DiG Abogados

Note: the Housing Law 2025 requires that any housing created by change of use must provide, at a minimum, a 25% improvement in energy rating compared to the initial state.

Autonomous and municipal competence

Each autonomous community publishes its Habitability Decree (in Madrid, Decree 111/2018; in Catalonia, Decree 141/2012, etc.). These texts establish:

1. Minimum usable area (32 m² in Madrid, 36 m² in Catalonia).
2. Clear height (≥ 2.50 m in rooms and ≥ 2.20 m in bathrooms and hallways).
3. Natural lighting coefficient (opening/area ratio ≥ 12%).

Additionally, the General Urban Planning Plan (PGOU) of each municipality may:

• Restrict conversion on certain streets (protection of the commercial fabric).
• Require one parking space per new housing unit.
• Limit the density of residential units per block. ArQuality.es

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Technical requirements for habitability

Area, distribution, and accessibility

Requirement	CTE / Decree	Minimum detail
Usable area	SU-1 (Madrid)	32 m² total; 10 m² master bedroom
Clear height	DB‑SI 3.1	2.50 m in main rooms
Accessibility	DB‑SUA 9	Adapted route to the public road

In addition to these direct costs, it is advisable to anticipate indirect expenses that many people do not calculate at the beginning of the project, such as:

• Utility connection fees (water, electricity, gas if applicable) and adaptation of installations.
• Processing of electrical bulletins and installation certificates.
• Fees for management or lawyer if there is community opposition or urban incidents.
• Extra soundproofing cost if the premises adjoin commercial activity or high traffic.

In Madrid and Barcelona, these extras can easily account for an additional 5% to 12% on the initial budget, so it is advisable to calculate realistic margins before starting.

Explanation: meeting these requirements avoids penalties and speeds up obtaining the habitation certificate.

Lighting and ventilation

1. Cross or mechanical ventilation that guarantees 0.63 renewals/hour.
2. Glazed openings equivalent to 12% of the surface area of each room.
3. Light wells: minimum section 1/3 of the height of the building to ensure zenithal lighting.

These requirements stem from DB‑HS 3 Health, whose latest revision in 2024 increased the minimum ventilation rates by 15%. reforvic.com

Thermal and acoustic insulation

• DB‑HE 1 sets ≤ 0.38 W/m²K for enclosures in zone D (Madrid, Zaragoza).
• DB‑HR requires achieving 50 dB of airborne insulation between the new dwelling and adjoining premises.

Practical keys:

• Replace carpentry with profiles with RPT and low-emissive 4/16/4 glass.
• Install sound-absorbing backings with 70 mm mineral wool.

Fire safety

The Basic Document SI imposes:

• Evacuation length ≤ 25 m to exit to a safe area.
• Resistance EI‑60 in floors that separate different ownerships.
• Installation of autonomous alarm in housing if area > 120 m².

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Step-by-step administrative procedure

1. Urban feasibility study

A licensed architect examines the PGOU and the Cadastre to confirm that the premises:

• Has compatible use with the planning.
• The density of residential use allowed is not exceeded in the block.

2. Visado technical project

The change of use project includes a report, plans, compliance with CTE, and budget. It must be visado by the College of Architects to ensure its suitability.

3. Change of use license

Requested at the Urban Planning Management. Typical documentation:

• Visado project.
• Proof of fee (≈ 7 % of the material execution budget). ARQUITASA
• Initial energy efficiency certificate.

4. Major or minor work license

If the renovation alters structure or facade → major work.
If it involves interior work without structural impact → minor work.

5. Work direction and safety coordination

The architect directs the work and the surveyor controls safety and health in accordance with RD 1627/1997.

6. Final work certificate & occupancy certificate

Once the renovation is completed, the updated building book is delivered and the property is registered as housing in the Cadastre.

7. Registry inscription

The notary issues a completion certificate; with it, the registrar modifies the use in the Property Registry, an essential requirement to apply for a mortgage or legally rent.

Change of use from commercial to residential in the Cadastre: how to update it

One of the most common questions is the change of use from commercial to residential in the Cadastre. It is important to understand that the Cadastre does not “authorize” the change of use, but it must reflect it correctly once the residence is legal.

Normally, the Cadastre is updated after registration in the Registry or after obtaining the final license. To do this, a declaration of cadastral alteration is submitted along with technical and administrative documentation.

• Cadastral reference of the original commercial property.
• Municipal license or favorable resolution of the change of use.
• Final work certificate signed by a competent technician.
• Public deed with the change of use.
• Updated plan or usable area to justify the new state of the property.

Updating the Cadastre is essential because it affects the IBI, the fiscal description of the property, and the possibility of processing a mortgage or selling with full legal certainty.

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Indicative costs (2025)

Concept	Percentage / Amount	Comment
Municipal fee for change of use	6 %‑8 % PEM	Varies according to ordinance
First occupancy license	180‑250 €	One-time payment
Technical fees	10 %‑12 % PEM	Includes drafting and direction
VAT on renovation	10 %	Primary residence < 2 years
ICIO	4 % PEM	Some municipalities apply green bonuses

Summary example: for a work of 40 000 €, taxes and fees amount to ~9 500 €, excluding materials.

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Main obstacles and how to overcome them

1. Insufficient free height
   • Solution: lower the sanitary slab or raise the roof if the volume regulations allow it.
2. Insufficient ventilation patio
   • Solution: incorporate hybrid systems with certified heat recovery.
3. Community rights

   Common mistakes when converting a premises into housing (and why they can block your license)

   1. Buying the premises without prior urban report: many investors find out too late that residential use is limited by planning.
   2. Not meeting actual ventilation or lighting: especially in interior premises or those with small patios.
   3. Not reviewing the homeowners’ association: if it affects the facade, downspouts, or common elements, the project may be halted.
   4. Underestimating acoustic insulation: it is one of the most demanded points in final inspections.
   5. Not updating the Cadastre and Registry: if not regularized correctly, it may be impossible to mortgage or sell with legal security.

   These mistakes are responsible for a large part of the delays in licenses and projects that end up being economically unfeasible.

   • The Horizontal Property Law (latest reform 25‑06‑2025) requires 3/5 favorable votes if the conversion affects common elements. BOE

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Specific regulations in large cities

Madrid

• Article 8.1.28 of the Urban Regulations: prohibits the change of use in premises with a facade less than 3 m wide.

In practice, the new regulation for changing the use of premises to housing in Madrid is being applied with particular rigor in areas where the City Council wants to preserve economic activity and local commerce. This means that in certain neighborhoods, the change of use may be denied even if it is technically feasible, especially if the premises are considered strategic for maintaining the commercial life of the street.

Another common aspect in Madrid is the requirement that the resulting housing has a logical and functional layout, avoiding “loft” type solutions without real compartmentalization. Municipal technicians increasingly value residential quality: effective ventilation, rooms with natural light, and compliance with minimum real surface areas, not just on paper.

• Requires direct ventilation to the facade of the master bedroom.

Barcelona

• PEUAT 2023 limits conversion in saturated areas of Ciutat Vella.
• Minimum usable area: 36 m²; if it is 25‑35 m², it is allowed as public protection housing.

Valencia

• Introduces from 2024 the figure of “pass-through housing” for premises that run through the building from facade to facade, as long as they meet 70% natural lighting.

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Frequently Asked Questions

• How long does the complete process take?
  Between 6 and 12 months, depending on the complexity of the project and the municipal workload.
• Can I deduct the VAT from the renovation?
  Yes, if you allocate the housing for rent for at least 5 years and register for IAE.
• Do I need a ten-year insurance?
  Only if the work affects load-bearing structure or increases built area > 10 %.

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Conclusion

The change of use from premises to housing presents itself as an attractive option for investors and individuals seeking profitability or a first residence in consolidated urban areas. However, the success of the process depends on aligning three pillars:

1. Scrupulous regulatory compliance (CTE, autonomous decrees, PGOU).
2. Realistic economic planning, taking into account rates, taxes, and fees.
3. Qualified technical advice, capable of anticipating obstacles related to height, ventilation, or community voting.

By following the legal and technical guidelines described, you will obtain a home that not only complies with the law but also maximizes its market value thanks to an efficient, healthy, and energy-optimized design. This transforms a premises into a future residential space, prepared for the habitability standards that Spain requires in 2025 and beyond.