By “vertical extension” we mean the construction of a new floor (or floors) on top of an existing building. This can apply to detached houses, two-storey homes, and apartment buildings, where additional ownership and rights issues often arise. In most cases, a Building Permit is required, and the process is submitted electronically through the e-Permits system.

What “allowed” really means in a vertical extension

When someone asks, “Am I allowed to build a vertical extension?”, they are essentially asking three questions at once. First, whether the area’s planning rules allow additional height or more square meters. Second, whether the existing building is lawful and the documentation is clear, so the permit file can move forward without obstacles. And third, whether the building can technically cope—not only with the weight of a new floor, but also with the impact such a change has on the building’s overall seismic behavior.

The legal framework for general building rules is the New Building Regulation (NOK), together with any special provisions that apply locally. This matters in practice: two properties that look similar can be subject to completely different restrictions, depending on their location and the regulations in force there.

When a vertical extension may be possible

Usually, feasibility starts with a basic question: has the permitted building capacity and height already been exhausted? In many cases—especially with older buildings or plots that were never fully utilized—there may be remaining “allowance” that could enable an additional floor. That doesn’t mean you automatically proceed. It means it’s worth carrying out a serious, structured assessment.

At the same time, you must rule out cases where special restrictions apply. In certain areas or within specific planning frameworks, there may be constraints that directly affect licensing. For example, there are situations where, due to special provisions (such as planned arcades that have not been opened), a building permit is not granted for any kind of extension. That is why the evaluation cannot be based on assumptions or a general impression. It must be grounded in the actual data of the property.

Another point that often comes up is whether an extension can follow the existing building outline. In some cases, it is stated that a vertical extension to a lawfully existing building may extend up to its existing footprint, under specific conditions and provided no special provisions prohibit it. This is an area that requires careful attention: it is not a “rule for everyone.” It is assessed based on the facts and the regulations applicable to each individual case.

What the engineer checks before any design work begins

The right starting point is not to immediately design the new floor. The right starting point is to confirm whether there is a clear path to obtaining a permit and whether the solution can stand safely.

The planning assessment is the first link in the chain. The engineer checks what is permitted for the specific plot: allowable height, allowable floor area, distance requirements, and any special local terms. This clarifies the “can we” and the “up to what limit” before time is spent on drawings that may not be licensable.

Next comes verification of the existing building. Many properties—especially older ones—have discrepancies between plans and reality or missing elements in older permit files. If these issues are not addressed early, the process can slow down or become blocked later. For this reason, a proper survey is carried out, documentation is reviewed, and a clear picture is formed of what is lawful, what is recorded, and what may require correction or regularization.

The most critical evaluation, however, is structural. A vertical extension effectively changes the building: it introduces new loads, alters mass distribution, and in many cases changes the way the structure responds during an earthquake. The structural engineer assesses the load-bearing system and foundations, examines the building’s condition (wear, defects, cracking), and determines whether the building can support the extension as it is or whether strengthening is required. In Greece, assessment of existing structures is linked to the KAN.EPE. framework (Regulation for Interventions).

This is often the point where the entire picture changes. In many cases, the right solution is not simply “build one more floor,” but “build one more floor and strengthen the structure where needed,” so the result is genuinely safe and technically justified.

What permit is required—and why it’s not a “quick” process

For a vertical extension, the process is completed through a Building Permit and includes the required studies (architectural, structural, and any other studies needed depending on the case). Submission and issuance are carried out through the e-Permits system.

If someone is looking for a “quick fix,” they may be disappointed—not because it’s impossible, but because a properly executed vertical extension must rest on two foundations: it must be legal and it must be safe. When the right steps are taken from the beginning, the project moves forward more smoothly and unpleasant surprises are avoided.

Common questions

The right first step

If you are considering a vertical extension, the best first step is a preliminary assessment: what is allowed under planning rules, what the legal status of the existing building shows, and what the first structural picture looks like. This gives you a clear answer on whether it is worth proceeding to full design work—and what the safe, realistic plan should be.

If you wish, we can review your property’s information, confirm what is permitted, and outline the steps required, so you can move forward with confidence and without unnecessary delays.

The post Vertical Extension: When It’s Allowed and What an Engineer Checks appeared first on Katsouris Engineering.

In this article, we explain in simple terms:

• when Eurocodes apply,
• when KAN.EPE. is required,
• and what all this means in practical terms for a property owner.

When Property Owners Encounter the Eurocodes

Eurocodes do not apply only to large apartment buildings or public projects. In reality, property owners encounter them much more often than they might expect.

Whenever a new building, an additional floor, or a residential extension is designed, the load-bearing structure must be studied according to the applicable Eurocodes. These standards define how loads are distributed, how a building behaves during an earthquake, and how construction materials work together.

In simple terms, Eurocodes answer the question: “How should a building be designed today in order to be safe?”

Learn more about structural design for new buildings

Why Older Buildings Require a Different Approach

Most buildings in Greece were constructed in different periods, under older regulations or with incomplete technical documentation. Many have undergone modifications, while others have been affected by earthquakes or natural material ageing.

In such cases, applying the rules used for new construction is not sufficient. An existing building has a “history” that must be assessed on its own terms.

This is precisely why KAN.EPE. exists—it focuses exclusively on the safety assessment of existing structures.

What KAN.EPE. Is and What It Examines in Practice

KAN.EPE. (Greek Code for Structural Interventions) works like a health check for a building. It does not assess how the structure should have been built, but how it behaves today and whether it can continue to be used safely.

The engineer documents the building’s geometry, examines construction materials, and evaluates its seismic performance. If weaknesses are identified, technical solutions or strengthening interventions are proposed—only where they are truly necessary.

A structural adequacy assessment is commonly required in cases such as:

• older buildings without a complete technical file,
• regularisation of unauthorised constructions,
• changes of use,
• completion of the Building Identity File.

Learn more about structural adequacy studies for existing buildings

Eurocodes and KAN.EPE.: How They Work Together in Practice

Although these are different regulatory frameworks, they often work together in real projects. For example, when an additional floor is added to an existing building, the existing structure is assessed under KAN.EPE., while the new construction is designed according to the Eurocodes.

Their correct application requires experience and a comprehensive understanding of the project. There is no single solution for every property – each case must be evaluated individually.

When Laws and Authorities Require Them

These regulations are closely linked to:

• Law 4495/2017,
• regularisation of unauthorised buildings,
• the Building Identity File,
• property transfers and changes of use.

In older properties where no technical file exists, a new survey or a structural adequacy study may be required in order to document the safety of the load-bearing structure before any procedure can be completed.

What This Means in Practice for Property Owners

For property owners, the key question is simple: Can I use or transfer my property without risk?

The answer depends on whether the structural condition has been properly assessed and the appropriate regulations have been applied. Those who start the process early avoid delays, additional costs, and unpleasant surprises.

Structural assessment is not an obstacle—it is a tool that protects both safety and property value.

Frequently Asked Questions (FAQ)

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Many homeowners assume that solar panels are “light” or that “every roof can support them,” but in reality things are not that simple. Every roof has a different age, construction method, and load-bearing capacity. A structural assessment is therefore essential to determine whether the roof can safely support the additional weight and mechanical stresses caused by the solar panels.

Why is a structural assessment necessary before installation?

This process is not a formality. It ensures that the structure will not develop problems in the future. Solar panels add permanent weight, but more importantly, they introduce extra forces from wind, snow, and concentrated mounting points. On older buildings or tiled roofs, these loads can lead to cracking, tile displacement, or even localized failures.

For these reasons, a structural assessment has become necessary both from a technical and a safety standpoint.

What exactly does the structural assessment include?

The assessment begins with an on-site inspection. The engineer examines the type of roof (concrete slab, tiled roof, metal structure), its overall condition, and whether there are any visible issues or areas that require closer investigation.

Next, the engineer calculates the loads created by the solar system, such as:

• the weight of the panels
• the weight of the mounting structure
• wind loads (particularly important for tiled roofs)
• snow loads, where applicable

These calculations follow European standards such as EC1, EC2, EC6 and EC8 to ensure full technical documentation and compliance.

The final deliverable is the Structural Adequacy Report, an official document that includes the analysis, conclusions, and—if necessary—recommendations for small or more extensive reinforcements. With this report, the installer can proceed safely.

Is a structural check always required?

In most cases, yes. However, there are specific situations where the assessment is not just advisable — it is mandatory:

Tiled roofs

Tiled roofs are more vulnerable, especially to strong winds, and require proper mounting to avoid future problems.

Older buildings (30–40+ years old)

These buildings may have hidden weaknesses or wear not visible to the naked eye.

Lack of original plans or structural study

Very common in homes built before 1985.

Large system capacity

More panels mean higher loads.

When required by the installer or the grid operator

In many cases, the assessment is now a prerequisite.

What can happen without a structural assessment?

Solar panels are designed to operate for decades. This means the roof must remain structurally stable for decades as well.

Without an assessment, issues may arise such as:

• cracks in beams or slabs
• displacement of roof tiles
• loosening of mounting bases
• localized failures during strong winds
• insurance complications in case of damage

A small issue left unresolved at the beginning can become significantly more expensive to fix later.

What if the roof does not “pass” the assessment?

This does not automatically mean you cannot install solar panels. In most cases, required reinforcements are simple and may include:

• adding metal supports to strengthen a tiled roof
• strengthening a concrete slab with modern materials such as carbon fibers (CFRP)
• changing or improving the mounting system
• placing the panels in a different, more suitable area of the roof

The goal is always safety and long-term durability of the installation.

Cost and completion time

A structural assessment is not a lengthy process. It typically takes 2–4 days, and the cost ranges between €150–350, depending on the type of roof and the complexity of the building.

This cost includes the site inspection, calculations, photographic documentation, and the final report.

Why choose Katsouris Engineering

Our team has extensive experience in the structural analysis of all roof types and has completed numerous assessments for solar installations in both residential and commercial buildings. With every project we ensure:

• technically accurate and safe results
• close cooperation with your installer
• fast turnaround time
• clear, practical recommendations without exaggerations

Our goal is to guarantee a rooftop solar installation that operates safely and reliably for many years.

Planning to install rooftop solar panels?

We can perform the full structural assessment and guide you through every step of the process.

The post Solar Panels on Roofs: Is a Structural Assessment Required? appeared first on Katsouris Engineering.

Most owners of older houses eventually ask themselves: “Is an energy upgrade worth it?” The answer is almost always yes – and not only because subsidies are available. An energy-efficient home means lower bills, better comfort, and higher property value.

In recent years, programs such as “Exoikonomo 2025” and “Exoikonomo – Renovate for Young People” have helped thousands of homeowners significantly reduce the cost of energy improvements. Meanwhile, new initiatives expected for 2026 will further support the energy upgrade of older residential buildings.

Here’s what an energy upgrade includes and how you can benefit from available incentives.

What Does “Energy Upgrade” Mean?

An energy upgrade is a set of interventions that make a home “smarter” and more efficient in its operation. The goal is to reduce heat loss in winter and overheating in summer, so the building maintains stable comfort with lower energy consumption.

The most common interventions include:

• Thermal insulation of walls and roof

  Reduces heat loss by up to 40% and stabilizes indoor temperature.

• Replacement of old windows with energy-efficient frames

  
  Minimizes drafts, condensation, and improves sound insulation.

• Upgrade of heating/cooling systems

  
  Heat pumps, condensing boilers and inverter air-conditioning operate more efficiently with less energy.

• Installation of photovoltaic panels

  
  Allows you to generate your own electricity and drastically reduce operating costs.

• Smart thermostats & LED lighting

  
  Small interventions with immediate savings on consumption.

Once these improvements are completed, the home moves up in Energy Performance Certificate (EPC) category — a major factor that increases its market value.

Why Energy Upgrades Are Worth Considering

An energy upgrade isn’t just a technical project that ends when the work is completed. It’s a decision that pays off every single month. With proper insulation, efficient windows and modern heating systems, the home consumes less energy, which means noticeably lower bills.

At the same time, indoor comfort becomes more stable, while the property’s resale value increases — a trend that keeps strengthening in the real estate market. On top of that, you reduce the home’s environmental footprint, which many owners now consider essential.

And the best part: there are often subsidy programs that can cover a significant portion of the cost.

“Exoikonomo” Today — What Applies and What to Expect in 2026

In recent years, several cycles of the “Exoikonomo” program have been implemented, aiming to support the energy upgrade of residential buildings. The most recent cycle, Exoikonomo 2025, closed its application period on 13 April 2025 and is now in the implementation phase.

Another program, Exoikonomo – Renovate for Young People, is still active, with a completion deadline of 30 April 2026, combining energy improvements with renovation works for young homeowners.

For 2026, a new round of energy-upgrade programs is expected. However, as of today, no official guide, subsidy percentages, or application deadlines have been confirmed.

How Much Does an Energy Upgrade Cost?

The cost varies depending on the size of the house, the age of the building, and the interventions needed. Indicative price ranges:

• Wall insulation: 40–70 €/m²

• Roof insulation: 35–60 €/m²
• Window replacement: 350–900 € per opening
• Heat pump: 4,000–12,000 €
• Condensing gas boiler: 2,000–4,500 €
• Photovoltaic system 3–6 kW: 4,000–9,000 €
• Solar water heater: 900–1,800 €

Although these amounts may seem high, the real cost is significantly lower when combined with subsidies. Many households ultimately cover 50% to 90% of the total budget. Combined with the reduction in energy bills, the investment often pays back in just a few years.

Which Intervention Offers the Highest Return?

All interventions contribute to energy efficiency — but not equally. Based on experience with older homes, the ranking is:

1. Exterior insulation

The most effective measure. Reduces heat losses in winter and heat gains in summer. Rating (5/5): ⭐⭐⭐⭐⭐

2. Window replacement

Provides major thermal improvement and better comfort, especially in homes with single glazing. Rating (4/5): ⭐⭐⭐⭐

3. Heat pump

Particularly cost-effective in homes with long operating hours. Reduces heating costs by up to 50%. Rating (4/5): ⭐⭐⭐⭐

4. Solar water heater

Low installation cost and immediate results. Rating (5/5): ⭐⭐⭐⭐⭐

5. Photovoltaics

Ideal for homes with high electricity consumption and direct impact on energy dependency. Rating (3/5): ⭐⭐⭐

For homes aged 20–40 years, the best cost-to-benefit combination is usually:
insulation + windows + solar water heater.
With subsidy support, this package is often the most affordable and balanced solution.

Energy Upgrade vs. Regular Renovation — What’s the Difference?

Many owners confuse general renovation with energy upgrading. But the two concepts have different goals and outcomes.

What is a “regular renovation”?

A typical renovation involves flooring, bathroom/kitchen upgrades, painting or aesthetic improvements. It enhances the look and functionality of the space but doesn’t necessarily reduce energy consumption.

What is an energy upgrade?

It focuses on systems, materials and techniques that reduce operating costs and improve thermal comfort. It is an investment that pays off through lower bills, higher property value, and better quality of living.

Which one should you choose?

For most homeowners, the ideal approach is a combination:
start with the energy upgrade (which has technical benefits and long-term savings), then proceed with the aesthetic renovation.
This avoids repeated work and results in a modern, comfortable and cost-efficient home.

The post How to Improve the Energy Performance of an Older Home appeared first on Katsouris Engineering.

If you own a tourist accommodation, educational facility, hospital, fuel station, or any building open to the public, obtaining the certificate is now mandatory.
For all other properties, the Building Identity Certificate is required for every sale, donation, inheritance, or legalization of unauthorized constructions.

In the following guide, you will learn who is required to obtain it, which documents are needed, and how to complete the process properly and without delays.

What Is the Building Identity Certificate

The Building Identity Certificate is the digital record of each property, confirming its legal status. Through the official TEE (Technical Chamber of Greece) platform (web.tee.gr):

• Building permit and architectural drawings
• Energy Performance Certificate (EPC)
• Declarations of building legalization
• Structural adequacy study or technical report
• Floor-area distribution tables and other legal documentation

The process is carried out exclusively by a licensed engineer, who submits the data and issues the Certificate of Building Completeness.

Who Is Obliged to Obtain It

Since February 1, 2021, the Building Identity Certificate has been mandatory for all private and public buildings (Ministry of Environment and Energy). However, the following categories must obtain it by January 31, 2026:

• Tourist accommodations over 300 m²
• Schools and childcare facilities
• Hospitals and healthcare centers
• Public-assembly buildings (theaters, cinemas, gyms, etc.)
• Fuel stations, car washes, and repair workshops
• Public buildings and municipal facilities

For all other buildings (residences, apartments, offices, etc.), the certificate is required whenever

• there is a sale, donation
• legalization of irregularities
• issuance of a new building permit

Deadline and Processing Time

The deadline for special building categories is January 31, 2026, as stated by the Ministry of Environment and Energy.

The time required depends on the completeness of each file. If all documents are available, the certificate can be issued within a few days. If new surveys or records from local authorities are needed, it may take a few weeks.

View the official Ministerial Decision on the Building Identity Certificate (Government Gazette B’ 334/29.01.2021)

Fines for Delay or Non-Issuance

Failure to issue the Building Identity Certificate on time results in penalties imposed by the Special Secretariat for Environmental Inspection:

• Minimum fine: €200
• Maximum fine: Up to 10 % of the property’s objective value

The fines remain valid until the certificate is properly issued.

Documents Required by the Engineer

To proceed, your engineer will need:

1. The original building permit with all revisions
2. Updated architectural drawings and plans
3. The Energy Performance Certificate (EPC)
4. Structural adequacy study or technical report (if required)
5. Legalization declarations for any unauthorized works
6. Ownership allocation tables (for multi-unit buildings)

If some documents are missing, the engineer can issue a certificate of loss and create new digital drawings.

Why You Should Act Now

The Building Identity Certificate is more than an obligation – it is the official assurance that your property is fully legal, safe, and ready for any transaction.

Completing the process in time means you:

• avoid future fines and delays,
• are always prepared for property transfer or renovation,
• and strengthen the value and credibility of your property.

At Katsouris Engineering, we handle the entire process for you – quickly, accurately, and transparently.

Our team takes care of:

• Legal and technical compliance checks
• Collection and digital upload of all documents
• Structural adequacy inspection (if required)
• Submission to the TEE platform and issuance of the final completeness certificate

This ensures your property is fully compliant and ready for any use or transaction.

📧 Contact us for a free file pre-check and an indicative offer.

Frequently Asked Questions

The post Building Identity Certificate 2026 – Who Risks Fines appeared first on Katsouris Engineering.

What is a Demolition Permit

A demolition permit is the official administrative act that allows the removal of an existing building.
It is required:

• for the complete demolition of a building,
• for partial demolition (e.g., a floor or roof),
• or for preparatory works before new construction.

The process ensures that demolition is carried out legally and safely, without endangering neighboring buildings or passers-by.

Required Documents for a Demolition Permit

To issue a demolition permit, the following are required:

• Property titles and registration certificate
• Cadastral map extract
• Certificate of plot suitability and buildability
• Topographic survey based on the Greek Grid (EGSA ’87)
• Assignment and undertaking declarations for study/supervision
• Demolition plan (describing the method, machinery, and safety measures)
• Approval from DEDDIE/ΕYDAP (if there are utility connections)
• Approval or consent from competent authorities (e.g., Archaeology, Forestry, Ministry of Culture) where applicable

💡 In cases of fire-damaged or earthquake-damaged buildings, the demolition permit is issued through a special compensation procedure by the Ministry of Infrastructure.

Duration of the Process

The issuance of a demolition permit usually takes 1–2 weeks, depending on the completeness of the documentation.
Work can begin 20 days after the permit’s publication online, as stipulated by Law 4495/2017.

What is a Building Permit

A building permit (also called construction permit) is the next stage: it grants the owner the right to build a new structure.
It includes the approval of all technical studies and ensures compliance with current urban planning and energy regulations.

Steps for Issuing a Building Permit

1. Preliminary study and topographic verification
2. Preparation of architectural, structural, and electromechanical studies
3. Approval of building terms by the Urban Planning Authority (ΥΔΟΜ)
4. Submission of the application through the e-Permits system
5. Payment of professional fees and contributions (TEE, EFKA, IKA, engineer taxes)
6. Issuance of the electronic building permit
7. Commencement of construction with appointed supervising engineers

Required Studies

For a new building permit, the following studies are required:

• Architectural study
• Structural (static) study – and static adequacy of existing structures where applicable
• Electromechanical installations study
• Energy performance study (KENAK)
• Fire safety study (where required)
• Thermal insulation, drainage, water supply, and lighting studies

When Both Permits Are Required

• When an old or unsafe building is replaced with a new one
• In fire-damaged or earthquake-damaged properties requiring reconstruction
• For large-scale renovations that include full demolition
• When the use or structural requirements of a plot change

Cost of Demolition and Construction Permits

The total cost depends on:

• The area and location of the property
• The number and complexity of required studies
• Engineers’ professional fees
• Public contributions and insurance funds (TEE, EFKA, etc.)
• Whether a simple or reinforced foundation is required

Indicative range:

• Demolition permit: from €300–800 (for small houses)
• Building permit: from €1,500–3,500, depending on project scope

(Exact costs vary based on project type, size, and study requirements.)

Which Engineers Are Involved

The process requires the collaboration of a civil engineer, architect, and often an electrical engineer.
Katsouris Engineering manages the entire procedure end-to-end, including:

• Surveying the existing structure (3D Laser Scanning)
• Preparing all studies
• Submitting and managing the e-Permits file
• Supervising construction on-site

Example in Practice

In the reconstruction of a fire-damaged residence in Mati, the Katsouris Engineering team undertook:

• Demolition of the damaged shell
• Structural design of the new load-bearing system
• Issuance of the building permit
• Full supervision until completion
  The project was delivered with modern energy efficiency and seismic protection standards.

Frequently Asked Questions

The demolition and construction permit forms the foundation for any reconstruction or new building project.
Proper preparation and guidance by an experienced engineering team save time, money, and prevent bureaucratic delays.

📞 We undertake complete permit, design, and supervision procedures for private and professional projects throughout Greece.

The post Demolition & Construction Permit: Procedure and Required Documents appeared first on Katsouris Engineering.

The legalization of unauthorized buildings is perhaps the most critical step in ensuring the legal validity of a property. Legalization (or “regularization”) allows owners to secure the ability to sell, mortgage, or otherwise utilize their property safely, without legal complications.

What Law 4495/17 Provides and Who Is Affected

The law classifies unauthorized constructions into five categories, depending on the severity of the violation and the time of construction.
Until March 2026, Categories 1 to 4 can be included in the legalization process, which covers:

• Buildings constructed before 1983 that deviate from their building permit.
• Minor or medium violations, such as enclosed semi-open spaces or excess building area under 40%.
• Constructions with a valid permit but with alterations or small additions.

Category 5, which includes major violations or constructions without a permit after 2011, cannot be legalized. Any attempt to include such constructions is automatically rejected by the TEE (Technical Chamber of Greece) system.

The March 31, 2026 Deadline

This date serves as the final opportunity for hundreds of thousands of property owners. After the deadline, no new applications can be submitted, and any unregulated constructions will remain illegal — with serious consequences:

• No possibility of property transfer or establishment of ownership rights.
• Loss of property value, since the building cannot obtain a Building ID.
• Potential fines or even demolition orders, depending on future inspections.

Experience from previous years shows that property owners usually take action at the last moment, leading to congestion for engineers and planning authorities. Early preparation is critical to avoid delays. In properties with interventions to the load-bearing structure, this preparation also includes a structural study for new construction or additions before the completion of the regularisation process.

How Property Transfers Are Affected

Since 2021, no property transfer can take place without a valid Building ID — a digital record containing all legality documents, floor plans, permits, and any legalization declarations.

If an irregularity has not been legalized, the Building ID cannot be issued, and therefore, the property cannot be sold or transferred.
Even minor deviations, such as the relocation of a balcony or the closure of a storage area, can block a transaction or inheritance transfer.

Resolving these issues requires a qualified civil engineer experienced in legalization procedures, who will carry out a site inspection, permit file review, fine calculation, and submission through the TEE platform.

➡️ See our dedicated page on Regularization of Unauthorized Constructions
➡️ Related service: Building ID

Practical Guide: Steps Property Owners Should Follow

1. Legality check of the property by a licensed civil engineer.
2. Comparison between the approved building permit plans and the current condition.
3. Classification of the irregularity (Category 1–4) and fine calculation.
4. Submission of the legalization declaration through the TEE platform.
5. Payment of the application fee and fine (in full or by installments).
6. Final approval and update of the Building ID.

In older properties where no official building file is available, a new topographic survey or a structural adequacy assessment of the existing building may be required in order to document the safety of the load-bearing structure.

Will There Be Another Extension?

Although the possibility of an extension is often discussed, no official statement has been made.
The Ministry of Environment aims to ensure digital tracking of all declarations through the Digital Land Bank and the Building ID system, indicating a shift toward completion and transparency, rather than ongoing extensions.

Therefore, the safest approach is to start the process early to avoid last-minute congestion as the deadline approaches.

Impact on the Real Estate Market and Investors

The end of the legalization period will have a direct impact on the real estate market. Many properties with minor irregularities (such as closed verandas or attic conversions) will remain “frozen”, unable to be sold or mortgaged.

This will cause temporary stagnation in available legal properties, affecting sellers, buyers, and brokers alike.

Owners who proceed with legalization on time will gain a significant advantage — both legally and financially — as a legalized property can be immediately sold or utilized.

The Role of the Engineer

The regularisation process is far more than a simple declaration. It requires technical expertise and a thorough understanding of planning and building regulations.
The engineer is responsible for certifying legality, assessing the extent of deviations, and proposing potential improvements, structural strengthening measures, and technical solutions where required.

At Katsouris Engineering, we provide comprehensive services for the legalization of unauthorized constructions, building permit issuance, and Building ID preparation.
Contact us to review your case and ensure your property’s compliance well before the 2026 deadline.

ℹ️ Frequently Asked Questions (FAQ)

The post Illegal Constructions 2026: What Changes in Legalization and How It Affects Property Transfers appeared first on Katsouris Engineering.

What the House Construction Process Includes

Building a house is not a simple contracting job — it’s a complete project that goes through successive stages, each crucial to the success of the next.

1. Preparation & Permits

Before any work begins, a complete set of studies and a building permit are required. This includes:

• Architectural design with floor plans, facades, and site plan.
• Structural study ensuring the safety of the load-bearing structure.
• M/E studies (electrical, plumbing, heating, cooling, ventilation).
• Building permit approval from the local Urban Planning Department.

Proper design and supervision by experienced engineers ensure there will be no delays, budget overruns, or legal obstacles.

2. Construction & Supervision

The construction phase is divided into stages:

• Earthworks and foundation
• Structural frame (reinforced concrete or steel)
• Masonry, roof, plastering
• Electromechanical installations
• Doors, windows, floors, wall finishes
• Final works and landscaping

Supervision by a civil engineer is essential at every step to ensure compliance with specifications, structural safety, and energy performance.

3. Delivery & Certifications

Before delivery, final quality checks are carried out, installations are inspected, and an Energy Performance Certificate (EPC) is issued.
The project is considered complete only when it is delivered in full, with all official documents and construction warranties.

Factors Affecting the Cost of House Construction

The cost of building a house depends on many factors — not only on the size of the residence:

• Type of construction: reinforced concrete, steel, or hybrid.
• Energy efficiency: insulation, windows, photovoltaic systems.
• Material quality: from plastering to floors and joinery.
• Topography: if retaining walls, excavation, or special foundations are required.
• Building coefficients and planning restrictions.

Indicatively, in Greece, costs range between €1,200 and €1,800 per m², depending on materials, complexity, and level of finishes. A detailed cost analysis should always follow the completion of the design phase.

How to Choose the Right Construction Company

Choosing the right team is critical. An experienced and certified construction company guarantees transparency, safety, and consistency.
Here are the main criteria:

1. Research and Verify Experience

• Project portfolio: ask to see previous works and learn about their technical complexity.
• Client reviews: check ratings on Google or Facebook.
• Speak with past clients: their experiences are the most reliable source of insight.

2. Examine the Offer in Detail

• Request a detailed quotation covering all stages, with no hidden costs.
• Don’t base your choice solely on price — evaluate the quality-to-cost ratio.
• Compare material specifications and proposed timelines.

3. Legal and Technical Checks

• The company must have valid licenses and technical competence.
• It should comply with all safety and quality standards (ISO, CE).
• Verify that it provides insurance coverage for the project and staff, protecting you from liability in case of accidents.

4. Collaboration and Communication

• Discuss the timeline from the start and request written commitments.
• A reputable company provides construction warranties and monitors the project even after delivery.
• Transparent communication — with updates, reports, and photo documentation — is a key sign of reliability.

Energy Efficiency & Sustainability in Modern Homes

Today, energy efficiency is not a luxury but a necessity. New homes must comply with Greek energy regulations (KENAK) and integrate modern technologies such as:

• Thermal insulation (ETICS) and high-performance windows
• Heat pump systems for heating and cooling
• Photovoltaic panels (PV-ready)
• Natural lighting and shading
• Eco-friendly certified materials

Proper design by a civil engineer and energy inspector leads to lower consumption and increased property value.

Frequently Asked Questions About House Construction

Building a house is a journey that requires organization, transparency, and the right partners.
With professional design, consistent supervision, and respect for timelines, the result can be a modern, energy-efficient, and durable home — designed for decades of safety and comfort.

If you’re planning to start your own residence, Katsouris Engineering undertakes complete projects — design, permitting, and construction — from the initial concept to the final delivery.

The post House Construction: A Complete Guide for Homeowners Starting a New Residence appeared first on Katsouris Engineering.

When is a building permit required for a renovation?

Minor interventions such as painting walls or replacing interior doors do not require a permit. However, when the renovation includes layout modifications or structural changes, a building permit becomes necessary. Examples include demolishing or moving walls, creating new openings, or changing the use of a space. In these cases, the permit guarantees that the works are carried out in compliance with building regulations and safety standards.

Case example: Imagine a 90 m² apartment where the owner wants to remove a non-load-bearing partition wall and redesign the kitchen layout without altering plumbing. This may not require a full building permit. But if the wall were load-bearing, or if a larger opening were to be created, then a permit would be mandatory.

The crucial question to ask is: “Am I affecting the structural elements or changing the loads, volumes, or use?” If yes, then a permit is required.

Types of permits for renovations

For limited works—such as external painting using scaffolding, installing insulation, or small internal rearrangements—a Small-Scale Building Permit is sufficient. For more extensive interventions, such as alterations to structural elements or building extensions, a Category 2 or Category 3 Building Permit is required. The correct classification is vital since it determines the studies to be submitted, the supporting documents, and the time needed for final approval.

For example, building a 15 m² extension in the backyard is a structural intervention and requires a Category permit, not just a small-scale one.

The process of issuing a renovation permit

The process starts with a survey of the existing building, ensuring a complete record before design work begins. Next come the required studies: architectural, structural, topographical, energy, and in some cases mechanical studies. All documents are submitted electronically via the e-Permits (e-Άδειες) system of the Technical Chamber of Greece, allowing digital monitoring of the process until final approval. The time needed varies depending on the complexity of the project—from a few weeks for simple cases to several months for major renovations. Ideally, the process may take 45–60 days if the file is complete.

Cost and completion time

The cost depends on the size of the property, the permit category, and the required studies. For simple small-scale works, the cost remains limited. For full renovations that require structural and other studies, the amount rises significantly since engineering fees, government fees, and potential approvals from other authorities are included. A proper budget and accurate cost estimate from the beginning are the keys to avoiding overspending and delays.

Common mistakes to avoid

One of the most frequent mistakes is starting construction without a permit, hoping that inspections will not occur. This often leads to project suspension and heavy fines. Another common problem is poor communication with the engineer, resulting in delays in gathering necessary documents. Many homeowners also underestimate the time required for permit approval and schedule contractors too early, creating conflicts and extra expenses.

In summary, common mistakes and tips to avoid them include:

• Always start works only after the permit has been issued.
• Do not underestimate the time needed for file corrections—missing documents can delay the entire process for weeks.
• Request detailed quotes that separate the costs of studies, materials, works, and supervision.
• Work with an engineer experienced in renovation permits, who knows the requirements of local urban planning authorities.
• Be cautious with online “price lists” that may not include repairs, unforeseen issues, or supervision.

A home renovation can be a smooth and successful project, provided that legal requirements are met. The building permit is not a bureaucratic burden but the foundation for a safe, legal, and high-quality result. With the guidance of an experienced civil engineer, the homeowner can ensure that the project will be completed without risks or unexpected setbacks.

The post Home Renovation & Building Permit: What Every Homeowner Should Know appeared first on Katsouris Engineering.

The question “what does the small-scale building permit include” is very common. The answer is that it covers a wide range of repairs, improvements, and minor constructions, as long as they do not affect the structural integrity or change the use of the building.

Which works require a small-scale building permit

The works with a small-scale building permit are clearly defined by Greek law and mainly include low-risk, minor interventions. Typical examples are:

• Demolition of small or unsafe constructions such as fences or lightweight sheds.
• Construction, replacement, or repair of plot fences.
• Installation of scaffolding for exterior painting or façade repairs.
• Replacement of railings, windows, or external wall finishes.
• Roof or wall insulation for energy efficiency improvements.
• Trial trenches and geotechnical investigations.
• Connection to public utility networks (water, sewage, electricity).
• Minor repairs in roofs, pavements, or external spaces.

Every case is assessed by the supervising engineer, who confirms whether the work falls under the small-scale permit or requires a full building permit.

Small-scale building permit vs full building permit

Many owners wonder about the difference between a small-scale building permit and a standard building permit. The key points are:

• The small-scale permit applies to minor or medium-level works that do not alter the structure or use of the building.
  
• The full building permit is required for new constructions, major interventions, change of use, or significant structural reinforcements.

Correct categorization is crucial. Carrying out works under the wrong type of permit may result in fines and legal complications.

Required documents for a small-scale building permit

The documents for a small-scale building permit are fewer compared to a full building permit, but they must be accurate and complete. They usually include:

• Ownership documents (titles, cadastral extracts).
• Engineer’s declaration confirming the property’s legality.
• Architectural drawings or technical reports depending on the work.
• Energy Performance Certificate (EPC) when works involve insulation.
• Applicable state fees and taxes.

The process is carried out electronically through the Technical Chamber of Greece (TEE) platform and always requires submission by a licensed engineer.

Duration of validity

The duration of a small-scale building permit is usually 12 months from the date of issue. If the works are not completed within this period, an extension may be requested. Otherwise, a new permit must be issued.

Timely completion helps avoid unnecessary bureaucracy and additional costs.

Cost of a small-scale building permit

The cost of a small-scale building permit varies depending on:

• The type and complexity of the works.
• Whether plans or studies are required.
• Applicable state fees and taxes.
• The engineer’s fee for preparing and supervising the process.

Overall, the small-scale permit is much more affordable than a full building permit, as it covers only smaller-scale works.

Legalization of works under a small-scale permit

Sometimes, owners proceed with minor works without issuing the required permit. In such cases, legalizing works under a small-scale building permit is possible if the type of work is legally eligible. If detected during an inspection, fines are imposed, and legalization is usually required afterwards—often with higher costs.

It is always more advantageous to issue the permit in advance to ensure legality and avoid penalties.

Minor constructions without a permit: when is it allowed?

There are certain cases where minor constructions without a permit are allowed, typically for very small-scale repairs, such as:

• Interior painting.
• Small repairs to existing windows or doors.
• Replacement of plumbing or electrical installations without layout changes.

However, for works like external wall painting with scaffolding, façade insulation, or roof interventions, at least a small-scale permit is mandatory.

Connection with the Building Identity (ΗΤΚ)

Every new small-scale permit must be linked to the Electronic Building Identity. This ensures that the works are digitally recorded and the property remains legally compliant, avoiding future issues with transfers, audits, or additional permits.

Frequently Asked Questions

Need a small-scale building permit?

The small-scale building permit is an essential legal tool for carrying out minor construction works, repairs, and improvements. It is easier, faster, and more cost-effective compared to a full building permit, but still ensures that all works are carried out legally. The guidance of an experienced engineer is crucial to avoid mistakes, delays, or fines.

At Katsouris Engineering, with years of experience in studies, permits, and construction supervision, we manage the entire process: from document preparation and submission to completion and inspection of the works. With precision and responsibility, we guarantee smooth progress and full compliance for every project.

Contact our team today to discuss your project and guide you step by step through the process.

The post What Does the Small-Scale Building Permit Include: Works, Documents, Duration & Cost appeared first on Katsouris Engineering.

1) Incomplete or incorrect Electronic Building Identity

The Electronic Building Identity for conveyancing is the core of the technical file. If required drawings, declarations, or certificates are missing—or if the actual condition of the property doesn’t match the plans—the notary cannot proceed. Common gaps include missing permit revisions, outdated drawings, or legalization documents that were never uploaded. Even minor discrepancies (a moved interior door, a storage room being used as living space) create doubts and trigger a restart of checks. The solution is a full pre-audit of the HTK by a qualified engineer, with a written list of missing items and corrections before you book the notary.

2) Square-meter mismatches across E9, Municipality/DEDDIE, Cadastre, and HTK

If the reported area differs between your E9 tax form, the Municipality/HEDNO (DEDDIE power utility records), the Hellenic Cadastre (Ktimatologio), and the HTK, the TAP municipal tax clearance will be delayed and the transfer will freeze. This is especially common in older apartments with lofts, enclosed balconies, or confusion between net and gross area. Each agency will ask for corrections in sequence, so doing them out of order wastes time. The right order is: on-site measurement and plan update → harmonize square meters → update E9 and Municipality/HEDNO → reflect the final numbers in the HTK. When every registry shows the same figure, the file moves smoothly.

3) Unlegalized alterations

Seemingly small alterations—enclosing a semi-open balcony, changing internal partitions, adding a lightweight storage—are a red flag for conveyancing if they were never legalized. Without a proper unauthorized construction regularization and the engineer’s declaration, the notary will halt the process. Legalization usually involves an inspection, measured drawings, category assessment, and fee calculations. The earlier you start, the faster it finishes; leaving it to the end almost guarantees a postponement. Ask for a technical inspection first, so you’ll know if simple legalization is enough or if a structural adequacy study is needed because the load-bearing structure was affected.

4) Engineer’s Declaration and affidavits with typos or wrong IDs

The Engineer’s Declaration for the deed must align perfectly with the title deeds, the KAEK (Cadastre property ID), owner details, and the exact description of the unit. Typos in names, VAT numbers (AFM), dates, or floor/unit identifiers lead to rejection. If floor numbers or unit labels on the drawings differ from the deed, the notary will request clarifications or corrections. Before issuing the declaration, the engineer should cross-check: title deed & registration, cadastre sheet, HTK contents, and—where applicable—the topographic plan. Meticulous data consistency here typically saves at least a week.

5) Outdated or incorrect topographic plan (critical for plots and land)

For land (plots/agricultural parcels), you need a georeferenced topographic plan in EGSA ’87. Old drawings without coordinates, blurry boundaries, or plans that don’t match the cadastre cause dead ends. If neighbors dispute boundaries or there are overlaps, you’ll need an updated topographic and a short technical report before you set a deed date. In cases of new or amended horizontal/vertical ownership, an accurate, current plan speeds up approvals. Early assignment to a surveyor prevents queues at public services and repeated corrections.

6) Cadastre (Ktimatologio) issues: wrong KAEK, encumbrances, missing registrations

Your Cadastre data must reflect the real, current situation. If the KAEK is wrong, if an old pre-notation of mortgage still shows, or if a deed was never properly registered, the notary will not move forward. Run a pre-check of the cadastre sheet and obtain encumbrance certificates early, so you can start any required releases or corrections at once. Even small clerical errors (old spelling of a surname) can take time to amend. A tidy cadastre file gives the notary confidence and avoids adjournments.

7) Problems in the horizontal/vertical ownership deed: shares, auxiliary spaces, parking spots

A frequent blocker is a mismatch between the ownership deed and reality: a storage room used as living space, a basement merged with the apartment, or a parking spot that doesn’t match the plan. These surface during a proper site survey and raise legal concerns. The remedy is a deed amendment (where applicable) before the notary receives the file. With modern methods like 3D laser scanning, documentation is accurate and expedites approvals. Addressing this early turns a potential legal knot into a routine correction.

8) Energy Performance Certificate expired or with wrong data

The Energy Performance Certificate for sale must be valid and reflect the correct area, usage, and the actual number/state of HVAC systems. Many EPCs were issued years ago with rough measurements or have since expired. If the notary spots discrepancies, re-issuance will be required, delaying the deed. A quick on-site check updates the figures, and you’ll often receive energy-upgrade tips that add appeal to the property. Getting the EPC right removes a common last-minute obstacle.

9) TAP and municipal fees: delays caused by area inconsistencies

The TAP certificate (municipal real-estate levy clearance) requires your square meters to match across the Municipality and HEDNO records. If the power utility shows different square meters than your E9 or municipal registry, the Municipality will ask for corrections and re-calculation of fees. This can take several days, especially in busy periods. Prepare in order: measure, update square meters with the Municipality, then apply for TAP with a complete pack of documents. The cleaner the file, the faster the certificate.

10) Building rules & shared-costs (condominium) issues that surface late

A no-arrears statement for shared costs isn’t always mandatory, but buyers and notaries often ask for it. Unsettled dues or disputes with the building’s Regulations create friction and delay. Ask the manager for a recent no-debt confirmation and keep a copy of the Regulations handy. In multi-owner buildings, transparency about common expenses builds trust and keeps the deal on track. It’s a small paper that prevents big headaches.

11) Out-of-plan properties: buildability, restrictions, and special zones

For out-of-city-plan properties, you need clear documentation of buildability and checks for forest, archaeology, or coastline restrictions. Delays here come from missing certificates or an insufficient topographic plan. The correct sequence is obtain the necessary public-authority confirmations first, then book the deed. If there are grey areas, request a technical opinion so both parties understand the true development potential. Upfront clarity prevents last-minute re-negotiations.

12) Missing building-permit files and revisions

Many older properties lack plan copies, revisions, or stamped drawings. Without them, the HTK cannot be completed and the engineer’s declaration is risky. There are still options: reconstruct the permit file from the authority, where possible, or proceed with a new measured survey supported by a clear technical report. Start this search early; archives and appointments take time. Good organization from day one eliminates the “we’re missing a drawing” surprise two days before signing.

10-day preparation checklist for a “clean” deed

Begin with a technical site inspection and photos to identify any unlegalized changes or inconsistencies. Commission a measured survey (use 3D laser scanning where appropriate) so all plans, the E9, the Municipality/HEDNO records, and the Cadastre can be harmonized. For land, order a timely EGSA ’87 topographic plan and collect any forest/archaeology/coastline confirmations needed. Complete legalizations and issue a valid EPC with updated data. Finally, complete the HTK package and deliver a full, unified file to the notary 3–5 days before the appointment so minor edits don’t force a postponement.

FAQ – Plain answers for a smooth property transfer in Greece

Why appoint Katsouris Engineering for your property transfer

We provide end-to-end file management: measured surveys with 3D Laser Scanning, square-meter harmonization, legalizations, EPC issuance, HTK compilation, and EGSA ’87 topographic plans. We pre-check the Cadastre for KAEK errors or encumbrances to avoid last-minute roadblocks. For complex cases, we prepare structural adequacy/strengthening studies and technical opinions for out-of-plan plots. Our deliverable to your notary is a complete, tidy, and consistent file, which shortens decision time. Ask us for a pre-transfer file audit and a clear, dated action plan.

The post Property transfer: 12 common mistakes that delay the deed appeared first on Katsouris Engineering.

Correct and timely registration of the HTK is not just a formal obligation; it guarantees that the property is fully legal and ready to be utilized, without the risk of hidden violations or missing documentation.

When the Building Identity Certificate is Mandatory

The Building Identity Certificate has now been established as mandatory for a series of cases related to the management and transfer of real estate. Every time a property transaction takes place, whether it concerns a residence, a commercial space, or a plot of land, the existence of an updated HTK is necessary in order for the contract to be completed.

In addition, when an owner proceeds with the legalization or settlement of unauthorized constructions, the HTK serves as the official file where the related changes are recorded. It is also required when a new building permit or small-scale permit is issued, ensuring that there is a complete record of the property and its development. Finally, its connection with other documents, such as the Energy Performance Certificate (EPC), makes it a tool that touches almost every aspect of real estate.

Overall, the completion and registration of the HTK is required in cases such as:

• Property sale (residence, commercial building, plot of land).
• Legalization or settlement of unauthorized constructions.
• Issuance of a new building permit or small-scale construction permit.
• Entry of data in the Building Identity Certificate for buildings that are about to obtain an Energy Performance Certificate (EPC).

Required Documents for the Building Identity Certificate

In order to correctly complete the HTK, a set of documents that reflect the actual and legal status of the property is required. At the top of the list is the building permit along with any revisions, since it forms the basic legal framework of the building’s existence. Equally important are the floor plans, sections, and architectural drawings, which accurately show the layout and features of the property.

The E9 tax form of the owner is also often required, to confirm that the details declared to the tax authorities match the actual property data. If an Energy Performance Certificate (EPC) has been issued, it is also included in the file, while the engineer issues a certificate of no violations or records any legalizations that have been carried out. Finally, property photographs are requested for full documentation, while in some cases a Structural Adequacy Study (SAS) is required, especially when the property includes violations that affect the load-bearing structure.

In summary, the main documents usually required are:

• Building permit and any revisions.
• Floor plans, sections, and architectural drawings.
• Owner’s E9 tax form (to confirm ownership details).
• Energy Performance Certificate (EPC).
• Engineer’s certificate of no violations.
• Property photographs.
• In certain cases, Structural Adequacy Study (SAS), as required by Law 4495/2017.

Registration Process in the TEE System

The completion of the HTK is carried out exclusively by an authorized engineer through the electronic system of the Technical Chamber of Greece (TEE). The process begins with the collection of all required documents, something that often requires cooperation with services or the retrieval of old files from the owner. The engineer then performs a detailed legality check to ensure that there are no discrepancies between the drawings, the permit, and the actual state of the property.

Once the material has been gathered and verified, the engineer logs into the electronic system and proceeds with the registration of all data, uploading the documents and filling in the relevant forms. The process is completed with the issuance of the HTK, which receives a unique identification number. This number accompanies the property in every future transaction, making the HTK a living and continuously updated file.

1. Collection of all required documents from the owner.
2. Legality check and identification of discrepancies.
3. Engineer’s login to the TEE system.
4. Registration of all documents and property details.
5. Issuance of the Building Identity Certificate with a unique number.

The Importance of the Building Identity Certificate for Owners and the Real Estate Market

The Building Identity Certificate is not simply another administrative document. It is a process that radically changes the way we deal with real estate in Greece. For decades, the lack of a central digital record resulted in countless ambiguities, omissions, and often serious problems during property transactions. The HTK fills this gap by creating a “lifetime file” for each building, bringing together all data from the original building permit to the most recent modifications.

For the property owner, this means greater transparency but also greater security. Having a complete and updated file ensures that the property is ready for any future transaction without surprises. On the other hand, the buyer has in their hands all the data on the actual condition of the property, which minimizes the risk of hidden issues.

Although the process may seem complex, in reality it is an organized workflow that, with the proper guidance from an engineer, can be completed smoothly. The key lies in the cooperation between the owner and the engineer, so that all documents are collected on time without omissions. In many cases, delays in completing the process are due solely to the difficulty of retrieving old documents.

It is also important to emphasize that the HTK is not a static document. It is a living file that must be updated with every new intervention or modification of the building. This ensures that the record always remains current, offering security not only to the owner but also to future buyers.

In the final analysis, the Building Identity Certificate is an investment in the value and transparency of the property. It embodies the philosophy that real estate is not just a means of housing or investment, but an asset that requires responsibility, accuracy, and consistency in its management.

Frequently Asked Questions (FAQ)

Contact Us

If you need support for the completion of the Building Identity Certificate, our team undertakes the entire process, from document verification to final registration in the TEE system.

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