What experts often keep quiet about: The real risks

There are dangers lurking in home renovations that hardly anyone talks about. While tradespeople and construction companies like to emphasize the benefits of renovation, they often fail to mention the risks that can cause significant costs and health problems.

Hidden defects that can be expensive

Hidden defects are often only discovered years after the home is purchased. Especially with older properties, the risk of encountering costly surprises is high. A poorly insulated roof can lead to significant energy losses that only become apparent after a heating season. Hidden moisture damage in the basement caused by leaky seals or defective drainage systems often only becomes apparent through mold growth or discolored walls.

Especially in older buildings, defects typical of the year of construction, such as outdated heating systems, electrical installations, or piping, can occur. Adequate thermal or soundproofing is also often lacking. A building inspector can help identify hidden damage such as moisture in the walls or dilapidated pipes early on.

Asbestos, Lead, and Mold: Health Risks

Pollutants pose a particularly dangerous risk. Asbestos is a risk in buildings constructed before October 31, 1993. Approximately 20 percent of all structures in Germany could contain asbestos – a total of approximately 35 million tons.

Inhaled asbestos fibers can cause serious illnesses such as asbestosis, lung cancer, or pleural cancer, with up to 30 years between inhalation and the onset of symptoms. Therefore, before any renovation work, it is essential to check for asbestos-containing materials. Mold infestation and other pollutants such as PCBs in paints are similarly problematic.

Why energy-saving renovations are often mandatory

Many homeowners overlook the fact that energy-saving renovations are often required by law. The Building Energy Act (GEG) obligates owners to undertake certain renovation measures. Starting in 2024, those who have purchased, inherited, or received an older building as a gift will be particularly affected – with a two-year implementation deadline after moving in.

The requirement covers three main areas: the insulation of the top floor ceiling, the insulation of water and heating pipes, and the replacement of oil or gas heating systems that are more than 30 years old. Failure to comply can result in fines of up to €50,000. Exceptions apply to long-term owner-occupiers built before 2002, listed buildings, or cases where the costs are economically unreasonable.

However, improperly implemented renovations can also create new problems. For example, over-insulating windows without adequate wall insulation can lead to increased mold growth.

The requirement covers three main areas: the insulation of the top floor ceiling, the insulation of water and heating pipes, and the replacement of oil or gas heating systems that are more than 30 years old. Failure to comply can result in fines of up to €50,000. Exceptions apply to long-term owner-occupiers who lived before 2002, listed buildings, or cases where the renovation is economically unreasonable.

However, improperly executed renovations can also create new problems. For example, overly good window insulation without adequate wall insulation can lead to increased mold growth.

Plan your home renovation without any unpleasant surprises

Careful planning is the key to the success of any home renovation. Without a clear structure, the renovation project quickly becomes a financial and time-consuming waste.

How to choose the correct sequence of measures

When renovating, the basic principle is: work from outside to inside and from top to bottom. This means:

• First roof and facade
• Next, windows and doors
• Third, electrical and plumbing installations
• Finally, interior work and flooring

This sequence prevents previously completed work from being damaged by subsequent steps. Particularly important: Before ordering a heating system, the insulation and windows must be determined so that the system can be correctly dimensioned.

What is often forgotten in planning

Why a restructuring plan makes sense

An individual renovation plan (iSFP) offers four key advantages: It provides an overview of the energy status of the home, enables forward-looking planning, empowers you to act quickly, and helps you make optimal use of subsidies.

The plan is created by a qualified energy consultant who, in two on-site appointments, first conducts an inventory and then discusses recommendations with you. The cost of an iSFP for a single-family home is between €1,600 and €2,100, with the Federal Office for Economic Affairs and Export Control (BAFA) covering 50 percent (up to a maximum of €650).

However, a renovation plan only represents a snapshot in time. The older it is, the less meaningful it becomes due to technical developments and fluctuating material and labor costs.

Cost trap home renovation: How to avoid mistakes

The financial challenges of home renovation are often underestimated—which turns many projects into real cost traps. However, with careful planning and the right knowledge, unpleasant surprises can be avoided.

How much does a house renovation really cost?

For a basic renovation of a roughly 50-year-old house, you can expect to pay between €500 and €600 per square meter. For a comprehensive energy-efficient renovation, the costs rise to €750 and €1,600 per square meter, depending on the initial situation and the desired energy efficiency standard. Renovations of older buildings start at a minimum of €1,200 per square meter.

In concrete terms, this means: For a 100-square-meter house, renovation costs can range between €60,000 and €160,000. The actual costs depend on the original condition of your property, the scope of the planned measures, and the quality of the materials used.

Using the cost calculator correctly

Cost calculators are indispensable tools for budget planning. The KfW Renovation Calculator, for example, provides valuable information after about ten minutes of data entry:

• An overview of your property's energy efficiency
• Recommendations for energy-saving measures
• An overview of approximate renovation costs
• The savings potential of individual measures
• Available funding options from KfW and BAFA
  

Typical mistakes in budget planning

The biggest mistake in home renovation is incorrect budgeting. A detailed budget should serve as a compass for your renovation work. However, many builders fail to plan for sufficient buffers for unexpected expenses.

Experts recommend setting aside at least 15 percent of the total budget as an emergency fund. Disposal costs are also often forgotten. Construction debris is classified as hazardous waste and must be disposed of properly – these costs can be significant.

Another common mistake: too much self-help. Many do-it-yourselfers overestimate their craftsmanship and work pace, which can lead to significant delays and possibly even construction defects.

Funding that many people don't know

Numerous funding programs are available for energy-efficient renovations. A total of over 5,000 funding programs exist for various renovation measures, which can cover up to 50 percent of the eligible costs.

The Federal Funding for Efficient Buildings (BEG) supports individual measures with a repayment subsidy of 20 percent, with a maximum funding amount of €60,000 – i.e., a maximum of €12,000. For a complete renovation to a KfW Efficiency House, you can receive a loan of up to €150,000, with the repayment subsidy reaching up to €67,500.

Important: Submit your funding application before hiring a specialist company. A common mistake is for owners to begin renovation measures before applying for a subsidy – this often leads to the subsidy being rejected.

Do it yourself or commission it?

Doing your own home renovations is a trend and can result in significant savings. With the right assessment of your own skills and the knowledge of when to call in professionals, nothing stands in the way of a successful renovation.

Which tasks you can do yourself

Ambitious DIYers can save about 15 to 20 percent of the total cost by doing the work themselves. The following are particularly suitable for beginners:

• Painting and wallpapering in living spaces
• Installing click-fit laminate and other simple flooring
• Garden design and outdoor areas

Those with skilled tradespeople can also undertake drywall work, tile laying, or even parquet flooring installation. However, you should realistically assess your abilities, as improper execution can lead to subsequent costs.

When specialist companies are indispensable

Certain jobs should only be done by professionals:

• Electrical installations and plumbing work – improper work can lead to loss of insurance coverage
• Heating technology and roof work
• Structurally relevant renovations

Remember: There are no warranties or guarantees for DIY work—you are responsible for everything yourself. Professionals also usually complete the work faster and more precisely.

How to find good craftsmen

The best place to start your search for competent tradespeople is within your personal circle. Ask friends, acquaintances, or neighbors for recommendations. If that's not enough, you can also:

• Specialized online platforms such as MyHammer or Blauarbeit, where tradespeople are rated.
• The local Chamber of Crafts, which lists qualified businesses.
• Google search for local tradespeople.

Always obtain at least three different quotes to identify price differences—they can be as much as 50 percent. Pay particular attention to guild-certified and master craftsmen, as these guarantee professional quality.

Conclusion

Renovating a home is undoubtedly a major challenge – both financially and organizationally. As we've seen, homeowners can expect costs of between €400 and €600 per square meter, although this amount can be significantly higher for energy-efficient renovations. However, unpleasant surprises can be avoided with careful planning.

The correct sequence of work – from outside to inside and from top to bottom – is particularly important. A customized renovation schedule provides additional guidance and helps you make the most of subsidies. Remember that energy-efficient renovations are often mandatory, not optional, and failure to comply can result in hefty fines.

Don't underestimate the risk of hidden defects and harmful substances such as asbestos or mold. These can not only cause significant additional costs but also endanger your health. Therefore, an assessment by a building inspector is recommended before major projects.

When considering whether to do the work yourself or hire a professional, you should realistically assess your capabilities. While painting or simple flooring can easily be done by yourself, electrical, plumbing, and structural work definitely belong in professional hands.

Ultimately, plan generously with your time and budget. A buffer of at least 15 percent of your total budget for unforeseen events isn't excessive caution, but rather necessary foresight. With this preparation, knowledge of the true costs, and the use of available funding programs, nothing stands in the way of your successful home renovation.

Key Takeaways

These key insights will help you successfully complete your 2025 home renovation without any unpleasant surprises:

• Calculate realistically: expect 400-600 euros per square meter for basic renovation plus 15% buffer for unforeseen events

• Check for harmful substances: Buildings built before 1993 may contain asbestos - preliminary examination by an expert is essential

• Observe the renovation obligation: Energy-saving measures are often required by law - failure to comply can result in fines of up to 50,000 euros

•  Planen Sie die richtige Reihenfolge: Arbeiten von außen nach innen und oben nach unten durchführen - verhindert teure Doppelarbeiten

• Plan the correct sequence: carry out work from outside to inside and top to bottom - avoids expensive duplication of work

• Limit your own work: Painting and flooring work can be done by yourself, electrical/plumbing/statics belong to professionals

Careful planning with professional advice is the key to success. Never underestimate the complexity of a home renovation—it's better to ask more questions than to have to correct costly mistakes later.

FAQs

Q1. What are the average costs per square meter for a home renovation?

For a basic renovation, you should expect to pay between €400 and €600 per square meter. For a comprehensive energy-saving renovation, the costs can rise to €750 and €1,600 per square meter.

Q2. What are the hidden risks of a home renovation?

Commonly overlooked risks include hidden defects such as moisture or dilapidated pipes, harmful contaminants such as asbestos or mold, and unexpected legal requirements for energy-saving renovations.

Q3. Why is the order of renovation work important?

The correct order—from outside to inside and from top to bottom—prevents damage to previously completed work during subsequent steps. This saves time and money.

Q4. What home renovation work can you do yourself?

Simple jobs like painting, wallpapering, or installing click-lock laminate flooring can often be done by yourself. However, complex or safety-related tasks like electrical or plumbing work should be left to professionals.

Q5. Are there funding options for home renovations?

Yes, there are numerous funding programs, especially for energy-saving renovations. These can cover up to 50% of the eligible costs. It is important to submit the funding application before work begins.

Reference

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