Buying an older house: correctly assessing value, renovation costs and GEG obligations

A row house from 1962, a farmstead from 1890, a Gründerzeit townhouse: Older houses have character, established locations, and often a price per square meter below that of new builds. The catch rarely lies in the visible. It lies in the structure, the renovation backlog, and energy-related obligations that only become apparent after the notarial appointment – and then blow the budget.

Therefore, anyone wishing to buy an older house needs three answers before signing: Is the asking price market-conforming? What is the house actually worth according to the ImmoWertV? And which burdens – structural and energy-related – are depressing this value? This article outlines the typical pitfalls and shows how a market value appraisal before purchase limits financial risk.

Buying an older house: why the purchase price is rarely the true value

The purchase price and the market value are two different figures. The purchase price is the result of an individual negotiation – shaped by supply, bidding pressure, time pressure, and the emotion triggered by a charming historic building. The market value, on the other hand, is the objectively comprehensible market value according to § 194 BauGB, derived in accordance with the standardized procedures of the Real Estate Valuation Ordinance (ImmoWertV).

For a newer, well-maintained house, both figures are close together. With a historic building, there is often a gap, because the asking price factors in the well-maintained first impression, but not the thirty-year-old electrical wiring behind the walls or the uninsulated roof. The seller sells the feeling, the buyer ultimately pays for the substance.

This is precisely why it pays to consult a valuer before making an offer. The page on local property valuation; how prices develop regionally is demonstrated by the Price Developments and Market Trends.

What is the house worth according to the ImmoWertV?

The market value of an existing house is derived in accordance with the Real Estate Valuation Ordinance (ImmoWertV) – depending on the property, via the sales comparison approach, the cost approach, or the income approach. For owner-occupied single-family or terraced houses, the sales comparison approach, supported by the cost approach, typically leads to the result.

The condition of the house is not a minor aspect, but directly influences the value in several respects:

• Remaining useful life: Modernizations extend it, a backlog of maintenance shortens it – and through the remaining useful life, the condition directly impacts the value.
• Age-related depreciation: The cost value is reduced by the age-related loss in value; a well-maintained and a neglected house of the same construction year are worlds apart here.
• Particular property-specific characteristics: Known structural defects, moisture damage, hazardous substances, or maintenance backlogs are treated as value-reducing factors – typically as a deduction equivalent to the required repair costs.
• Energy efficiency status: A weak energy standard reduces the price achievable on the market and, consequently, the market value.

The key lies in the division of responsibilities: Whether the roof structure is load-bearing or the source of moisture is determined by a building expert. As a real estate valuer, I determine the market value according to ImmoWertV and incorporate identified defects and renovation requirements as value-relevant factors into the valuation. The building condition is the finding; the market value is the derived figure – the figure you use for negotiation and financing.

The typical weak points of older houses – and what they cost

The renovation requirements for existing buildings usually follow a similar pattern. Seven trades account for the majority of the costs – and the larger the accumulated backlog, the more significant the deduction from the market value. The following figures are indicative magnitudes for 2026; they neither replace a contractor's quote nor the assessment of a building expert, but they provide the framework within which the value-reducing renovation expenditure falls.

As a rough rule of thumb from practice: houses built before 1930 may require renovation costs amounting to roughly half of the purchase price in total; for older existing buildings, it is often around twenty percent. The range is enormous – and it determines whether the purchase makes financial sense.

Building Modernisation Act 2026: the energy obligations that affect buyers

When purchasing an older house, not only the walls pass to the new owner, but also energy-related obligations. Three points are essential for the purchase decision.

The energy certificate must be presented by the seller at the latest during the inspection and handed over upon purchase. It provides an initial indication of the energy-related condition – with the demand-based certificate being more informative than the consumption-based one, as it is not dependent on the heating behaviour of previous owners.

The retrofitting obligations upon change of ownership are the point that many buyers overlook. Whoever acquires a single- or two-family house generally has two years from the entry in the land register to carry out certain measures: insulating the top floor ceiling or the roof to a U-value of 0.24 W/(m²K), as well as insulating accessible heating and hot water pipes. Important: The exemption that frees owner-occupiers from retrofitting applies only if they have been living in the house themselves since February 1, 2002. With the change of ownership, this exemption ceases to apply – the buyer inherits the obligation.

Regarding the heating system the situation has noticeably eased in 2026. The Building Modernisation Act, in force since July 29, 2026, has abolished the previous obligation to operate new heating systems with at least 65 percent renewable energy. Free choice of heating system applies again – heat pump, district heating, hybrid solution, biomass, or continuing with oil and gas. However, anyone installing a new oil or gas heating system from 2029 onwards must blend in increasing shares of climate-neutral fuels: 10 percent from 2029, 15 percent from 2030, 30 percent from 2035, and 60 percent from 2040. This significantly increases the operating costs of a fossil heating system over its holding period.

Regardless of any specific obligation, the energy efficiency of the property remains the largest operating cost factor. A poorly insulated house with an old boiler is expensive to maintain – and with the rising CO2 price on fossil fuels, it will become more costly year after year, even without an immediate replacement obligation.

From offer to a reliable budget

The actual budget comprises more than the purchase price. Four components must be aggregated before financing is secured.

For energy-efficient measures, there are grants and low-interest loans from KfW and BAFA – but these do not change the fundamental rule: the need must first be established before funding and financing can be arranged. Anyone who roughly estimates the renovation need instead of having it documented is building on sand.

How a valuation report protects your budget before purchase

A market value appraisal before signing answers the valuation question on a solid basis rather than based on intuition. Specifically, it provides:

• the market value according to ImmoWertV as an objective anchor for price negotiations instead of a perceived value;
• the value-reducing effect of the condition and deferred maintenance – i.e., the discount that the asking price should actually reflect;
• the classification of the energy efficiency standard and its impact on market and operating costs;
• a solid foundation for financing, equity planning, and – in case of dispute – for negotiations.

For the pure purchase decision, a short-form appraisal: faster and more cost-effective than a comprehensive market value appraisal, yet reliable enough to determine whether the price is justified. The prices for this are transparently listed under Condensed appraisal report: costs, whereas a full market value appraisal is recommended when the valuation must hold up against a bank, tax office, or court. Specifically for private buyers, the page Real Estate Valuation for Private Individuals the appropriate framework.

When buying a condominium, the risks shift to the service charge, the reserve fund and the owners' association – how to check these before purchase is shown in the article Buying a condominium: service charge, reserve fund and owners' association.

Checklist before the purchase decision

Before you submit a binding offer, these points should be clarified:

Those who can honestly answer these six points are buying with open eyes rather than on hope. And if you are unsure about the last point, you should clarify it before the notary appointment – not after.