Repair and modernisation needs deferred over the years often add up unnoticed – until the roof, heating or wiring all call for investment at the same time. This is exactly what the term renovation backlog (Sanierungsstau) describes. For owners it is decisive when selling, because it influences the achievable price, the negotiation and the legal duties on a change of owner. We explain to you in plain terms how to recognise a renovation backlog, what it means for the value of your property, which modernisation duties the Buildings Energy Act (GEG) provides for, and how to weigh up renovating against selling in the current condition.
What does renovation backlog mean?
One speaks of a renovation backlog (Sanierungsstau) – often also called a maintenance or modernisation backlog – when necessary repairs, restorations and modernisations have been left undone on a property over a longer period and the resulting need has piled up. What is meant is not individual cosmetic repairs, but above all substantial and functional defects in building components and building services that involve a noticeable need for investment.
The term is shaped by economics and building technology; it is not an independent legal term. In valuation, however, the costs of clearing a renovation backlog are regularly taken into account as a value-reducing factor. It is typical for technical deficits and energy weaknesses to coincide: an old heating system, uninsulated components and windows that have aged cause not only a need for repair but also high energy costs. Anyone who assesses the condition of their property early and honestly can plan more precisely when selling.
Typical problem areas – how to recognise a renovation backlog
A renovation backlog rarely shows up in a single place. Experience shows these areas are the most important indicators:
- Roof: water stains on ceilings or in the loft, damaged or slipped tiles, a missing or porous sub-roof membrane, corroded gutters and downpipes as well as inadequate insulation point to a need for action.
- Heating and building services: a very old heat generator, high consumption, uneven heat distribution, frequent faults and outdated control technology are clear warning signs. The age of the boiler is particularly telling here.
- Wiring: old screw fuses, a missing residual-current circuit breaker, too few sockets, visible makeshift solutions and recurring outages indicate a system in need of overhaul.
- Windows: draughts, condensation, fogged panes between the glass layers, brittle seals and stiff fittings point to high heat losses.
- Facade and insulation: flaking render, cracks, cold interior walls, thermal bridges and high heating costs are typical signs of missing or inadequate insulation.
- Damp and cellar: a musty smell, mould, salt efflorescence, damp plinth areas and wet cellar walls point to moisture problems that should be taken seriously.
- Pipes and lines: corrosion, pressure drops, discolouration of the water, lime deposits, leaks and uninsulated pipes in unheated rooms are further clues.
If several of these points occur together, experience shows there is a relevant renovation backlog.
Consequences for value and sale price
A renovation backlog has an effect on two levels: on the achievable price and on the marketing period. Buyers factor in the renovation costs to be expected, the risk of hidden defects and the time required for the work – and deduct these points from the price. In market-value assessment the costs of clearing the defects are often taken into account directly as value-reducing.
There are deliberately no flat-rate percentages. How large the discount turns out to be depends on the scope and urgency of the measures, on the location and on the local market environment. The larger the interventions on the roof, heating, wiring or in the case of moisture damage, the more strongly this also affects financability for buyers – and the longer the marketing can take. At the same time, in Düsseldorf and in many locations in North Rhine-Westphalia there is a noticeable demand for properties with development potential. What is decisive is a realistic, comprehensible valuation: anyone who presents the condition transparently achieves, in our experience, more stable results than with an inflated entry price that later has to be corrected.
Renovation backlog when buying: negotiation, surveyor and reserve
From the buyer's point of view, a renovation backlog is initially a negotiating topic. A negotiation is sound when it is based on reliable figures – for example concrete cost estimates or a survey. Flat-rate estimates, by contrast, are easy to challenge.
- Surveyors and experts: an independent building survey helps to identify hidden defects and follow-up costs – especially with the roof, cellar, damp, wiring and heating. In this way the renovation need can be quantified seriously.
- Maintenance reserve for condominiums: when buying an apartment within an owners' association, it is worth looking at the maintenance reserve (Erhaltungsrücklage). Under Section 19 of the Condominium Act (§ 19 WEG), the proper upkeep of the common property and the accumulation of an appropriate maintenance reserve are part of proper administration. If the reserve is too low, special levies loom when larger measures are due.
- Check the documents: minutes of the owners' meetings, the business plan, service-charge statements and any arrears give indications of a renovation backlog in the common property and of the financial situation of the association.
For sellers, conversely, the following applies: anyone who communicates defects openly and backs them up with documents creates trust and often shortens the negotiation.
GEG duties on a change of owner: heating and retrofitting
On a change of owner, certain duties of the Buildings Energy Act (GEG) become relevant. You should know these rules, because they make the renovation need calculable for buyers:
- Operating ban for old boilers (§ 72 GEG): boilers fired with oil or gas that were installed before 1 January 1991 may no longer be operated. Newer boilers may no longer be operated after 30 years have elapsed. Low-temperature and condensing boilers, among others, are exempt. In addition, fossil-fired boilers may run on fossil fuels at the longest until the end of 31 December 2044.
- Insulation of the top storey ceiling (§ 47 GEG): uninsulated top storey ceilings must be insulated so that the heat transfer coefficient (U-value) does not exceed 0.24 watts per square metre and kelvin; alternatively, the roof above can be insulated. For an owner-occupied residential building with no more than two dwellings, only the new owner has to fulfil this duty – and within two years of the transfer of ownership.
- Insulation of pipes (§ 69 GEG): previously uninsulated, accessible heat-distribution and hot-water pipes that do not lie in heated rooms must be insulated.
In addition, there is a conditional duty under § 48 GEG: anyone who renews larger parts of an external component anyway – for example the facade or the roof – must comply with the minimum energy requirements in doing so. The GEG is currently being revised politically; the version of the act in force at the time is always decisive.
65-percent duty for new heating systems and the energy certificate
If a heating system is newly installed, the central requirement of § 71 GEG applies: a newly installed heating system must in principle generate at least 65 percent of the heat provided from renewable energies or unavoidable waste heat. This is deemed fulfilled, among other things, by connection to a heat network, by a heat pump, a direct electric heater, a solar thermal installation or certain hybrid and biomass solutions.
For existing buildings, this duty is tied to municipal heat planning. In municipalities with more than 100,000 inhabitants (reference date 1 January 2024), the requirement applies at the latest from 1 July 2026, in smaller municipalities at the latest from 1 July 2028 – unless a corresponding municipal decision is taken beforehand. For owners in Düsseldorf, the earlier deadline is therefore decisive. Before installing a fossil-fired heating system, advice is moreover required.
Independently of the renovation backlog, the energy certificate duty under § 80 GEG applies on a sale: the seller or the engaged agent must present interested parties with the energy certificate at the latest at the viewing and hand it over after conclusion of the contract. The energy certificate makes energy weaknesses visible and is therefore a building block of honest marketing.
Renovate or sell in the current condition – and how we accompany you
Whether a renovation before the sale is worthwhile cannot be answered across the board. Renovating speaks for itself when targeted measures clearly improve the achievable price and the circle of buyers and the investment is in proportion. Selling in the current condition speaks for itself when the effort is high, the result uncertain or time is short – because many buyers want to renovate to their own ideas anyway and factor that in. Often, selling in the current condition is the clearer and lower-risk route, because you do not have to make an advance outlay and do not have to give a guarantee for the success of individual measures.
We assess your property realistically – even when there is a renovation backlog. We neither talk the condition up nor down, but classify it comprehensibly and show you the options. As an arm of Wolfgang Richter GmbH, we have accompanied owners in the Düsseldorf and North Rhine-Westphalian market for more than six decades. Over the years, a grown network with more than 20,000 contacts has emerged, which helps us to bring properties and suitable interested parties together discreetly – on request also in a confidential marketing away from the large portals. Whether selling in the current condition or an accompanied route: we take every step together with you.
