Do I have to renovate before selling?
In owner conversations these three things almost always get knotted into a single lump of worry: retrofit duty, boiler replacement, energy certificate. Here they lie separate, with the references, so you can check them.
What changed on 29 July 2026?
The building energy act (Gebäudeenergiegesetz, GEG), popularly known as the heating law, has been called the building modernisation act (Gebäudemodernisierungsgesetz, GModG) since 29 July 2026. It was not replaced: the amending act of 23 July 2026 (Federal Law Gazette BGBl. 2026 I No. 226, issued on 28 July 2026) swapped the title and changed the text in many places. It remains the same act, promulgated on 8 August 2020 (BGBl. I p. 1728). That is more than a formality: anyone searching for a “GModG of 29 July 2026” finds nothing, because the act itself is dated 8 August 2020. Some sections were renumbered, and two of the best-known duties were deleted outright.
| Topic | Until 28 July 2026 (GEG) | Since 29 July 2026 (GModG) |
|---|---|---|
| Insulating the top-floor ceiling | Section 47 GEG | Section 35 GModG, renumbered |
| Insulating the heating pipes | Section 69 GEG | Section 69 GModG, with new subsections (3) and (4) |
| Boiler replacement after 30 years | Section 72 GEG | deleted |
| 65 percent renewable energy | Section 71 GEG | deleted, replaced by the staged quota in Section 43 GModG |
| Energy certificate in the advertisement | Section 87 GEG | Section 87 GModG, unchanged |
Anyone still reading today that a buyer must swap the boiler within two years is reading a text written before the summer. That is the practical reason for this page: what people know at the kitchen table lags behind the law, on both sides of the table.
Which retrofit duties remain?
Two, and both are comparatively small. They attach to the building, not to the person selling it.
Top-floor ceiling (Section 35 GModG)
It must be insulated if it does not meet the minimum thermal protection under DIN 4108-2: the heat transfer coefficient must not exceed 0.24 watts per square metre and kelvin. Alternatively it is enough to insulate the roof above it to the same standard. What is meant is the accessible ceiling towards an unheated loft, not a converted attic storey.
Heating and hot-water pipes (Section 69 GModG)
Accessible pipes running outside heated rooms that have not been insulated so far must be insulated. In practice that means the pipework in the cellar. It is the cheapest measure in the whole catalogue and a weekend's work.
What no longer belongs on the list
Replacing constant-temperature boilers more than 30 years old. That duty sat in Section 72 GEG and was deleted with effect from 29 July 2026. If you hear it raised in a negotiation as an argument against your price, the other side is working from an outdated source.
Who has to retrofit, seller or buyer?
A special rule applies to the classic pre-war family house in Dresden. It is the reason this page exists at all, and it is misreported almost everywhere.
The cut-off date rule and its trap
For a residential building with no more than two flats, one of which the owner occupied on 1 February 2002, the insulation duty only has to be met in the event of a change of ownership after that date, and it is the new owner who has to meet it. The deadline is two years from the first transfer of ownership after 1 February 2002 (Section 35(3) GModG; for pipe insulation, Section 69(3) and (4) GModG).
The word “first” is almost universally skipped. If the house has already changed hands once since February 2002, the window has been used up: it does not start again on the next sale, and the duty already sits with today's owner. The line “the buyer has to do that, he gets two years” only holds for the very first sale after the cut-off date.
Cut-off date 1 February 2002
The protection only covers residential buildings with no more than two flats, one of which the owner occupied on that day. A house that was let is never covered.
First transfer of ownership
The two-year deadline starts with the first change of ownership after the cut-off date, once only. No later sale resets it.
Economic limit
For owner-occupied houses with no more than two flats the duty falls away in so far as the expenditure cannot be recouped by the resulting savings within a reasonable period (Section 35(4) GModG).
For the negotiation that means: establish before the first viewing when the house last changed hands. That single piece of information decides whether the insulation duty is the buyer's problem or has long been yours.
Does a new heating system have to go in before the sale?
No. A working heating system may keep running, repairs are permitted, and a duty to replace it purely because of its age has not existed since 29 July 2026. It looks different when a system is actually replaced: if a system fired with gas, heating oil or LPG is installed in an existing building after that date, Section 43 GModG imposes a progressively rising quota of renewable or low-carbon heat.
10 %
from 1 January 2029
15 %
from 1 January 2030
30 %
from 1 January 2035
60 %
from 1 January 2040
The quota can be met, among other routes, by a solar thermal system. The former 65 percent rule no longer applies. For your sale that is a relief: the buyer does not have to touch the heating system in order to move in, and that argument belongs in your sales conversation.
The energy certificate remains your duty
This is the one duty that falls on the seller personally, and it carries a sanction.
In the advertisement (Section 87 GModG)
Type of certificate, final energy demand or consumption, the main energy sources for the heating, year of construction and energy efficiency class.
At the viewing (Section 80 GModG)
Show the certificate or a copy at the latest by then, and without undue delay on request. Displaying it clearly on site is enough.
After the purchase contract (Section 80 GModG)
Hand the original or a copy to the buyer without undue delay.
Fine (Section 108 GModG)
Breaches of the energy certificate duties are regulatory offences and can be fined up to 10,000 euros.
Which certificate is the right one, how long it is valid and how quickly you can get one is covered in the guide to the energy certificate when selling.
What the energy efficiency class costs you on the price
The legislator asks for little. The market asks for a lot. Buyers read the class in the listing and set the expected renovation costs against it before they ever turn up to a viewing.
| Energy efficiency class | Price discount in Dresden |
|---|---|
| A to C | no discount |
| D to E | 3 to 8 percent |
| F to G | 8 to 15 percent |
| H | 12 to 20 percent |
Renovate, or sell with the discount?
The honest comparison, the way I set it out at the kitchen table. The sum works when the discount you avoid is larger than the money you put in.
| Renovate before selling | Sell as it stands | |
|---|---|---|
| Capital tied up | 15,000 to 30,000 euros for a new heating system, plus insulation | none |
| When you see it again | at the notary appointment at the earliest, and only if the buyer pays for it | straight away, in the price |
| Effect on the price | avoids the discount of 8 to 15 percent | the discount is already priced in |
| Time lost | several months of building work before marketing starts | marketing starts immediately |
| Risk | cost overruns, trade availability, warranty | the buyer calculates with a buffer |
| Fits if | the heating is at the end of its life anyway and you have time | you have a reason to sell that will not wait |
In sought-after districts such as Striesen or Blasewitz, where the absolute figures are high, the sum tips towards renovating more often than it does in the surrounding towns: there the same boiler replacement costs the same amount but works on a smaller purchase price. What helps in either case: documentation. A buyer holding invoices, service records and the energy certificate calculates with a smaller buffer than one who has to guess.
What your house is worth as it stands
Before you think about renovating, you should know the starting figure: what is your house achievable for in your district, exactly as it stands today? On that basis you can work out whether a measure before the sale pays for itself, or whether the discount is the cheaper route.
Legal note: This page describes the state of the German building modernisation act (GModG) as at 27 August 2026 in general, non-binding terms. It does not replace legal advice. Whether a retrofit duty applies in your specific case depends among other things on the year of construction, the use, the number of flats and the ownership history, and should be checked before you commit to anything in a purchase contract. Immobilienpartner Sachsen operates as a real estate agent and does not provide legal services within the meaning of the German Legal Services Act (Rechtsdienstleistungsgesetz). The German version of this page prevails.
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