That rough range covers a complete renovation of an apartment or house: new building services, new bathrooms, reworked surfaces and, in most cases, changes to the floor plan. Where a specific project lands within it depends mainly on the condition of the existing fabric, on how much of the plan you change and on the level of specification.
We give the number first because it is the only one anyone can quote responsibly without having seen your apartment. The rest of this article explains why the range is so wide and what moves your project up or down within it. We write as planners for renovation in Berlin and on Mallorca: we read trade quotes and take responsibility for how the build runs. We do not sell fixed-price packages.
What the 1,500 to 3,000 € per square metre includes
The 1,500 to 3,000 € per square metre (as of 2026, rough range) refer to a full renovation. By that we mean a project stripped back until the load-bearing structure and the raw floor are visible. Electrical and plumbing services are renewed, bathrooms rebuilt from scratch, floors taken up and relaid, walls opened or added, doors and surfaces reworked or replaced. Afterwards the property meets current technical standards and its service life starts again from zero.
Cosmetic refurbishment is not included. If the services, the bathroom and the floor plan all stay as they are, and the work is limited to painting walls, sanding floors and swapping individual elements, the costs are in an entirely different order of magnitude. We deliberately do not quote a separate range for that, because such work depends so heavily on the individual case that any blanket figure would mislead. Costs jump as soon as the first pipe is touched or the first wall is opened. From that point we cost the project like a full renovation, even if the scope looked smaller at the outset.
In between sits the partial renovation, which fully renews individual areas, typically the bathroom and kitchen, and leaves the rest largely as it is. It still costs more than the matching fraction of a full renovation, because site set-up, dust protection, coordination and the junctions with the existing fabric come up almost unchanged. If you are working on several rooms anyway, have the full renovation costed too, since per square metre it can come out lower.
Why two 120-square-metre apartments in the same building cost different amounts
This is the case we explain most often. Two apartments, same layout, same floor, same year of construction, and the cost estimates are far apart. The reasons are things you cannot see on a viewing.
One apartment was renovated once in the nineties and has usable risers and a screed that can stay. The other is original, with timber joist ceilings, old gas pipes, a bathroom squeezed into a corner as an afterthought, and a floor build-up whose height does not suit the planned underfloor heating anywhere. Same area, same address, and two very different building sites.
Then there is what the owners want. An open kitchen that means removing one non-structural wall is a different job from an open kitchen that needs a beam inserted into a load-bearing wall. Whether a level-access shower works in an Altbau depends mainly on the height of the floor build-up. That is why we only give a figure after surveying the property.
The five biggest cost drivers in an Altbau
First, the condition of the fabric, meaning whatever turns up behind the walls and under the floors. Berlin Altbau buildings are over a hundred years old and have been altered repeatedly, often without records. Damp at the base of walls, dry rot, decayed ceiling joists above an old bathroom, electrics from three eras layered on top of each other, hazardous substances in old adhesives and paints. None of this is unusual, and no visual inspection finds it reliably. So we open up and test the critical spots early in the design phase. Surprises then turn up before construction starts, rather than on site where they also cost time.
Second, building services. Electrics, water, drainage, heating, ventilation and data cabling are rarely in a state that supports modern use. Renewing them is expensive because the work is messy: chasing into solid masonry, core drilling through ceilings, coordination with the building's risers, which often belong to the owners' association rather than to you. You see none of it in the finished result, yet it is one of the largest items in the budget.
Third, the bathroom. Per square metre it is the most expensive room, because waterproofing, pipe routing, tiling, sanitaryware, fittings, ventilation and electrics all come together in a few square metres. For a bathroom in a Berlin Altbau renovation we work with roughly 25,000 to 60,000 € (as of 2026, rough range). The spread comes less from size than from decisions: level-access shower and recessed elements, natural stone or ceramic, the level of the fittings, a freestanding tub, underfloor heating, niches and bespoke pieces.
Fourth, how much you change the floor plan. Moving walls in an Altbau rarely involves only demolition and rebuilding. As soon as load-bearing elements are involved, you add structural engineering, calculations, beams, temporary support and in many cases a permit, and that work moves right to the front of the construction sequence. A project that keeps most of the existing plan and opens it in one or two places costs noticeably less than one that rearranges it completely.
Fifth, the level of specification. It is the only driver you control entirely, and it decides whether a project sits at the lower or upper end of the range: floor material, doors and frames, bespoke joinery instead of standard furniture, fittings, lighting, ironmongery. These decisions belong in the design phase. As long as nothing has been ordered, they can still be changed.
How heritage listing and the owners' association affect costs
If the building is listed, the renovation does not automatically become expensive, but you have fewer decisions to make freely. Windows, doors, stucco, historic floors and the facade need approval, elements are often reconstructed rather than replaced, and the effort shifts from materials to craft and design work. That takes time, and on a building site time costs money.
The same applies within an owners' association. Anything that touches communal property, meaning risers, facade, windows, load-bearing elements and often the balcony level, requires a resolution. You do not set the date for it alone, and it has to be built into the programme. Which approvals and consultations a Berlin Altbau actually requires, and in what order, we set out in Renovating a Berlin Altbau: permits and process.
How the construction period affects the budget
For a whole project we typically work with 6 to 12 months including design and construction (as of 2026, rough range). Some projects are quicker and some take longer, so we give a range rather than a promise. The construction phase alone of a full renovation starts at 4 to 6 months and can run longer.
Speed is partly a budget question: some contractors work faster and charge more for it. If you have a fixed move-in date, you pay for that certainty, and it should be in the costing openly from the start. Delay costs money too, when rent runs in parallel or storage has to be paid for.
Then there is the design. Decisions made or changed during construction cost more than the same decisions three months earlier, because they trigger variations, waiting time and reordering. The most effective way to keep costs in check is to have the design finished before work starts.
The four most common reasons budgets are exceeded
In our experience an expensive tap is rarely the reason. Budgets are exceeded in four places.
First, through incomplete quotes. A quote that looks cheap because items are missing becomes expensive through variations, and that only shows once the site is running. How to spot this in advance is set out in Red flags in contractor quotes: how to compare.
Second, through the existing fabric, when nothing was opened up and the estimate rests on assumptions. Third, through changes during construction, when many small wishes add up to one large sum. Fourth, through the split between construction and furnishing: kitchen, furniture, lighting, curtains and appliances are often treated separately and are missing from the construction budget, even though they have to be paid for. That is why we put them in the same schedule from the start.
Cost drivers at a glance
The table below shows what the range depends on and which decision typically comes up at each point. It does not replace a costing, but it shows where you can influence the costs of your project.
| Cost driver | Affects | Typical decision |
|---|---|---|
| Condition of the fabric | Extent of strip-out, structure, drylining, programme, risk of variations | Opening-up works before costing, or costing based on assumptions |
| Building services | Electrics, water, drainage, heating, ventilation, coordination with risers | Full renewal or reuse of existing pipework and cabling |
| Bathroom | Highest cost per square metre in the whole project | Number of bathrooms, level-access shower, materials, level of fittings |
| Depth of floor plan changes | Structure, calculations, permits, sequence and duration of the build | Keep most of the existing plan and open it selectively, or rearrange it |
| Level of specification | Position within the range, share of joinery and bespoke work | Standard or bespoke, natural material or alternative |
| Heritage listing and owners' association | Room for decisions, coordination effort, dates in the programme | Reconstruct rather than replace, obtain resolutions early |
| Time and schedule pressure | Price level of the construction work, variations, double costs while building | Pay for a fixed move-in date, or set a calmer programme |
How we prepare the cost estimate
With us you get a number before you commit. It starts with a survey on site: measurements, condition, building services, floor build-up, and the points where we recommend opening up. Then we agree the scope, meaning which areas are fully renewed, where the floor plan changes, and what level of specification you actually mean when you say it should be high quality.
On that basis we produce a cost estimate priced with our own network of trades, firms we have been building with in Berlin for years and whose prices we know. The number therefore comes from quotes for comparable work. An online calculator works with averages instead. Construction and furnishing sit in one schedule, so you see the total rather than only the building part.
You receive this estimate before you commit to a design phase. That is what the CARLO Design Project Check is for: you know the scope, timeframe and order of magnitude of the costs before you decide. How we then design the renovation and run it on site is described on our renovation page.
Frequently asked questions
What does an Altbau renovation cost per square metre?
For a full renovation of a Berlin Altbau we work with roughly 1,500 to 3,000 € per square metre (as of 2026, rough range). The lower end applies to apartments in usable condition, with the floor plan largely retained and a restrained specification. The upper end applies when the fabric needs extensive work, the plan is rearranged, several bathrooms are created and bespoke work makes up a large share. A reliable figure for your apartment only emerges after a survey.
How long does a full renovation take?
For a whole project including design and construction we typically work with 6 to 12 months (as of 2026, rough range). The construction phase alone of a full renovation starts at 4 to 6 months and can run longer. There are exceptions in both directions, so we give a range rather than a promise. Part of the duration is also a budget question, because some contractors work faster and charge more for it.
What is the most expensive part of a renovation?
Measured per square metre it is the bathroom, because waterproofing, pipework, tiling, sanitaryware and electrics all come together in a small area. For a bathroom we work with roughly 25,000 to 60,000 € (as of 2026, rough range). Measured against the total, it is usually the building services, meaning the complete renewal of electrics, water, drainage and heating. You cannot see them in the finished room, yet they are one of the largest items in the budget.
Can you live in the apartment during the renovation?
For a full renovation we advise against it. Once services, bathroom and floors are being renewed, water, power and heating are unavailable for long stretches, and dust and noise cannot be confined to individual rooms on a site of that kind. An occupied apartment also slows the build, because trades cannot work in parallel. For a clearly bounded partial renovation, such as a single bathroom in an apartment with a second one, staying put is often possible. Settle this question during planning, because temporary accommodation belongs in the budget.
Your next step
Where your apartment sits within this range can only be judged from the property itself. After a conversation and a visit on site, you receive a realistic cost estimate from us, priced with our network of trades, before you commit to anything. Get in touch and we will come and look at your Altbau.