Step-Free Building 2026: Surcharge, DIN 18040-2 and KfW 159
Barrier-free building has become the standard in 2026: every fifth new build follows DIN 18040-2. We explain the key dimensions of the standard, the realistic extra costs of €12,000 to €48,000, the KfW 159 funding in detail (up to €50,000 loan) and which manufacturers offer their own barrier-free house line at a calculable price.
What does a barrier-free (barrierefrei) prefab house cost – and how large is the surcharge compared with the standard version? That is exactly the pricing question we answer here. The technical framework is set by DIN 18040-2; the KfW promotional loan 159 “Age-appropriate conversion” (Altersgerecht Umbauen) provides financial relief. You will learn which standard dimensions trigger which extra cost, how three floor-plan variants (bungalow, single-family house with an optimised ground floor, multi-generation house) differ in price, and what square-metre price you should reckon with for barrier-free house ranges. The most barrier-free building form is the single-storey bungalow – the complete overview is bundled in the prefab bungalow guide, and all the steps are explained in our guide to building a bungalow. A low-barrier solution with a care room is shown in the bungalow with a granny flat: floor plans.
Does the surcharge for barrier-free building pay off?
Short answer: For three buyer profiles the surcharge for barrier-free building pays off especially quickly: for families who want to keep their house for decades and avoid a later conversion when care becomes necessary; for clients with limited mobility who depend on a wheelchair, rollator or walking aid; and for investors whose barrier-free properties achieve a higher resale value. The new-build surcharge of €12,000 to €48,000 remains easy to budget for and can be co-financed at a 60 to 90 percent interest-reduced rate via the KfW loan 159. A subsequent conversion, by contrast, costs three to five times as much.
In pure arithmetic terms, forward-looking planning pays off: most of today’s 50- to 65-year-olds stay in their own home into old age. Anyone building today is financing a property for the coming 30 years – and every retrofit later costs a multiple of the original surcharge. A level-access shower, 90 cm wide doors and a full living area on the ground floor are therefore less a sign of age than a value-stable investment. Young families benefit on top: wide passageways for the pram, a trip-free garden access and less cleaning effort reduce everyday costs and hassle.
DIN 18040-2: which dimensions entail which surcharge
Short answer: DIN 18040-2 distinguishes two levels of fit-out with different cost effects: “barrier-free usable” as the lower-priced standard and “barrier-free and fully wheelchair usable” as the more expensive R-standard. What matters most for price is: clear door widths of 80 cm (standard) or 90 cm (R-standard), movement areas of 120 × 120 cm or 150 × 150 cm, threshold-free transitions with a maximum 2 cm change in height, a level-access shower with a 120 × 120 cm standing area, window sills of at most 60 cm, and switches and sockets at 85 cm height. Every additional centimetre costs material and floor area – and thus square-metre price.
DIN 18040-2: standard versus R-standard (wheelchair)
| Component / area | Standard | R-standard (wheelchair) |
|---|---|---|
| Clear door width | ≥ 80 cm | ≥ 90 cm |
| Door handle height | 85 cm standard | 85 cm standard |
| Movement area in a room | 120 × 120 cm | 150 × 150 cm |
| Movement area in front of sanitary fixtures | 120 × 120 cm | 150 × 150 cm |
| Threshold-free transitions | max. 2 cm | max. 2 cm |
| Shower | level-access 120 × 120 cm | level-access 150 × 150 cm |
| WC seat height | 46–48 cm | 46–48 cm |
| Washbasin height | 82–86 cm | wheelchair-accessible 67 cm |
| Window sill | ≤ 60 cm sight line | ≤ 60 cm sight line |
| Sockets / switches | 85 cm height | 85 cm height |
| Stairs (if present) | handrail on both sides | handrail + lift/platform |
Some of these dimensions also open the door to KfW 159 funding and thereby indirectly lower your financing costs. Anyone who implements the full R-standard combines the grant levels “barrier reduction standard” and “barrier reduction standard 2” and thus exploits the maximum funding amount. You can see which square-metre prices the individual manufacturers charge for barrier-free versions in the provider comparison.
Three floor-plan concepts with their surcharge compared
Short answer: With the barrier-free prefab house, three floor-plan types dominate that clearly differ in price: the single-storey bungalow (all rooms on the ground floor, wheelchair-suitable, least conversion effort), the single-family house with an optimised ground floor (sleeping, bathroom and kitchen at ground level, upper storey optional) and the multi-generation house (two residential units, one barrier-free on the ground floor, one via lift on the upper floor). Each variant carries a different surcharge over the standard house price – from the almost cost-neutral bungalow to the elaborate two-unit concept.
- Bungalow 110–150 m²: everything on one level, wheelchair-suitable without stairs. Needs a larger plot (≥ 600 m²), which increases plot costs. House surcharge only €0–8,000.
- Single-family house with ground-floor optimisation 130–160 m²: sleeping, bathroom and kitchen at ground level, upper storey for children or hobbies, lift shaft preparable. Extra cost €12,000–25,000.
- Multi-generation house 180–250 m²: two units, one of them barrier-free – e.g. a parents’ flat below, family above. Highest surcharge of €25,000–48,000, but two usable units.
In pricing terms the bungalow is often the most attractive: people from age 55 are in strong demand for it because the house surcharge stays minimal. It does require more plot area, but with only one storey it delivers the same living space as a two-storey single-family house. A modern, single-storey variant is presented in the guide to a bungalow with a flat roof. You will find prices and models in the bungalow hub. Specific barrier-free floor plans are listed in the floor-plans section; ideas specifically for the bungalow are bundled in the guide to bungalow floor plans & ideas. Anyone planning two residential units will find the right basics in the guide to building a multi-generation house, in planning a granny flat and in the guide to the bungalow with a granny flat.
The barrier-free bathroom: where costs rise and where you save
Short answer: No room becomes as noticeably more expensive in barrier-free building as the bathroom. DIN 18040-2 requires a level-access shower of 120 × 120 cm (R-standard 150 × 150 cm), a WC with a 46–48 cm seat height and 90 cm of lateral movement area, for wheelchair use a wheelchair-accessible washbasin (top edge 80 cm, legroom 67 cm), a single-lever shower fitting, and support rails at the WC and shower per DIN 18040-3. The extra cost over a standard bathroom is €6,000 to €14,000 per bathroom, depending on the version.
Cost tip: a wall-mounted WC with a height-adjustable holder causes only about €250 in surcharge, but saves you a complete bathroom conversion if care becomes necessary. It is likewise worth planning wooden or metal cross-members into the wall cross-section now for later support rails (the so-called drywall reinforcement). This preparatory work costs €80 to €150 per fixing point and later saves €1,500 to €3,000 in chiselling and tiling work.
Prepare inexpensively instead of retrofitting expensively later
You can prepare a bathroom cost-effectively to be barrier-free “for later” without it becoming visible: pre-planned fixing points in the wall, a threshold-free shower tray, slightly wider door frames. Everyday life stays unchanged – if care becomes necessary, you save yourself the €15,000 to €25,000 of a subsequent conversion. Prefab house manufacturers such as KAMPA, FingerHaus or Bien-Zenker offer this “adaptable bathroom” as a standard option at a manageable surcharge.
Obtain fixed-price offers for barrier-free house ranges
At least 12 of the 140 manufacturers in our detailed comparison offer their own barrier-free house range in 2026 – with DIN-18040-2-compliant equipment, a transparent surcharge and KfW 159 application handling. We will arrange three suitable offers for you to compare.
KfW 159 “Age-appropriate conversion”: how to reduce your financing costs
Short answer: In 2026 the KfW programme 159 makes both the barrier-free new build and the conversion cheaper. It provides an interest-reduced loan of up to €50,000 per residential unit, with unscheduled repayments free of charge at any time. The prerequisite is DIN-18040-2-compliant planning or at least five recognised measures (widening doors, a level-access shower, support rails, threshold-free transitions, stairlift preparation). Because the interest rate lies well below a regular construction loan, the programme noticeably lowers your monthly burden. You must apply for it through your bank – mandatorily before signing the contract.
Both individual measures and complete standards are eligible for funding. For a new build, the following cost-relevant measure packages can be combined with one another:
- Paths & accesses: threshold-free house entrance, ramp instead of a step, sufficiently wide access path.
- Doors: clear width ≥ 80 cm (standard) or ≥ 90 cm (R-standard).
- Sanitary: level-access shower, wheelchair-accessible washstand, WC with support rails.
- Movement areas: 120 × 120 cm (standard) or 150 × 150 cm (R-standard) in all main living rooms.
- Internal circulation: wide staircase with handrail, lift or platform lift, preparation for sliding doors.
- Electrical equipment: switches and sockets at 85 cm height, smart lighting with motion detection, emergency-call preparation.
Which manufacturers offer barrier-free ranges – and at what price
Short answer: In 2026 at least 12 of the 140 manufacturers in our detailed comparison offer their own barrier-free house range with a stated surcharge: Bien-Zenker (“Concept-L”), Schwabenhaus (“SmartHome50plus”), KAMPA (“Bungalow Generation”), FingerHaus (“MEDLEY-Generation”), OKAL (“Bungalow”), Hanse Haus (“Single Floor”), Schwörer (“Bungalow”), Streif (“Bungalow Concept-G”), Town & Country (“Bungalow 92”), Heinz von Heiden (“Bungalow”), DAN-Wood (“Bungalow”) and Allkauf (“Bungalow Easy”). The offers differ greatly in standard equipment, surcharge and possible KfW options – so a price comparison always pays off.
You should check these cost-relevant points when comparing prices:
- Are door widths of 80 or 90 cm standard? (A subsequent door surcharge is often €250–600 each.)
- Is the level-access shower included in the price or does it cost extra?
- Are movement areas of 120 × 120 cm maintained in the bathroom, WC and bedroom at no extra cost?
- Is the handrail on both sides of the staircase included in the base price?
- Can a lift shaft be prepared cost-effectively for later installation?
- Does the manufacturer offer the KfW 159 application service (at least a BAFA energy consultant)?
Outdoor area and garden: the frequently overlooked cost items
Short answer: The outdoor area tends to be forgotten in budget planning, yet it decides the level of barrier-freedom – and additional costs. DIN-compliant means: a threshold-free transition from living room to terrace (max. 2 cm change in height), path widths of at least 120 cm (rollator) or 150 cm (wheelchair), low-joint solid surfaces (classic paving is unsuitable, concrete or natural stone is better), path lighting with motion detection, and seating every 30 m. Garden doors should have the same clear width as internal doors, which slightly raises the material price.
A sufficient roof overhang protects the entrance from the weather – important with limited mobility because unlocking takes longer. Smart door opening via smartphone, numeric code or fingerprint (see the smart-home guide) complements this for comparatively little money. For gardening, raised beds with a working height of 80 to 90 cm are ideal, comfortably reachable while standing or sitting.
Price verdict 2026: which measures pay off – and which do not
Short answer: These no-regret measures pay off in every new build because they cause little or no surcharge at all: 90 cm doors instead of 80 cm, a level-access shower, drywall reinforcement for later support rails, sockets 50 cm above the floor, a washbasin with prepared legroom, wide outdoor paths and a reserved area for a later lift shaft. The full R-standard pays off especially with a concrete need for care or mobility: the surcharge of €25,000 to €48,000 is co-financed at a 60 to 90 percent interest-reduced rate via the KfW loan 159.
As a rule of thumb: barrier-free preparation makes the new build only 5 to 15 percent more expensive per measure – in an existing building the same retrofit costs three to five times as much. Anyone who wants to live in the house for 30 years or longer therefore builds in R-standard doors, threshold-free transitions and the adaptable bathroom right away and saves on balance. Cross-generational use via a multi-generation house pays off especially if a larger single-family house is planned anyway: the second unit becomes barrier-free with comparatively little KfW effort. Anyone who wants to provide a multi-storey house with permanently threshold-free access will find the options in the guide to a house with a lift.
Compare barrier-free building, KfW 159 and fixed price
Three manufacturers with a barrier-free house range will prepare fixed-price offers for you including KfW 159 application handling. The surcharge and funding are broken down transparently – free and without obligation.
Building without thresholds – common searches at a glance
Threshold-free living from the start
Building barrier-free means planning the floor plan, doors, bathroom, kitchen, entrance area, movement areas and thresholds early – and factoring in the surcharge. Also point out possible funding.
What does your dream house really cost?
Request suitable quotes from vetted manufacturers for free and compare the prices per square metre for your construction project.
Compare house prices nowImportant questions briefly explained
The most common price questions around Step-Free Building 2026 – answered concisely by the Prefabricated House editorial team (as of 2026).
