Sloping Ceilings and Living Space — the 1 and 2 Metre Rule

The grading by clear height

Under a sloping ceiling not every square metre is worth the same. The Living Space Ordinance grades the weighting according to the clear height of the part of the room in question: [§ 4 nos. 1–2 WoFlV]

What matters is the finished state: measurement runs from the top of the finished floor to the underside of the finished sloping ceiling. [§ 3 (1) WoFlV] A screed laid later or a suspended ceiling reduces the clear height — and with it, potentially, the countable living space.

A worked example

A loft room is 5.00 m long and 6.00 m wide, giving 30 m² of floor area. The roof falls across the width. Measured out, this results in the following breakdown:

So 30 m² of floor area becomes 20.50 m² of living space — around a third less. It is precisely this difference that regularly leads to disputes where a brochure or tenancy agreement stated the plain floor area.

Why the knee wall matters so much

The knee wall is the low external wall on which the sloping ceiling sits. It shifts the entire slope upwards and thereby enlarges the zone with at least 2 metres of clear height.

The effect is substantial: with the same floor area and the same roof pitch, a house with a high knee wall can have considerably more countable living space in the loft than one without. Anyone comparing two seemingly similar properties should therefore look not only at the floor area but at the roof geometry.

Dormers work in a similar way: they raise the room precisely where the slope would otherwise be low, enlarging the fully countable zone accordingly.

What else to check in a loft

The height grading only applies once the room belongs to the living space at all. The prior question is always whether it meets the building law requirements for a habitable room [§ 2 (3) WoFlV] — depending on the state building code, for instance as to minimum height over a given proportion of the area, daylight, ventilation and a second escape route.

A converted attic loft without these prerequisites is an ancillary room and does not count at all, regardless of its height or the standard of the fit-out. The fundamentals are set out on the page Living space calculation under the WoFlV.

Common errors with lofts

• Floor area stated instead of living space. The most common error — and in a loft the most consequential.
• Only two zones formed. Anyone not recording the zone below 1 m separately inadvertently counts it at half.
• Shell dimensions used. Without screed and internal fit-out the clear height comes out too large.
• Dormers treated as a blanket case. Inside a dormer too, the height has to be actually measured.
• Building law admissibility not checked. A room not approved as habitable is not living space.

Frequently asked questions