Brief definition
Usable floor area (NF) under WoFlV is the sum of areas of living and usable rooms in residential buildings. It is central to dwelling counts, comparability of housing offers, and many estimating metrics.
Distinction
NF is not identical to DIN 276 cost groups or to gross floor area (BGF). For tendering and BoQ, standards and cost-group assignment remain separate from pure living-area calculation.
Normraum relevance
In the Normraum room book, every area sits in one row with room number, use and the selected norm – WoFlV or DIN 277 – calculated from the as-built plan, with confidence score and source reference. Cost-group and BoQ assignment stay separate; Normraum supplies the checked area basis, not the estimate.