Knowledge

The BGF is the sum of the floor areas of all floor levels including the construction: BGF = KGF + NRF. What counts, how it is measured and why the WoFlV has no BGF.

Distinction between DIN 277 (areas) and DIN 276 (costs): when each standard applies to areas and quantities.

Three rule sets, three purposes: DIN 277 for planning and benchmarks, WoFlV for residential rent, gif MF-GIF for commercial rental areas. Differences in measuring rule, counting and scope, with editions.

DIN 277:2021-08 structures a building's floor area: BGF = KGF + NRF, NRF = NUF + TF + VF. Definitions, calculation scheme, the R and S categories and the renamings since 2016.

The NRF is the floor area of all rooms without the construction, measured in clear dimensions: NRF = NUF + TF + VF. Definition, measuring rule, distinction from the former NGF and from living area.

The usable area is the part of the net room area that serves the building's purpose. The seven use categories NUF 1 to NUF 7 with examples and the distinction from TF and VF.

TF is the floor area for building services, VF the floor area for access, circulation and escape. Examples, allocation cases and their role in the room book.

An as-built plan documents the built state as of its plan revision; the survey checks it on site. Why old plans deviate and when a survey is needed.

Why the actual living area counts (BGH), how a screening checks contractual areas against plan areas and where a survey is needed afterwards.

What a check log must document so that automatically measured areas are traceable: source reference, standard and calculation rule, confidence per room, sign-off. Confidence is not accuracy.

A room book lists every room of a building with room number, floor, use and area under a named standard. Structure, HOAI classification and the fields CAFM and ERP imports expect.

Area calculation in the attic: living/usable area with sloping ceilings under WoFlV rules.

Definition of usable floor area under the Living Space Ordinance (WoFlV) for residential buildings and its distinction from BGF and DIN 276.

Balconies and loggias under WoFlV: when they count toward living area and typical planning evidence.

Basement and ancillary rooms under WoFlV: inclusion, deductions, and typical planning errors in area calculation.

Living area under WoFlV: determination rules, deductions, and differences from usable area and gross floor area.

Cost group 100 under DIN 276: preparatory site measures before construction start in cost planning.

Cost group 200 under DIN 276: land value, legal interests, and preparatory measures in cost planning.

Cost group 300 under DIN 276: load-bearing and non-load-bearing building structures in fee and cost planning.

KG 400 under DIN 276: technical building services — scope and relevance for quantity take-off.

Cost group 410 under DIN 276: piping systems and related quantity take-off in building services.

Cost group 420 under DIN 276: heating systems, heat distribution, and related BoQ items.

Cost group 430 under DIN 276: power and low voltage, cabling, and installation zones.

Cost group 500 under DIN 276: external works, landscaping, and open-space construction in fee and cost planning.

Cost group 600 under DIN 276: movable fittings, furnishings, and artwork-related costs in cost planning.

Cost group 700 under DIN 276: fees, ancillary costs, and risks outside pure building construction groups.

Overview of DIN 276 cost groups 100–700: structure, assignment, and role in fees and tendering.

Relationship between DIN 276 cost groups and HOAI service phases for architects and specialist planners.

AI surveying: software detects rooms, walls and openings in an as-built plan and calculates areas under DIN 277 or WoFlV. It does not replace an on-site survey.

Quantity take-off under VOB: verifiable measures, reference rules, and the role of the BoQ in tendering.

Structure of a VOB bill of quantities: item numbers, headings, line items, and link to quantity take-off.