German VOB Standard Calculation Rules for Buildingbook

Learn the rules used by the German VOB Standard to calculate quantities for building parts.

The VOB Standard requires some special rules for calculating quantities. In addition to real quantities for joins, interactions, layers, parts, and assemblies, the VOB specifies rules for ignoring openings in walls.

Calculation rules differ according to trade, especially regarding subtraction of openings (sub-areas). For example, the VOB defines the following opening measurements systems:

• Masonry, concrete, and reinforced concrete works: openings less than or equal to 2.5m² are ignored.
• Carpenter, wood construction, upholsterer, curtain wall, sealing, plumber, roof cladding and sealing: openings less than or equal to 2.5m² are ignored.
• Tiles and plates, screed, flooring, wooden planks, asphalt, parquet works: openings less than or equal to 0.1m² are ignored.
• Plaster and stucco, paint and varnish work: openings, recesses, and niches, less than or equal to 2.5m² are ignored.
• Natural stone works: recesses and openings less than or equal to 0.1m² are ignored.

These rules were defined to simplify the process of hand calculation, such as ignoring smaller openings or applying basic mathematical methods for calculating complex building parts. Because a CAD system provides precise quantity calculations, the VOB rules can complicate the process, as they represent arbitrary rules that are only applied in specific cases that are not always clearly defined. For this reason, a CAD-based quantity calculation can't always be performed by the system and will require user input.

The Subelements dialog contains the following more detailed information:

• The Element column lists the subelements that belong to the calculated quantity.
• Columns display area, volume, length, height, and thickness for each element.
• Area and Volume columns have associated Area VOB and Volume VOB columns with automatically set drop-down Yes and No options.
  • Yes - according to the current VOB settings, this opening is calculated.
  • No - this opening is ignored (not calculated) because of the current VOB settings.

The Yes/No options can also be manually set. If you want to apply global changes, you should adjust the VOB Standard Calculation Rules and re-calculate.