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HBIM·Reference specification

HBIM Level of Detail (LoD) Specification Sheet

Agree, in writing and element by element, how detailed a Heritage BIM model will be — before modelling starts. "An HBIM model" means very different things at different levels of detail, at very different costs. Use the reference to align on terms, then fill the specification so the client and modeller agree on exactly what each element will contain.

Free to use. Print, or use Print → Save as PDF to download and fill.

How to use this sheet

Level of detail is where HBIM projects most often go over budget or under-deliver, because the client pictured photo-real carving while the quote assumed simplified masses. Detail is not free: modelling a temple's ornament to survey accuracy can cost many times more than a clean structural model. This sheet forces that conversation to happen up front, per element, not after delivery.

Fill the specification table with the client. For each element class, agree the target LOD, the geometric tolerance, and the source data it will be built from. Record what is deliberately excluded — that is as important as what is included.

Level of detail — reference

Indicative LOD stages as applied to heritage elements
LODGeometryTypical heritage use
LOD 100Massing / placeholderEarly studies, context massing
LOD 200Generic elements, approximate sizeFeasibility, area schedules
LOD 300Accurate size and position, standard profilesConservation drawings, most HBIM
LOD 350Interfaces and connections modelledRepair detailing, clash checking
LOD 400Fabrication-level detailReplication of joinery, specific repairs
LOD 500As-built, verified against surveyDigital record, asset management

Element-by-element specification

Agree a target for each element class
Element classTarget LODGeometric toleranceSource dataIncluded data (LOI)

Exclusions and sign-off

Elements deliberately excluded from the model
Simplifications agreede.g. ornament represented as texture, not geometry
Deliverable formats (RVT, IFC, drawings)
Client — name, signature, date
Modeller — name, signature, date