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B1P Group's as-built BIM is the model of the asset as built: updated during the works with variations and installed products, checked at completion against the verification survey of the appointed surveyor, completed with the data the requirements specify for operation and handed over in native format and IFC. For contractors who have to deliver it and clients who have to receive it.
The as-built model represents the asset as it was actually built, not as it was designed: verified geometry, the products and components actually installed, identification and maintenance data. In UNI 11337-4 it corresponds to level of development LOD F, which describes the object as built and verified on site.
It is the deliverable that closes a BIM construction project and the starting point for operating the asset; a poorly made as-built model is a model the operator will not use.
During the works, not afterwards: the construction model is updated with every variation and every installation, so at completion only the check remains. A contractor who reaches handover with the design model and a paper file of variations has to rebuild everything, with costs and time the contract does not usually allow for.
If the construction model has not been kept up to date, the as-built model is built through BIM modelling from survey data of the finished asset and from the suppliers' documentation; it is the longer route, but it is the one that delivers a reliable model.
As projects funded by the PNRR (Italy's National Recovery and Resilience Plan) close, many contracting authorities require the as-built model for testing and acceptance and for the handover of the asset, often as a condition of the final interim valuation. The contractor must hand over a model that matches the asset as built and contains the data required by the exchange information requirements, even when the model was not updated during the works.
In that case we work on the laser scanning survey of the visible parts, carried out by the appointed surveyor, and on the site records for the hidden ones, and we deliver the model, drawings, maintenance data and a design versus as-built comparison report. The same applies to linear infrastructure in operation, such as tram and railway lines, where track, poles, cable ducts and underground utilities matter most.
With the verification survey at completion, carried out by the appointed surveyor by laser scanning in the building services and structural areas, and with targeted site visits elsewhere: we compare the point cloud with the model and correct the differences beyond tolerance. The comparison report states tolerances, areas checked and remaining deviations.
The level of checking is agreed with the client in the BIM execution plan: not every part of the asset needs the same accuracy.
The data the operator will use: component identification (manufacturer, model, serial number where needed), location (room, system, zone), maintenance data (frequencies, documents), link to the technical documentation. They are set by the exchange information requirements; where the requirements are silent, we propose a minimum set consistent with ISO 19650-3.
An as-built model with too much data nobody asked for is costly and does not get maintained; with too little it is no use. The right set is decided with whoever will operate the asset, before handover: in the as-built model of a data centre, for example, racks, switchboards, UPS units and cooling units with the data the client's management system needs to read.
The two routes to an as-built model, depending on how the works were run.
| Situation | Method | What you need | Time |
|---|---|---|---|
| Construction model updated during the works | Final check against the verification survey and completion of the data | Construction model, variation register, suppliers' documentation | Weeks |
| Design model not updated | BIM modelling from the survey of the finished asset and rebuilding of the model where it has changed | Design model, survey, suppliers' documentation | From weeks to months, depending on the size of the asset |
| No model | BIM modelling from a full survey and as-built modelling | Survey, available drawings, documentation | Months, depending on the size of the asset |
It is when the exchange information requirements call for it, and they almost always do on projects that use BIM in the construction phase; handover of the as-built model is often a condition for the final interim valuation. It is worth checking the requirements before you tender.
It depends on the size of the asset, the disciplines required and how well the works are documented. After a site visit and a review of the exchange information requirements we give times and costs; modelling from the survey data can proceed in sections, so the first parts are handed over while the others are still in progress.
The as-built model describes the asset as built at handover; the asset information model is the as-built model maintained over time, with up-to-date operation and maintenance data. The second grows out of the first, if the first contains the right data.
No: where the construction model has been kept up to date, targeted site visits are enough; laser scanning is needed in dense building services areas, on structures and where the site records are unreliable.
Yes, together with the native files, with the property sets the requirements specify for operation. IFC is the format the asset operator will still be able to open in ten years' time.
Tell us how the works were run: we will propose the shortest route to a reliable as-built model.
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