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Construction

BIM for construction and as-built

Buildability, time in 4D, quantities and cost in 5D, progress and interim valuations on the model, as-built for handover: the BIM that builders need.
At a glance

B1P Group's BIM for construction turns the design model into a construction model for contractors and works supervisors: buildability checks, a programme linked to the model (4D), quantities and progress (5D), interim valuations derived from the model, management of variations and an as-built model ready for handover to the client, in line with the exchange information requirements and UNI 11337.

Definition

What is BIM for construction?

It is the use of the information model during construction: the design model is completed with site information (phases, work packages, suppliers, actual products), linked to the programme and the bill of quantities, and updated with progress and variations until it becomes the model of the asset as built. The contractor uses it to plan, measure and report; the works supervisor uses it to check.

It does not replace the site, but it removes the part of the work that is done twice today: quantities recalculated, drawings updated by hand, interim valuations rebuilt from spreadsheets.

Deliverables
Construction model with phases and work packages, 4D simulation, quantity take-off from the model, progress dashboard, interim valuations derived from the model, variations register, as-built model
Standards
UNI 11337-4 (levels of development for construction), the project's exchange information requirements and BIM execution plan, ISO 19650-2, works supervision practice on the model
Tools
Autodesk Forma for the site, Navisworks for 4D and quantities, Revit for model updates, in-house automation for progress dashboards
BIM for construction and as-built

What changes for the contractor with the model on site?

Clashes are found in the office, quantities come from the model and are the same for the bill of quantities, procurement and accounting, and the programme can be seen on the model and discussed with the works supervisor on a shared basis. Variations are modelled before they are carried out and quantified in hours, not weeks.

The contractor does not have to model everything itself: B1P Group receives the design model, brings it to construction level in the parts that are needed and keeps it up to date with site data, working alongside the site manager and the technical office.

BIM for construction and as-built

How does works supervision use the model?

The works supervisor uses the model to check that what has been built matches the design, to verify interim valuations and to manage variations on a measurable basis. In public contracts the construction phase is already covered by Annex I.9 to Legislative Decree 36/2023, which concerns both the design and the construction of the asset: site rules and deliverables are written into the project's exchange information requirements and BIM execution plan.

On public projects the works supervisor receives periodic deliveries from the contractor through the common data environment: updated model, progress, change register. B1P Group supports one party or the other, never both on the same project.

BIM for construction and as-built

How do you get to the as-built model?

By updating the model during the works, not at the end: every variation, every actual product installed, every change to service routes goes into the model as it happens. At the end of the works a verification survey (including laser scanning) checks that the model matches the asset, and the model becomes the as-built model to hand over to the client, with the data for operation.

Delivery of the as-built model is often a contractual condition for the final interim valuation: it is best to set it up in the BIM execution plan at the start of the project.

Model uses

What is the construction model used for?

Typical model uses during construction, with the corresponding deliverable. They are chosen in the BIM execution plan according to the contract.

UseWhat you getHandover
BuildabilityRemaining clashes, assembly sequences, space checks for plant and vehiclesBuildability report, updated model
4DProgramme linked to the objects, phase simulation, planned versus actual comparison4D simulation, schedule by work package
5DQuantities from the model for the bill of quantities, procurement and accounting, financial progressQuantity take-off from the model, progress dashboard
Interim valuations and variationsInterim valuations derived from the model, variations modelled and quantifiedInterim valuations on the model, variations register
As-built modelModel of the asset as built, verified by surveyAs-built model, IFC, data for operation
Related services

What does it combine with?

Frequently asked questions

Frequently asked questions about BIM on site

Does the contractor need an in-house BIM office?

No. You need a contact on site who knows the project; B1P Group handles the modelling, updates and dashboards, with deliveries through the common data environment. Contractors who want to build their own capability can do so through BIM implementation and training.

Can interim valuations really be produced from the model?

Yes, if the model is at construction level and the quantities are linked to the items in the bill of quantities: progress is recorded on the objects and the interim valuation is extracted with the same quantities as the contract. On hospital and infrastructure projects, this is how we work.

What is needed to start when work on site is already under way?

The design model, the bill of quantities, the programme and the exchange information requirements. If the design model does not exist or cannot be used, we rebuild it for the parts the site needs.

Is the construction model valid for works supervision on public contracts?

Yes, if the exchange information requirements provide for it: periodic deliveries through the common data environment, comparison with the design and reporting are set in the requirements and in the BIM execution plan, which states what is delivered and when. The Ministry's guidance on the construction phase will come with the second document, expected in 2026.

Contact

Do you have a construction project to bring onto the model?

Send us the design, bill of quantities and programme: we will tell you which model uses are worthwhile and what we will deliver.

Request a meeting B1P Group's BIM consultancy