Accurate information is essential during construction preplanning. Contractors need to understand project scope, quantities, materials, trade requirements, and potential coordination challenges before committing resources to the job.

Traditional estimating workflows often rely heavily on 2D drawings and manual measurements. While these methods remain important, BIM modelling introduces another source of structured project information that can support estimating and preconstruction activities.

BIM modelling and quantity extraction can help contractors connect the visual representation of a building with measurable project information, while coordinated models can also support constructability and clash reviews.

EstimatesPro provides BIM modelling services that include coordinated models, clash detection reporting, coordinated views and sections, exports, and model-based quantity extraction.

What Is BIM-Based Quantity Extraction?

BIM-based quantity extraction involves obtaining measurable information from elements represented within a digital building model.

Depending on the model scope, quantities may relate to elements such as:

• Walls

• Doors

• Windows

• Floors

• Structural components

• Ductwork

• Pipes

• Equipment

• Electrical components

• Finishes

Instead of measuring every relevant element manually from separate drawings, estimators can use model information as part of the quantity workflow.

Research has also explored BIM-based automated quantity takeoff as a way to systematize the extraction of quantities across different work areas and disciplines.

BIM and Traditional Estimating

BIM does not necessarily replace traditional estimating.

In many projects, estimators still need to review drawings, specifications, schedules, and other documents.

Instead, BIM can become an additional source of information.

A practical workflow may involve:

Drawings + Specifications + BIM Model + Estimator Review = More Informed Quantity Analysis

The model can provide a visual and structured representation, while the estimator validates the information against project documentation and scope requirements.

Why Quantity Extraction Matters

Quantity information supports several stages of construction planning.

Accurate quantities can help with:

• Preliminary cost planning

• Material procurement

• Bid preparation

• Trade comparisons

• Budget development

• Scope review

• Resource planning

Construction technology platforms increasingly connect BIM model quantities with estimating and preconstruction workflows. Autodesk, for example, describes model-based quantification as a way to access quantities from 3D models for estimating and bidding.

BIM for Faster Preconstruction Analysis

Preconstruction teams often need to review large amounts of information within limited timeframes.

A BIM model can provide a three-dimensional representation that makes it easier to understand the project's geometry and scope.

Instead of viewing a wall only as a line on a floor plan, teams can examine it within the context of the building.

This can help when reviewing complex areas, large buildings, and projects involving multiple trades.

BIM Modelling and Constructability Review

Constructability is another area where BIM can provide value.

A project may appear technically correct in individual drawings while still presenting practical challenges when all building systems are considered together.

A coordinated model allows teams to examine how components interact.

For example:

• Can equipment be installed in the available space?

• Is there enough clearance around mechanical equipment?

• Can ductwork pass through the proposed route?

• Are service penetrations properly coordinated?

• Do structural elements interfere with MEP systems?

• Is there sufficient access for maintenance?

These questions can be explored before the corresponding work reaches the field.

Identify Problems Before They Affect the Budget

A coordination problem can have financial consequences when discovered late.

Suppose a contractor has already priced a particular installation approach, but later discovers that multiple services cannot occupy the proposed space.

The team may then need to consider redesign, additional labor, material changes, or schedule impacts.

BIM coordination can help expose spatial conflicts earlier.

Clash detection and coordination are widely used to identify conflicts between architectural, structural, and MEP systems before construction.

This makes BIM useful not only for design coordination but also for preconstruction risk review.

BIM for Bid Preparation

Contractors often need to prepare competitive bids while managing large amounts of project information.

A BIM model can provide an additional method for reviewing the scope.

Estimators can potentially use model information to:

• Validate quantities

• Review building components

• Identify scope areas

• Understand project complexity

• Compare model information with drawings

• Investigate unusual building conditions

Model-based quantity workflows are particularly useful when the BIM model is sufficiently developed and aligned with the estimating purpose.

BIM Quantity Takeoff for Different Trades

Different construction trades can use BIM information in different ways.

Concrete

Structural models can provide information about slabs, beams, columns, foundations, and other structural elements.

Framing

Wall and framing information can support material planning and scope review.

Drywall

Modelled wall areas can help support surface-area calculations when the model contains the necessary information.

Flooring

Floor elements and room information can assist with area-based quantity analysis.

MEP

Mechanical, electrical, and plumbing models can provide information about equipment, piping, ductwork, and other systems.

The exact quantities available depend on the quality, completeness, and development of the model.

The Importance of Model Quality

A BIM model is only useful for quantity extraction when it contains appropriate information.

Estimators should not assume that every model automatically contains everything required for a complete estimate.

Before using model quantities, teams should confirm:

• Model scope

• Level of development

• Included disciplines

• Element completeness

• Measurement requirements

• Project specifications

• Exclusions

• Required estimating standards

This is why BIM modelling should begin with a clearly defined purpose.

BIM Coordination and Quantity Extraction Together

One advantage of integrating coordination and quantity workflows is that the same digital model can support multiple project activities.

For example, a contractor may use the model to identify an MEP clash and also review the associated components for quantity purposes.

An integrated workflow can connect:

Model Development → Coordination → Clash Detection → Model Revision → Quantity Extraction → Estimating

This creates a more connected preconstruction process.

Industry workflows increasingly combine model coordination with quantification and estimating to help contractors move from design information toward actionable construction data.

BIM for General Contractors

General contractors can use BIM models as a coordination and information resource throughout preconstruction.

The model can help teams communicate with:

• Architects

• Engineers

• Estimators

• Project managers

• Superintendents

• Subcontractors

• Owners

Instead of relying solely on separate 2D documents, stakeholders can reference a shared three-dimensional representation of the project.

BIM for Subcontractors

Subcontractors can also benefit from detailed model information.

An MEP subcontractor, for example, may use the model to understand system routing and identify coordination requirements before fabrication or installation.

Likewise, structural, framing, drywall, and other trades can use model information to better understand their scope and interfaces with other systems.

Choosing the Right BIM Modelling Scope

Not every project requires the same BIM deliverables.

Before starting a BIM modelling project, define:

Project Purpose

Is the model intended for visualization, coordination, quantity extraction, installation planning, or several purposes?

Disciplines

Will the model include architecture, structure, MEP, or specific trades?

Level of Development

How detailed does the model need to be?

Deliverables

Will the project require a coordinated model, clash reports, views, sections, exports, or quantity information?

Software and File Formats

The required software environment and exchange formats should also be established before modelling begins.

How EstimatesPro's BIM Modelling Service Can Fit the Workflow

EstimatesPro's BIM modelling service is designed around converting drawings and specifications into coordinated 3D models and supporting construction workflows. The service includes BIM modelling, trade coordination, clash detection reporting, coordinated views and sections, exports, and model-based quantity extraction.

This type of workflow can be particularly useful for contractors, subcontractors, estimators, and design teams that need more structured information from their project documentation.

Final Thoughts

BIM modelling can support much more than three-dimensional visualization.

For construction teams, a well-developed model can contribute to quantity extraction, estimating, bid preparation, constructability review, clash detection, and trade coordination.

The key is to define the model's purpose before development begins and ensure that the model contains the level of information required for the intended workflow.

When BIM modelling, coordination, and quantity analysis are brought together, contractors can gain a clearer understanding of project scope and potential construction challenges before work reaches the site.