‘The best laid plans of mice and men’ is a famous line from a poem about a mouse whose nest was destroyed by the poet Robert Burns. Men also create designs for their own nests that somehow don’t always work out as planned. Unlike mice, men can adapt design to suit their requirements as construction progresses. Drawings created to correctly record these changes are known as as-built drawings, or as-fitted drawings, or as-installed drawings. As-fitted models can be created from the as-fitted drawings to visualise the changes and actual building details in 3D, using 3D BIM (Building Information Modelling) modelling services.
Always expect change.
Design documentation differs almost always with how buildings are actually built. Disparate skills, technique, materials, change-orders, natural causes and evolving mechanical processes can change direction from the original design intent.
Circumstances on site can result in both major and minor changes. As-fitted drawings are created during construction or when construction is complete to reflect the actual build. A general contractor can mark changes to ‘final construction issue’ drawings on-site, which can be used to create as-fitted drawings. Data can be supported with as-built surveys. As-fitted drawings, also called ‘as constructed’ drawings, can be used for building health and safety or operations and maintenance by the client.
Who updates these drawings, and why are as-fitted models so important?
- They are required to update construction methods.
- Specialist trade contractors must record what has been installed on site, in addition to engineers and architects.
- Records of under-floor cabling in office buildings can be tricky, as tenants cut off and leave in older cables while installing their own systems. Cabling records thus become very important.
- Facilities management teams keep updated record drawings to avoid future surveys of any modifications.
- A BIM as-fitted model must be updated to reflect any design changes and then given to the client so that the facilities management team can continue to update it.
- As-fitted BIM models help identify all changes to the original design and plan construction workflow accordingly.
- The as-fitted BIM models are precise and data-laden and are created after integrating changes all construction stages.
What changes do as-fitted models show?
Different types of architectural documentation, including construction drawings, feasibility plans, demolition plans, permit plans, mechanical plans, electrical plans, space plans, elevations and sections, can be reflected in as-fitted BIM models.
Changes, such as, design changes, field changes, approved and disapproved changes during construction and any minor or major modification to the final project, can be reflected in these models.
As-fitted drawings and models show changes in:
- Component dimensions
- Component geometry
- Component location
- Wall details
- Door and window details
- Electrical details
- Plumbing fixtures.
The plans reflected in as-fitted models include any changes in the following:
- Structural Plans – Structural drawings have different subsets: General Notes, Plans, Elevations, Sections and Details.
- General Notes detail the building design codes and by-laws, material properties (steel or wood grade, concrete strength, etc.), construction requirements (soil compaction, weld procedures, etc.) and design criteria (gravity , seismic and wind loading).
- Structural drawings show the foundation, floor and roof plan of the building, with size and location of structural elements.
- Elevations show the exterior walls, with the height of building floors, roof elevations and structural properties of elements in the walls not seen in plan drawings.
- Sections provide structural element data not seen in plan drawings.
- Detail drawings include information on how to construct or connect structural elements.
- Architectural design plans include floor plan, roof plan, elevations, reflected ceiling plans.
- Building engineering, or MEP, plans include HVAC, electrical, plumbing and fire design plans
An extensive bank of details and documents are included in as-fitted drawings and models, such as:
- Changes in materials, dimensions, locations, installations, fabrications, etc.
- Dates of changes
- Changes resulting from the final inspections
- Unforeseen challenges faced by the contractor and how they were resolved
- Modified shop drawings
As-fitted drawings and models can be generated by physically measuring an existing building with precision lasers, 3D laser scanners and relevant software packages for CAD or BIM documentation. As-fitted models and drawings benefit different stakeholders in different ways, such as follows:
- Landlords and building owners use as-built models and drawings for lease area audits, facility management and asset tracking.
- Architects and engineers use as-builts to familiarise themselves with existing conditions before renovation or retrofit.
- Fabricators and installers need accurate as-built data to fabricate components off site to specifications and identify spatial constraints before installation.
As-built documentation can be developed for older facilities, where any documents are often outdated or missing. The data embedded in as-built models forms a base for building operations and future building plans of new buildings. It is the responsibility of stakeholders to make sure that as-built documents are regularly updated. With reliable BIM MEP services partners on board, project stakeholders can ensure high-quality MEP 3D BIM modelling and as-fitted models are created to last through a building’s lifecycle.
XS CAD has valuable experience providing 3D BIM modelling services and as-built drawings for contractors. Our range of services for structural, architectural and building engineering firms, such as consultants and contractors across the world, include 3D BIM modelling, as-installed drawings, and BIM MEP services. We have proven to be a preferred Revit BIM outsourcing partner, due to the high quality and clash-free 3D models, created by using Revit, AutoCAD, and BIM 360 Design for cloud collaboration.