Context

From plot to site-coverage ratio, everything outside the building.

External works are often measured separately, in 2D CAD, and disconnected from the BIM model. Cubica extracts utility supply networks (water, gas, electric), storm drainage (trenches, manholes, gullies), paving (pavements, roads, parking), gardens and landscaping (green areas, trees, irrigation) — all to the metre and square metre, with urban ratios (site coverage and impermeable surface) already calculated for the permit.

On your side

What we need

Revit (.rvt) or IFC model with plot boundary, building footprint and ground levels
External networks modelled by system (water, gas, electric, storm drainage)
Paving and circulation identified by typology (rigid, semi-permeable, landscaped, parking)
Green spaces by model region, with typified plant species

On our side

What you receive

Supply networks and drainage to the linear metre, with counts of manholes, gullies and connections
Paving and roads in m², split by typology — ready for subcontractor pricing
Gardens and landscaping: green areas in m², count of trees and shrubs, length of irrigation system
Urban ratios: site coverage and impermeable surface in %, ready for the permit process
Telecoms and irrigation to the linear metre, separated from the other networks — not diluted into "water" or "electrical"
A list of what could not be classified — if a run has no system assigned in the model, it is not silently counted: it is listed in the report for you to decide
Full traceability to the BIM element — every value maps back to the source object
2D/3D drawing (DXF/DWG) of the networks, paving and measured areas — layered and colour-coded by category, with each element's ID, matching directly to the Excel and the model

How we measure

External works begin where the building ends — and that boundary is computed, not drawn by hand.

The classic error here is double counting: a pavement running under the building, an internal pipe ending up in the external networks. Our engine computes the building's real footprint from walls, floors and roofs, and uses it to decide what is inside and what is outside — element by element, clipping whatever straddles the line.

1 · Networks by the Revit system, not by the pipe's name — the system governs; the type name only decides what the system leaves open. Drainage and irrigation take precedence over "water", or an irrigation line would land in the supply network.
2 · Paving from the actual surface — area comes from the element's top face, not its bounding box. A curved pavement or an angled parking bay measure what they are.
3 · Ratios already calculated — site coverage and impermeable surface in %, over the plot area you point us to. With no plot boundary defined we do not invent a percentage: we say it is missing.
4 · A drawing that checks the Excel — each network as a line on its real axis, each tree as a circle, each paving as a surface, all with the element ID on a layer you can switch off. Open the DXF next to the Excel and you see where every number comes from.

Sample deliverable

Networks per metre, paving in m², planning ratios already calculated.

Excerpt from External_Works.xlsx — simplified example. The real file includes additional tabs per zone and system.

Arranjos_Ext.xlsx

Reference project: residential building · 44 units · 7 floors + basement · 2 145 m² plot.

Item	Unit	Quantity
Utility supply networks (underground)
Water supply (Ø 63-110)	m	312
Gas supply (Ø 32-90)	m	148
Electrical (LV buried)	m	220
Networks linear subtotal	m	680
Storm drainage
Drainage trenches	m	184
Manholes	un	12
Gullies	un	8
Connections to public sewer	un	6
Paving and circulation
Pedestrian pavements	m²	287
Access road	m²	412
Surface parking	m²	156
Impermeable areas subtotal	m²	855
Gardens and landscaping
Landscaped zones (lawn + beds)	m²	540
Medium-size trees	un	24
Shrubs and hedges	un	68
Drip irrigation system	m	320
Urban ratios (permit)
Plot area	m²	2 145
Building footprint	m²	740
Site coverage ratio	%	34,5
Impermeable surface ratio	%	74,4

The arithmetic, in the open

Networks: 312 + 148 + 220 = 680 m. Impermeable areas: 287 + 412 + 156 = 855 m². Site coverage: 740 / 2,145 = 34.5 %. Impermeable surface: (740 + 855) / 2,145 = 74.4 %. None of these is typed in — they are live formulas in the Excel itself.

A run with no system assigned in the model is not guessed into one of these rows: it is listed in the report, for you to decide which line item it belongs to.

Every value is auditable back to the source element — filter by system, by zone, by typology. At each design revision it reprocesses with no manual remeasuring.

Difference

Why not by hand, and why not a generic tool

Better than measuring by hand

The boundary between building and site is calculated, not eyeballed.The classic error here is double counting: the pavement that runs under the building, the indoor pipe that ends up in the external networks. The real footprint comes from the model's walls, floors and roofs — anything half in, half out is clipped, not rounded.
Each network is classified by the model's system, not by the pipe's name.Drainage and irrigation take precedence over «water». Without it, an irrigation line lands in the supply network — and reaches the budget priced as a different trade.
A paved area comes from the real surface, not from its bounding box.A curved pavement and an angled parking bay measure what they are. Measured by the rectangle around them, they are overpaid — and the gap grows with every curve in the road.
A run with no system assigned comes out flagged, never allocated by guesswork.It appears in the report, waiting for a decision. Added to the wrong item, nobody notices until the subcontractor arrives on site.

What generic tools do not do

Planning ratios come out already calculated, ready for the application.Site coverage and impermeable area as percentages, over the plot area you give us. With no plot boundary defined we do not invent a percentage: we say it is missing.
Telecoms and irrigation come out separated from the other networks.A generic schedule groups by family and dissolves both into «water» and «electrical». The budget ends up with too many metres in one item and too few in another, and both still balance.
The drawing and the takeoff come out of the same calculation.Each network as a line on its real axis, each tree as a circle, each paved area as a surface — with the element ID on a layer you can switch off. Open the DXF beside the Excel and you see where every row comes from.
The measurement keeps up with design revisions.Change a network's route or a paving boundary and it is reprocessed, without re-measuring by hand what did not change.

What the model does not classify is not guessed. A run with no system assigned, a paved area with no type, or a plot with no boundary defined all come out flagged in the report, for whoever prices the job to decide. On a simple development, with everything classified up front, a careful manual takeoff reaches the same figure. It is on schemes with many networks and many paving types that the difference shows up in the budget.

Every number in this section comes from real measurements and can be substantiated on request. What we have not measured, we do not claim.

Scope

Cubica measures every modelled element and returns the 3D/DXF of everything measured, so each quantity can be checked against its geometric origin. The scope of the measurement is, by definition, the content of the model supplied: elements that were never modelled, or modelled incorrectly upstream, cannot be measured by any extraction method — which is why we report in writing the omissions and inconsistencies we find along the way.

The service is delivered from the model and documentation supplied, without a site visit: we measure what that information represents. Existing conditions it does not represent therefore fall outside the scope — changes made on site, deterioration, concealed elements and pre-existing works. Where a divergence between the model and what is built is identified, we reprocess the measurement on the corrected information.

External Works.