BOQ, Specification and Quantification of Demolition

Asad Ali

Mon, 24 Aug 2026

Demolition work must be understood through three connected contract documents: the Bill of Quantities (BOQ), the specification, and the drawings. Together, these documents define what is to be removed, the conditions under which the work must be carried out, and the method used to quantify it.

This article explains a road-demolition example in which the BOQ includes existing structures and road-related assets. It also demonstrates a simple approach to measuring a Jersey barrier in cubic metres from a drawing section and recording the calculation in a take-off sheet.

1. The role of the BOQ, specification and drawings

A BOQ quantity may be approximate at tender stage. Under a remeasurement arrangement, quantities are to be verified against actual site conditions and updated according to the work executed on site.

2. Reading a demolition BOQ item

The example refers to a BOQ section presented as 2.01, with roads identified under Bill 2. The demolition description is broadly stated as:

Demolition or dismantling and removal of all existing structures.

“Existing structures” are structures, surfaces or assets already present before the new work is undertaken. For example, an existing building may need to be demolished before a new building is constructed. In a road project, the term can include the following:

• Foundations;
• Manholes;
• Underground utilities;
• Asphalt pavement and associated layers;
• Curbs;
• Drainage structures;
• Lighting fixtures;
• Unsuitable soil and materials.

The relevant contract drawings identify the locations and areas requiring demolition. Drawings may use colours, hatching or legends to distinguish areas to be removed, modified or reconstructed.

Contractor responsibility

The BOQ notes that the contractor is responsible for verifying and quantifying all items from actual site conditions. From a quantity-surveying perspective, this means the contractor’s quantity surveyor should not rely solely on an approximate BOQ quantity where site verification is required.

The item rate is to be distributed across the relevant items and sections. Before starting demolition, the contractor should understand the notes, drawing references, specification requirements and inclusions within the rate.

Example of included demolition-related work

A sub-item described as 1.1 includes existing road demolition work together with temporary structures and falsework. The transcript identifies the following associated activities and assets:

• Traffic control;
• Temporary utilities;
• Relocation of services;
• Protection in place of existing utilities;
• Existing bridge deck, abutments, foundations and related structures;
• Miscellaneous concrete elements, including approach slabs over a freeway;
• Removal and disposal of debris and materials to an approved dump site.

These inclusions are important because the measured demolition item and its unit rate may be intended to cover more than breaking and removing a visible structure.

Addenda and queries

The BOQ reference AD4 Q22 is explained as Addendum No. 4 and Query 22. This indicates that the content was added or clarified after the initial BOQ issue and became part of the contract documentation. In the example, the clarification relates to road works involving bridge elements, abutments and approach slabs.

Unit rate and amount

The stated unit is cubic metre, so the measured quantity is volume. The stated unit rate is 25.53 per cubic metre. The amount is obtained by multiplying the verified quantity by the unit rate.

Where an item is measured in cubic metres, the measurement requires three-dimensional information. In simple terms:

Volume = cross-sectional area × length

3. Specification requirements for cutting, patching and demolition

The specification section discussed is titled Cutting and Patching. While the complete specification should always be read, the highlighted requirements establish an important control process before demolition or cutting begins.

Inspection before work

The contractor must inspect existing project conditions, including elements that may be damaged or moved during cutting and patching. This inspection is necessary to understand the condition of nearby structures, services and finishes before work starts.

The demolition method should prevent damage to other work and provide a suitable surface for subsequent repairs or installations. Work that has been cut or removed must be restored by installing new products so that the completed work complies with the contract documents.

Written request in advance

The contractor is required to submit a written request to the owner 10 days in advance of carrying out cutting that affects:

• The work of the owner or any separate contractor;
• The structural value or integrity of any project element;
• The integrity or effectiveness of weather-exposed or moisture-resistant elements.

This process allows the owner to inspect the proposed work, assess potential risks and decide whether approval should be granted. Starting work without following the required approval process may expose the contractor to responsibility for damage and may affect entitlement to payment.

Information to include in the request

The written request should clearly identify the proposed activity and its effects. The transcript identifies the following required information:

• Identification of the project and the specific area or surface affected;
• Description of the affected work;
• Time required for cutting and excavation;
• Effect on the owner’s work;
• Description of the proposed work;
• Scope of cutting, patching and excavation;
• Trades that will execute the work;
• Products proposed for use;
• Extent of refinishing required;
• Written permission from any separate contractor whose work will be affected.

For the quantity surveyor, these requirements are relevant because they define whether the demolition is authorised, what work is included, and whether the contractor has complied with the conditions supporting valuation and payment.

4. Understanding demolition drawings

The drawing used in the example is described as an IFC drawing, meaning Issued for Construction. Before measuring from any drawing, first read the drawing title, notes, key plan, location plan and legends.

Drawing information to check

• Drawing title: establishes the project and scope represented by the drawing.
• Key plan: shows where the drawing area is located within the wider project.
• Location plan: assists in identifying the physical location of the works.
• Legends: explain colours, line types, symbols and hatching. A quantity surveyor should request the legend if it is missing.
• Sections and elevations: provide vertical dimensions or profiles needed to convert plan information into quantities.

The example drawing title is transcribed as a layout for reconstruction of a road in an air base at a location associated with “tunnel 3”. The exact location wording should be checked against the original drawing title.

Levels and road-profile information

The legend identifies an existing ground level using a dotted blue line and a proposed elevation representing the required finished level. It also refers to vertical-curve information, including:

• End of vertical curve station;
• End of vertical curve elevation;
• Beginning of vertical curve elevation.

Although such information is related to surveying and road geometry, it can be important to a quantity surveyor where excavation, filling, pavement removal or reconstruction quantities depend on changing levels.

Interpreting coloured work areas

The drawing legend in the example distinguishes different types of work. These include:

• 70 mm thick asphalt milling and resurfacing: the existing road surface is removed to the stated depth and resurfaced.
• Road reconstruction about tunnel 3C: shown in red, indicating new road construction in the marked area.
• Walkway and median: pedestrian and road-separation elements.
• Planter box: an existing feature that may require demolition.
• Shrubs: stated as 60 numbers.

Colours alone do not provide a quantity. They identify the work extent; dimensions, levels, sections and the relevant BOQ item determine how the work is measured.

5. Quantifying a Jersey barrier in cubic metres

The worked example demonstrates how to measure the demolition volume of an existing Jersey barrier using a longitudinal station range and a cross-section profile.

Step 1: Identify the station limits

The Jersey barrier runs from station 0+040 to station 0+050. The length is therefore:

0+050 − 0+040 = 10 m

Step 2: Obtain the cross-sectional area

The barrier cross-section is traced in AutoCAD using a closed polyline. The PL command is used to draw around the outline by snapping to the relevant corners. Once the polyline is selected, the Properties palette displays its area.

The area used in the example is 0.388 m². This is the cross-sectional area, not a width.

Step 3: Calculate the volume

Multiply the cross-sectional area by the measured length:

0.388 m² × 10 m = 3.88 m³

The result is the demolition volume for that example barrier length. The presenter notes that this is a demonstration of the method and not necessarily a final site quantity.

6. Recording the take-off in Excel

A clear take-off sheet allows another person to trace the quantity back to the source drawing and verify the calculation. The example entry should include:

The cross-section used to derive the area should be clearly identified, for example with arrows or a note. This helps the checker understand that the value is an area taken from the barrier profile and that the volume is calculated by multiplying it by the station length.

The same process can then be repeated for subsequent station ranges, such as 0+050 to 0+060 and 0+060 to 0+070, wherever demolition is indicated. Each calculation should be recorded separately before the quantities are totalled.

7. Practical quantity-surveying checks

1. Confirm the exact BOQ description, unit and rate before measuring.
2. Read all BOQ notes, addenda and query responses applicable to the item.
3. Check the drawing revision, title, legend and reference number.
4. Verify whether the quantity is based on plan area, cross-sectional area, length, volume or number.
5. Use sections and elevations where a cubic-metre item requires depth or profile information.
6. Record stations, dimensions, drawing references and formulae so that the take-off is auditable.
7. Check site conditions where the contract requires verification of actual quantities.
8. Ensure demolition approvals, inspections and protection requirements in the specification have been followed.

Accurate demolition measurement is not only an arithmetic exercise. A reliable quantity depends on correctly linking the BOQ item, specification obligations and drawing information, then presenting the take-off in a transparent and checkable format.