How to Read and Understand a BOQ Before Signing a Construction Contract

You are about to sign a construction contract worth millions of rupees. The contractor hands you a document with hundreds of line items, measurements in square metres and cubic metres, and numbers that all look reasonable. You sign it, construction begins, and three months later you are paying for "extras" you thought were included.

This happens to homeowners across Matale, Kandy, Kurunegala and every other town in Sri Lanka. The document you signed without fully understanding was a Bill of Quantities (BOQ) — and not knowing how to read it is one of the most common mistakes when building a house.

This guide explains exactly what a BOQ is, what every section means, how to spot hidden costs, and how to compare quotes from different contractors so you get the best deal without surprises.

What Is a BOQ (Bill of Quantities)?

A BOQ is a detailed document that lists every material, labour task, and work item needed to build your house from foundation to finishing. Think of it as the complete shopping list for your entire project.

Unlike a rough estimate, a BOQ breaks everything into individual line items. Each line tells you:

• Item description — What work is being done or what material is used
• Unit of measurement — How it is measured (m², m³, m, kg, or number of items)
• Quantity — How much is needed
• Unit rate — Cost per unit (includes material + labour)
• Amount — Total cost for that item (quantity × unit rate)

BOQ vs Estimate: What Is the Difference?

Many homeowners confuse a BOQ with an estimate. They are related but different:

In simple terms: Cost Estimate = BOQ + Equipment Costs + Overhead + Profit + Contingency. The BOQ is one component that feeds into the full estimate.

Use our construction cost calculator to get a rough estimate, then request a detailed BOQ from your contractor for the exact figures.

The 12 Sections of a Typical House BOQ

A complete BOQ for a house in Sri Lanka is organised into sections following SLS 573:1999 (the Sri Lanka Standard for measurement of building works). Here is what each section covers:

1. Preliminaries

Site setup costs before actual construction begins. Includes temporary facilities, site office, safety equipment, insurance, and waste removal. Many contractors hide these costs or add them later as "extras" — make sure your BOQ includes them.

2. Excavation and Earthwork

Measured in cubic metres (m³). Covers site clearing, soil excavation for foundations, earth filling, compaction, and disposal of excess soil. The depth and type of soil significantly affect this cost — a soil test helps get accurate quantities.

3. Foundation (Substructure)

Everything below ground level: footings, foundation walls, raft or strip foundations, damp-proof course (DPC), and sub-floor concrete. This section should specify the concrete grade (e.g., Grade 20 or Grade 25), reinforcement steel sizes, and cement brand.

4. Superstructure (Columns, Beams, Slabs)

The structural skeleton above ground: columns, beams, floor slabs, and roof slab. Measured in cubic metres for concrete and kilograms for steel reinforcement. This is usually the most expensive section. Check that steel quantities match the structural drawings.

5. Masonry (Walls)

Brick or block walls, measured in square metres (m²). Should specify wall thickness (4.5", 9", or 14"), block type (solid or hollow), and mortar mix ratio. Different wall types have very different costs.

6. Roofing

Roof structure (timber or steel trusses), roof covering (clay tiles, Calicut tiles, metal sheets), gutters, downpipes, and fascia boards. Should specify the exact roofing material brand and gauge for metal sheets.

7. Carpentry and Joinery

Doors, windows, frames, built-in cupboards, and timber work. Each door and window should be listed individually with dimensions, material (teak, mahogany, aluminium, uPVC), and hardware specifications.

8. Plumbing and Sanitary

Water supply pipes, drainage pipes, toilet fittings, sinks, taps, water heater, and septic tank. Should specify pipe material (PVC, CPVC, PPR), diameter, and fixture brands. A vague "plumbing work — lump sum" is a red flag.

9. Electrical

Wiring, conduits, switches, sockets, distribution board, circuit breakers, light fittings, and CEB connection. Should list the number of points per room, wire gauge, and brand of switches. This is one of the most commonly under-specified sections.

10. Plastering and Rendering

Internal and external wall plastering, measured in square metres. Should specify plaster thickness (usually 12mm internal, 20mm external) and mix ratio. Some contractors use thinner plaster to save costs — check this.

11. Finishing Work

Floor tiling, wall tiling, painting (interior and exterior), ceiling work, and decorative elements. This section often has the most room for cost variation. A "finishing work" lump sum tells you nothing — demand itemized tile brands, paint brands, and number of coats.

12. External Work

Driveway, boundary wall, gate, landscaping, and drainage outside the house. This is often excluded from the main BOQ and quoted separately. Ask specifically if external work is included.

How to Read Each Line Item

Let us look at real BOQ line items and understand what they mean:

What to check for each line:

• Description — Is it specific enough? "Concrete for columns" is vague. "Reinforced concrete Grade 25 for columns 225mm × 225mm" is specific.
• Unit — Does the measurement make sense? Concrete should be in m³, walls in m², steel in kg, doors in "no" (number).
• Quantity — Does it match your house plans? A 1,500 sq ft house should not have 500 m² of walls.
• Rate — Is the unit rate reasonable for current market prices? Compare with other quotes.

Provisional Sums and Prime Cost: Watch Out

Two terms in a BOQ that should raise your attention:

Provisional Sums

A provisional sum is an allowance for work that cannot be fully defined at the time the BOQ is prepared. For example, "Provisional sum for water supply connection from main road — Rs. 150,000."

This is normal for items like utility connections where the exact cost depends on distance or conditions. However, large provisional sums for work that could be defined are a red flag. If your contractor puts "Finishing work — Provisional sum Rs. 2,000,000," that tells you nothing about tile quality, paint brand, or what you are actually getting.

Prime Cost (PC) Sums

A prime cost sum is an allowance for materials or items to be selected later by the homeowner. For example, "PC sum for sanitary fittings — Rs. 300,000." You choose the actual brands and models within that budget.

7 Common Tricks Contractors Hide in a BOQ

After reviewing hundreds of BOQs from homeowners across Dambulla, Akurana, and Mawanella, here are the tricks we see most often:

1. Vague Descriptions

"Tiling work for ground floor" tells you nothing. What size tiles? What brand? Porcelain or ceramic? A Rs. 150/sq ft tile and a Rs. 450/sq ft tile will produce very different results. Always demand brand name, size, and quality grade in the description.

2. Missing Items

The BOQ looks complete and the total looks reasonable. But after construction starts, the contractor says "electrical work was not included in the BOQ" and presents a separate bill. Always cross-check against all 12 sections listed above.

3. Underestimated Quantities

A contractor quotes 200 m² of plastering when the actual requirement is 350 m². The low total wins the contract, then the "additional" 150 m² is charged at a higher rate. Have an independent Quantity Surveyor verify the quantities.

4. Low-Quality Material Substitution

The BOQ specifies "cement blocks" without mentioning grade. The contractor uses cheap, low-density blocks that cost Rs. 50 each instead of quality blocks at Rs. 85 each. Always specify the minimum acceptable quality standard.

5. Excessive Provisional Sums

Instead of defining exact tile brands, sanitary ware, and electrical fittings, the contractor puts everything under "provisional sums." This means they control the spending and you have no visibility until the bill arrives.

6. Missing Preliminaries

Site clearing, temporary fencing, water supply during construction, and waste disposal are not included. These get charged as "extras" once work starts. A complete BOQ should always include a preliminaries section.

7. Lump Sum Line Items

"Plumbing complete — Rs. 450,000" tells you nothing about pipe material, fixture brands, or water heater specifications. Every lump sum should be broken into individual items with descriptions.

How to Compare BOQs from Different Contractors

Getting three quotes is good advice. But comparing three different BOQs that look nothing alike is the real challenge. Here is how to do it properly:

Step 1: Ensure Same Scope

Give all contractors the same architectural drawings and specifications. If one contractor quotes with finishings and another does not, the comparison is meaningless.

Step 2: Create a Comparison Spreadsheet

List every item from the most detailed BOQ down the left column. Then fill in unit rates from each contractor side by side. This immediately reveals where prices differ.

Step 3: Check for Missing Items

If Contractor A has 180 line items and Contractor B has 95, Contractor B is almost certainly missing things. Those missing items will appear as "extras" later.

Step 4: Compare Unit Rates, Not Just Totals

Contractor A quotes Rs. 12 million and Contractor B quotes Rs. 10 million. But Contractor B has underestimated quantities and excluded external work. After variations, Contractor B may cost Rs. 14 million. Look at each line.

Step 5: Question Big Differences

If one contractor charges Rs. 42,000/m³ for Grade 25 concrete and another charges Rs. 28,000/m³, there is a reason. Either the cheap one is using lower quality, or the expensive one is overcharging. Ask both to justify their rate.

SLS 573: The Sri Lanka Standard That Protects You

SLS 573:1999 is the Standard Method of Measurement of Building Works published by the Sri Lanka Standards Institution. It defines how construction work should be measured and described in a BOQ.

When your BOQ follows SLS 573:

• All measurements use metric units consistently
• Items are grouped into 22 standard work sections
• Descriptions follow a defined format so nothing is vague
• Quantities are measurable and verifiable from drawings

Ask your Quantity Surveyor to prepare the BOQ according to SLS 573:1999. If your contractor hands you a BOQ that does not follow this standard, it may be harder to enforce and harder to compare.

CIDA Registration: Why It Matters for Your BOQ

The Construction Industry Development Authority (CIDA) registers and grades contractors in Sri Lanka based on their financial capability, technical ability, and experience. When your contractor is CIDA registered:

• They are required to follow industry standards including SLS 573
• Their grading matches the project value they can handle
• You have a regulatory body to complain to if things go wrong
• Their qualifications and track record have been verified

Always ask for the contractor's CIDA registration number and grade. You can verify it through the CIDA website or their information centre.

Your BOQ Checklist Before Signing

Before you sign any construction contract, go through this checklist:

1. All 12 sections present — Preliminaries through external work
2. No vague descriptions — Every item specifies material, brand, size, or quality
3. Quantities verified — Cross-checked against your architectural drawings
4. Provisional sums under 15% — Most items should be fully defined
5. No lump sums without breakdown — Every lump sum is itemized
6. Unit rates are reasonable — Compared across at least 3 contractor quotes
7. Payment schedule matches work — Milestone-based, not front-loaded
8. Exclusions clearly listed — You know exactly what is NOT included
9. SLS 573 standard followed — Measurements are consistent and verifiable
10. Contractor is CIDA registered — Verified registration number on file

If your BOQ fails on any of these points, go back to the contractor and ask them to revise it before signing. Read our FAQ page for more answers about the construction process.