Estimation and BOQ for interior projects

In short

Estimation is the process of working out, before work starts, how much material, labour and money an interior project will need; the Bill of Quantities (BOQ) is the itemised document that records each item of work, its unit, measured quantity, rate and amount. For interior projects the BOQ is both the pricing instrument (contractors quote against it) and the control document (site measurement, running bills and variations are checked against it). It matters because interiors are sold at a per-square-foot or lump-sum price while being built out of hundreds of separately-rated items — margin is won or lost in measurement rules and rate analysis, not in design. It is examined in B.Des / B.Sc Interior papers on "Estimation, Costing and Specification", in professional practice papers, and tested in almost every placement interview at design-build firms (Livspace, HomeLane, Design Cafe, Sleek, Godrej Interio, Bonito, Pepperfry Studio) and at contracting and PMC firms (Shapoorji, Leighton, CBRE, JLL, Colliers project management).

Explained

Estimate, BOQ and the documents around them

• Estimate - a calculated forecast of cost prepared by or for the client/designer. BOQ - a tabulated list of items (description, unit, quantity, rate, amount) issued for tendering and billing. Quotation - a contractor's priced offer, often against the client's BOQ.
• Preliminary / approximate estimate - plinth-area or carpet-area rate × area, used at concept stage for the client's budget sanction. Accuracy roughly ±15-25%.
• Detailed estimate - every item measured from drawings with rates from rate analysis or a schedule of rates; accuracy within about ±5-10% when drawings are frozen.
• Revised estimate - prepared when the sanctioned estimate is exceeded (commonly beyond about 5%) or scope changes; supplementary estimate - for work added later.
• Schedule of Rates (SOR) - a government or company rate list. CPWD Delhi Schedule of Rates (DSR) with its Analysis of Rates volume is the standard reference for civil and finishing items in India; state PWDs publish their own SORs. Rates are revised periodically with a cost index, so always quote the edition and the index applied.
• Specification - the written quality standard attached to each BOQ item. General specification describes the whole job briefly; detailed specification fixes material, brand/equivalent, workmanship, tolerance and mode of measurement. A rate without a specification is unenforceable - the single commonest dispute in interiors.
• Supporting documents: drawing register, item code list, Abstract of Cost (summary by section), Measurement Book (MB) for recorded site measurements, Running Account (RA) bill, variation/change order register, Preambles (measurement and payment rules), and a BOQ summary with contingencies, overheads, profit and taxes.

How an interior BOQ is structured

• Standard sectional order used in Indian interior tenders:
  1. Preliminaries / general items - site establishment, hoarding, protection, scaffolding, housekeeping, debris removal, insurance, as-built drawings.
  2. Demolition and civil work - dismantling, brick/block partitions, plaster, waterproofing, screed, core cutting.
  3. Partitions, ceilings and dry construction - gypsum/calcium-silicate board partitions, grid and plain false ceilings, bulkheads, access panels.
  4. Joinery / woodwork - wardrobes, kitchen units, storage, panelling, doors and frames, counters.
  5. Finishes - flooring, wall tiling, painting, polish, wallpaper, veneer, glass and mirror, upholstery.
  6. Electrical and lighting, HVAC, plumbing and sanitary, fire detection and suppression, data/AV/security (the MEP package).
  7. Loose furniture, FF&E, soft furnishing, artefacts, plants, signage.
  8. Design fee, PMC fee, statutory approvals, contingency, taxes.
• Each item carries an item code, description with specification reference, unit, quantity, rate, amount. Keep units and codes identical across BOQ, MB and RA bill so billing reconciles automatically.
• BOQ types: *firm/lump-sum* (quantities fixed, risk on contractor), item-rate (measure-and-pay) - most common in interiors, quantities provisional and re-measured on completion, *percentage-rate* (bid as % above/below an SOR), cost-plus (actual cost + agreed fee, used for fast-track fit-outs), and Provisional Sums / NMR (non-measurable items) for work not yet designed.

Units and modes of measurement

• Linear metre / running foot (Rm, Rft) - skirting, beading, handrail, cornice, pelmet, electrical conduit, kitchen platform length.
• Square metre / square foot (sqm, sft) - flooring, tiling, painting, partitions, ceilings, panelling, glass, wallpaper, carcass of joinery by front elevation area.
• Cubic metre (cum) - brickwork, concrete, excavation, filling; also timber in section.
• Number (nos.) - doors, lights, switches, sanitary fixtures, hardware, loose furniture.
• Kilogram / quintal - MS and SS sections, reinforcement, hardware by weight.
• Litre / kg - paint, polish, adhesive when supplied as material.
• Deductions and mode of measurement follow IS 1200 (Method of measurement of building and civil engineering works), which is published in many parts - Part 1 earthwork, Part 11 paving/floor finishes/skirting, Part 12 plastering and pointing, Part 15 painting and polishing, Part 21 woodwork and joinery, Part 14 glazing. Several parts have been revised or amalgamated, so cite the part by subject if unsure of the current edition. Contract preambles may override IS 1200 - the contract prevails.
• Typical rules worth remembering: no deduction for openings up to a stated small area in plaster/painting; painting of panelled doors and grills measured by multiplying factors on the flat area; false ceiling measured on plan area with no deduction for small cut-outs but deduction for large openings; joinery measured either by front elevation area (modular and commercial practice) or by actual developed board area with "cutlist" (carpenter/bespoke practice) - never mix the two in one BOQ.
• Area definitions matter in per-sft pricing: carpet area (usable floor inside walls - defined in RERA, the Real Estate (Regulation and Development) Act, 2016 as net usable floor area excluding external walls, balcony and service shafts, including internal partition walls), built-up area (carpet + wall thickness + balcony), super built-up / saleable area (built-up + proportionate common area). Interior quotes should state which area is used; firms usually price on carpet area.

Rate analysis - building a rate from first principles

• A rate = material + labour + plant/tool + wastage + overheads + profit, worked out per unit of finished work.
• Steps: (1) fix the specification; (2) list materials per unit with coefficients; (3) add wastage; (4) add labour by task-work output (skilled/semi-skilled/helper days per unit); (5) add transport, lift/hoisting, scaffolding, consumables, power; (6) add water charges (about 1% in DSR practice); (7) add contractor's overheads and profit (typically 10-15% in SOR analysis, 15-25% in retail interiors); (8) add taxes separately.
• Typical wastage allowances (verify against the project specification, they are not statutory): plywood and board 5-10% due to cutting, laminate 5-10%, tiles 5% (10% for diagonal laying or small spaces), paint 5%, glass 5-10%, carpet rolls 10-15%, hardwood 10%.
• Labour outputs (indicative task work from DSR-type analysis): a carpenter and helper build roughly 1.5-2.5 sqm of carcass a day; painters cover about 15-25 sqm/day per coat of emulsion; tilers lay about 8-12 sqm/day; gypsum ceiling crews fix about 10-15 sqm/day. Always calibrate to your own site records.
• Labour wages are governed by the Code on Wages, 2019 and the other three Labour Codes, in force from 21 November 2025 (they replaced the Minimum Wages Act, the Factories Act, the Industrial Disputes Act and the BOCW Act). Minimum/floor wages are notified by the Centre and states and are revised periodically - take the current notification for the project state rather than any remembered figure. Site labour welfare, safety and welfare-cess obligations now flow from the Occupational Safety, Health and Working Conditions Code, 2020 and the Social Security Code, 2020; the building and construction workers' cess continues under the Social Security Code.
• Depreciation and hire of machinery (tile cutters, routers, panel saws, scaffolding) is loaded as hire per day ÷ daily output.

Step-by-step: preparing an interior BOQ

1. Freeze drawings - layout, ceiling plan, electrical and plumbing plans, elevations, joinery details with sections, finish schedule.
2. Create the item list section-wise from the drawings, with item codes; write specifications first, descriptions second.
3. Take off quantities - measure systematically (room by room, then service by service), using the centre-line method for continuous partitions/skirting of uniform thickness and the long-wall-short-wall method otherwise; keep a take-off sheet showing No. × L × B × D so the arithmetic is auditable.
4. Apply deductions for openings, cut-outs, pass-throughs as per IS 1200 / preambles.
5. Add wastage and lap/overlap where the item is cut from sheets or rolls.
6. Price it - rate analysis for bespoke items, SOR/market rates for standard items, vendor quotes for proprietary items (hardware, appliances, modular systems, lighting fixtures).
7. Abstract - section totals, then add preliminaries, contingency (typically 3-5% of works; higher in renovation of an occupied space), design and PMC fee, escalation if the programme is long.
8. Add taxes - GST on the works contract/supply, then issue for tender or client approval.
9. Tender comparison - normalise the quotes (same quantities, same inclusions), prepare a comparative statement item-wise, flag abnormally low/high rates and unpriced items.
10. Post-award - joint site measurement into the MB, RA bills by stage, variation orders priced from the BOQ rates for similar items (or by new rate analysis if the item is new), and a final bill with reconciliation statement.

Taxes, compliance and contract commercials

• GST: since 22 September 2025 the slab structure is 5%, 18% and 40% (the 12% and 28% slabs were removed; the 40% rate applies to a notified demerit list). A turnkey interior contract is normally a works contract - a composite supply of service - taxed at the single applicable service rate on the whole contract value, while pure supply of furniture or appliances is taxed as goods. Rates and classifications change with every Council meeting, so confirm the current notification and HSN/SAC before quoting rather than relying on a remembered percentage.
• Input tax credit is generally not available to the recipient on works contract services and on goods/services used for construction of immovable property, except where the recipient is itself supplying works contract service or the item remains movable - the reason loose furniture and civil fit-out are often billed separately. Take a CA's view per project; this is a litigated area.
• TDS: tax deducted at source on payments to contractors is now governed by the Income-tax Act, 2025, in force from 1 April 2026, which renumbered the sections and forms of the 1961 Act (the old section 194C contractor provision). Use the current section numbering and rates from the 2025 Act; rates for contractor payments are commonly 1% for an individual/HUF payee and 2% for others, but verify the notified rate.
• Contract commercials: mobilisation advance, retention (typically 5-10% released on defect-liability expiry), defect liability period (usually 12 months), liquidated damages for delay, price escalation clause, and arbitration/dispute resolution. Public interior tenders follow GFR 2017 procurement rules and the CPWD/PWD contract conditions.
• Professional practice: the Council of Architecture governs the title "architect" and architects' fee scales; interior designers in India are not statutorily registered, and bodies like the Institute of Indian Interior Designers (IIID) publish guidance and model fee ranges. Fire, occupancy and material requirements come from the National Building Code of India 2016 (Part 4 Fire and Life Safety, which governs surface-finish flame spread in interiors) and the local development control regulations.

Key points

• Estimate - pre-construction forecast of cost; BOQ - priced, itemised measurement document used for tendering and billing.
• Approximate estimate - area × per-sft rate at concept stage; detailed estimate - item-wise from frozen drawings.
• Rate analysis - builds a unit rate from material + wastage + labour + plant + overheads + profit, excluding taxes.
• Schedule of Rates - published rate list (CPWD DSR with its Analysis of Rates, state PWD SORs), applied with a cost index.
• IS 1200 - the Indian Standard method of measurement, published in parts by trade; the contract preamble overrides it where they conflict.
• Item-rate contract - quantities are provisional and re-measured; lump-sum - quantities fixed and risk sits with the contractor.
• Units - linear for skirting/beading/conduit, area for flooring/ceiling/partition/joinery front elevation, volume for masonry, number for fixtures.
• Carpet vs built-up vs super built-up - per-sft interior rates must state which; carpet area is the RERA-defined usable area.
• Centre-line method - fastest for continuous walls/partitions of uniform thickness; long-wall-short-wall for varying sections.
• Wastage - 5-10% for boards and laminates, 5% tiles (10% diagonal), 10-15% carpet rolls; must be stated, not hidden in the rate.
• Carcass vs shutter rate - commercial joinery pricing splits the box (per sft of front elevation or developed area) from shutters, hardware and finish.
• Contingency - 3-5% of works cost for unforeseen items; higher for renovation of occupied premises.
• Abstract of cost - section-wise summary leading to the total, then preliminaries, fees, contingency and taxes.
• Variation order - priced from existing BOQ rates for similar items, or by fresh rate analysis for genuinely new items.
• RA bill and MB - measurement book entries signed jointly on site are the basis of interim payment; retention held till defect liability ends.
• GST - 5%/18%/40% slabs since 22 September 2025; turnkey interiors usually a composite works-contract service, loose furniture supplied as goods.
• Labour Codes - the four Codes, in force 21 November 2025, now govern wages, safety and welfare cess on interior sites.
• Specification is part of the rate - "18 mm BWP plywood, IS 710 grade, with 1 mm laminate" is a rate; "wardrobe" is not.

Formulas and examples

Example 1 - Carcass rate analysis for a wardrobe (per sft of front elevation) Specification: 18 mm BWP plywood carcass, 1 mm inner laminate, 8 mm back, edge banding; assume 2.2 sft of board (developed, including shelves and partitions) per 1 sft of front elevation.

• Plywood: 2.2 sft × ₹95/sft = ₹209.00
• Laminate (inner): 2.2 sft × ₹38/sft = ₹83.60
• Back panel + beading + adhesive + screws: ₹30.00
• Material subtotal = 209.00 + 83.60 + 30.00 = ₹322.60
• Wastage at 8% = 322.60 × 0.08 = ₹25.81 → material with wastage = ₹348.41
• Labour: carpenter ₹1,000/day + helper ₹600/day = ₹1,600/day; output 20 sft front elevation/day → ₹80.00/sft
• Tools, power, machine hire: ₹12.00/sft
• Subtotal = 348.41 + 80.00 + 12.00 = ₹440.41
• Overheads + profit at 18% = ₹79.27 → Rate ≈ ₹519.68, say ₹520 per sft of front elevation, excluding shutters, hardware, external finish and GST.
• A 7 ft × 6 ft wardrobe = 42 sft front elevation → carcass amount = 42 × 520 = ₹21,840.

Example 2 - Flooring take-off with wastage and skirting Room 4.2 m × 3.6 m; 600 × 600 mm vitrified tile; 100 mm skirting on all four sides; one 0.9 m wide door opening (no skirting there).

• Floor area = 4.2 × 3.6 = 15.12 sqm
• Wastage 5% → 15.12 × 1.05 = 15.876 sqm; one tile = 0.36 sqm → 15.876 ÷ 0.36 = 44.1 → order 45 tiles
• Perimeter = 2(4.2 + 3.6) = 15.6 m; less door 0.9 m = 14.7 m of skirting; area = 14.7 × 0.1 = 1.47 sqm
• Rate ₹85/sqm laying + tile ₹650/sqm: floor amount = 15.12 × (650 + 85) = 15.12 × 735 = ₹11,113.20
• Skirting at ₹260/Rm = 14.7 × 260 = ₹3,822.00
• Item total = ₹14,935.20 before taxes. (Tiles are ordered on 45 nos. but the client is billed on the 15.12 sqm measured - wastage sits in the rate.)

Example 3 - Painting with a multiplying factor and deductions Wall 10.0 m long × 3.0 m high with one window 1.5 m × 1.2 m and one panelled door 1.0 m × 2.1 m (both painted separately); 2 coats of acrylic emulsion over primer.

• Gross wall area = 10.0 × 3.0 = 30.00 sqm
• Deduct window 1.80 sqm + door 2.10 sqm = 3.90 sqm → net wall = 26.10 sqm
• Panelled door, painted both faces: flat area 2.10 sqm; factor 2.30 for panelled doors measured on one face only including both sides → 2.10 × 2.30 = 4.83 sqm of painting (check the factor table in the applicable IS 1200 part / preamble - factors differ by door type).
• Emulsion: spreading rate 10 sqm/litre/coat → (26.10 × 2) ÷ 10 = 5.22 litre; add 5% wastage = 5.48 litre
• At ₹95/sqm for 2 coats: wall = 26.10 × 95 = ₹2,479.50; door enamel at ₹140/sqm = 4.83 × 140 = ₹676.20.

Example 4 - Carpet-area rate and GST on a 2BHK turnkey fit-out Carpet area 950 sft. Works abstract: joinery ₹9,20,000; false ceiling and painting ₹2,10,000; electrical ₹1,45,000; flooring and tiling ₹1,70,000; loose furniture and soft furnishing ₹1,55,000.

• Works subtotal = 9,20,000 + 2,10,000 + 1,45,000 + 1,70,000 + 1,55,000 = ₹19,00,000
• Contingency 4% = ₹76,000; design fee 8% of works = ₹1,52,000
• Pre-tax total = 19,00,000 + 76,000 + 1,52,000 = ₹21,28,000
• Carpet-area rate (pre-tax) = 21,28,000 ÷ 950 = ₹2,240 per sft
• GST: apply the current notified rate for the works-contract service and for any separately supplied goods; at an illustrative 18% on the whole pre-tax total the tax would be ₹3,83,040 and the contract ₹25,11,040 - confirm the applicable rate and split before issuing a quotation.

Example 5 - Centre-line take-off for gypsum partitions A rectangular cabin block 6.0 m × 4.0 m is partitioned off an open floor by new 100 mm gypsum partitions on three sides (the fourth is an existing wall), height 2.85 m, with a 0.9 m × 2.1 m door.

• Centre-line length = 6.0 + 4.0 + 4.0 = 14.0 m (no corner correction needed for area measured on centre line)
• Gross partition area = 14.0 × 2.85 = 39.90 sqm
• Deduct door = 0.9 × 2.1 = 1.89 sqm → net = 38.01 sqm, measured one side (billed as "partition complete both sides" per the item description)
• At ₹1,350/sqm = 38.01 × 1,350 = ₹51,313.50
• Boards: both faces = 38.01 × 2 = 76.02 sqm; with 10% wastage = 83.62 sqm; one 8 × 4 board = 2.973 sqm → 83.62 ÷ 2.973 = 28.1 → order 29 boards.

Where it is used

• Residential design-build firms - Livspace, HomeLane, Design Cafe, Bonito, Sleek, Pepperfry Studio: per-sft and per-unit modular pricing engines built on exactly these take-off and carcass-rate rules; the "quote engineer" or "design manager" role lives in the BOQ.
• Commercial fit-out contractors and PMCs - office interiors for IT and GCC occupiers (Shapoorji Pallonji, Leighton, Vantage, BW Interiors) and project managers at CBRE, JLL, Colliers, Cushman & Wakefield preparing tender BOQs, comparatives and RA bill certification.
• Hospitality and retail rollouts - hotel guest-room and restaurant/QSR fit-outs where one BOQ is replicated across many outlets, so a ₹20/sft error multiplies across hundreds of units.
• Government and institutional interiors - CPWD, state PWDs, PSU and bank branch interiors tendered on DSR/state-SOR item rates under GFR 2017 procurement rules.
• Job roles - quantity surveyor, estimation engineer, billing engineer, tendering executive, cost consultant, design manager, procurement/vendor-development executive; the QS career path leads to cost consultancy (RICS-aligned practice is common in India).
• Tools on the job - Excel with take-off sheets and structured BOQ templates, Candy/CostX/Primavera in large contracting, and quantity schedules extracted from Revit or CAD-linked models for cross-checking the manual take-off.

Interview questions

• Q: What is the difference between an estimate and a BOQ? A: An estimate is a forecast of total cost, often approximate; a BOQ is an itemised schedule of described, measured work with units, quantities, rates and amounts that is used to tender, award and bill the work.
• Q: Why is the specification written before the description in a BOQ item? A: Because the rate is only defensible if the material, grade, workmanship and finish are fixed; without them the contractor prices the cheapest interpretation and disputes follow at measurement.
• Q: Which standard governs the method of measurement in India? A: IS 1200, published in parts by trade (flooring, painting, woodwork, plastering and so on), unless the contract preamble specifies different rules - in which case the contract prevails.
• Q: How do you price a wardrobe - by front elevation area or by developed board area? A: Either is valid if stated: front-elevation (per sft of width × height) is the commercial and modular convention; developed area with a cutlist is more accurate for bespoke units with heavy internal partitioning. Mixing the two in one BOQ double-counts.
• Q: A client asks why your ₹2,200/sft quote is higher than a competitor's ₹1,600/sft. What do you check? A: The area basis (carpet vs built-up), the inclusion list (loose furniture, appliances, electrical, false ceiling), board and hardware grades, and whether GST and design fee are inside or outside the number - most of the gap is usually scope and area basis, not margin.
• Q: Where does wastage sit - in the quantity or in the rate? A: The client is billed on the measured finished quantity; wastage is loaded into the rate through the material coefficient. Adding it to both inflates the bill twice.
• Q: What is a variation order and how is it priced? A: A written instruction changing the scope; it is priced using the existing BOQ rate for a similar item, a pro-rata derivation from it, or a fresh rate analysis if the item is genuinely new - agreed before execution, not after.
• Q: What is retention and a defect liability period? A: Retention is a percentage (commonly 5-10%) withheld from each bill as security; the defect liability period (usually 12 months from handover) is the window in which the contractor must rectify defects, after which the retention is released.
• Q: What is the centre-line method and when does it fail? A: Total centre-line length × thickness × height for continuous walls or partitions of uniform section; it needs corner corrections and fails where thickness changes, so the long-wall-short-wall method is used instead.
• Q: How is GST handled on a turnkey interior project? A: A turnkey fit-out is normally a composite works-contract supply of service taxed at the applicable service rate on the whole value, while loose furniture and appliances supplied as goods are taxed as goods; slabs are 5%, 18% and 40% since 22 September 2025, and the exact rate must be confirmed from the current notification and SAC/HSN.
• Q: What goes into a contingency and how much do you keep? A: An allowance for unforeseen work, typically 3-5% of the works cost, higher for renovating an occupied or old premises where concealed conditions are unknown; it is a client-held sum, not contractor profit.
• Q: Your BOQ total matched the drawings but the final bill is 14% higher. What are the likely causes? A: Provisional quantities re-measured higher, site variations and client changes, items missing from the original take-off, and extra work from concealed site conditions - traceable only if the MB entries and variation register were kept item-wise.

Common mistakes

• Mixing area bases - quoting ₹/sft on carpet area in one line and built-up in another, or pricing joinery on both front elevation and developed area.
• Adding wastage to the measured quantity *and* to the rate, so the client pays for it twice.
• Writing descriptions without specification ("modular kitchen - 1 job") so there is no basis to measure, compare bids or settle a dispute.
• Forgetting deductions for openings, or deducting where the measurement rules say no deduction is to be made.
• Omitting the quiet items - hardware, edge banding, adhesives, scaffolding, loose furniture, debris removal, protection and site electricity - which together can be 8-15% of the works cost.
• Loading taxes into the unit rate instead of showing GST separately in the abstract, which breaks tender comparison and invoicing.
• Quoting remembered statutory figures - a GST percentage, a minimum wage, a TDS section - without checking the current notification, when slabs, the Labour Codes and the Income-tax Act, 2025 numbering have all changed recently.
• Unit slips - ₹/sqm applied to a quantity in sft (1 sqm = 10.764 sft), or Rm rates applied to an area.

Related topics

Specification writing and materials for interiors · Modular furniture and joinery detailing · CAD, Revit and BIM for architects · Project management and site supervision for interiors · Professional practice, contracts and tendering · Building services and MEP coordination