Waterproofing Cost Breakdown for Quantity Surveyors — Ghana 2026 (BOQ Rates, Take-Off Methodology, Worked Example)
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FOR QUANTITY SURVEYORS
BOQ-format unit rates, take-off methodology, material quantities, waste allowances, and a fully priced worked example. Practical numbers you can use in your next tender.
Waterproofing is one of the most consistently mis-priced sections in Ghanaian BOQs. This guide provides the 2026 unit rates we use when pricing waterproofing work — the same numbers you can build into your own tender.
All rates are for the Ghanaian market, exclude VAT, and assume standard access conditions.
BOQ Unit Rates — 2026 Ghanaian Market
Roof and Slab Waterproofing
| DESCRIPTION | UNIT | RATE (GHS) |
| Single-coat PU liquid membrane on concrete slab (not a waterproofing specification) | m² | 50 – 80 |
| Two-coat PU liquid membrane on concrete slab (recommended) | m² | 80 – 130 |
| Fleece-reinforced PU membrane on high-movement zones | m² | 180 – 280 |
| Bituminous torch-on membrane (single ply) | m² | 80 – 130 |
| Self-adhesive bituminous membrane | m² | 90 – 150 |
Wall, Parapet, and Vertical Surfaces
| DESCRIPTION | UNIT | RATE (GHS) |
| Fleece-reinforced PU membrane on parapet walls | m² | 180 – 280 |
| Two-coat PU on parapet without reinforcement | m² | 100 – 160 |
| Exterior wall waterproofing coat | m² | 55 – 100 |
| Chemical DPC injection (linear run of wall) | lin m | 400 – 800 |
Gutters and Drains
| DESCRIPTION | UNIT | RATE (GHS) |
| Metal box gutter fleece-reinforced PU (rust-treated substrate) | lin m | 200 – 320 |
| Concrete gutter two-coat PU | lin m | 120 – 220 |
Foundation and Below-Grade
| DESCRIPTION | UNIT | RATE (GHS) |
| Positive-side foundation membrane + protection board | m² | 120 – 200 |
| Cementitious crystalline waterproofing (interior negative-side) | m² | 100 – 160 |
| DPM under-slab (polyethylene sheet + lapping) | m² | 25 – 50 |
Bathroom, Water Storage, Special Areas
| DESCRIPTION | UNIT | RATE (GHS) |
| Bathroom pre-tile PU membrane (floor + wall to 1.8 m) | m² | 180 – 280 |
| Water storage tank potable-rated PU lining | m² | 150 – 240 |
| Swimming pool composite (crystalline + PU + tile) | m² | 250 – 400 |
| Butyl rubber tape (per lin m installed) | lin m | 30 – 80 |
| Waterproof leakage spray (localised, per litre) | L | 100 – 150 |
Material Take-Off — The Check That Catches Under-Priced Bids
Verified rate: 0.41 kg/m² across two coats
From a documented Fest Ghana project at Kpone Katamanso: 150 kg of single-component polyurethane over 370 m², two coats. That is roughly 25 m² of finished membrane per 10kg bucket, or 12 m² per 5kg bucket. Use 0.40–0.45 kg/m² for take-off on sound concrete; increase for porous, rough or never-sealed substrates.
| Measured area | Coating required (2 coats) | 10kg buckets |
|---|---|---|
| 100 m² | ~41 kg | 4–5 |
| 370 m² (verified project) | 150 kg | 15 |
| 1,000 m² | ~410 kg | 41–45 |
| 5,000 m² | ~2,050 kg | 205–225 |
Use this in bid evaluation. Divide the kilograms of coating in a bid by the measured area. If the answer is materially below 0.40 kg/m², the bidder is pricing one coat and describing two. It is the single fastest way to spot an under-priced waterproofing package, and it is far more reliable than comparing headline rates.
Where a specification calls for dry film thickness rather than application rate, price the DFT from the specific product's technical data sheet — solids content varies materially between manufacturers, so a generic DFT assumption will misprice the package in either direction.
Quantity Take-Off Methodology
Slab and roof areas
Measured net area (m²) of horizontal slab surface. Deduct openings greater than 1 m².
Parapet walls
Measured length × face height (m²). Include both interior and exterior parapet faces plus the top coping surface. This is the most commonly under-measured item in Ghanaian waterproofing BOQs — a 50 lin m parapet at 900 mm returns 90 m², not 45.
Gutters
Measured as linear metre (lin m) of gutter run.
Wall-to-slab junctions
Measured as linear metre. Applies to butyl tape and reinforcing strip.
Penetrations
Measured as number (No.) with a rate per penetration. Typically GHS 250–800 per penetration.
Curved and pitched surfaces
Measure the developed surface area, not the plan footprint. On a curved or arched roof the developed area can exceed the plan area by 50% or more, and pricing the plan area is a straightforward way to lose money on the package.
Waste and Wastage Allowances
- Liquid membrane: add 10% wastage in complex geometries, 15% on parapets and details
- Fleece reinforcement: add 15% for overlaps and cut-offs
- Butyl tape: add 20% for overlaps
- Sheet membranes: add 12–15% for laps and cut-offs on complex geometries
Access and Adjustment Multipliers
| CONDITION | MULTIPLIER ON BASE RATE |
| Ground floor / single storey (base) | × 1.00 |
| Two-storey (ladder / trestle access) | × 1.10 – 1.15 |
| Three-storey (scaffold required) | × 1.20 – 1.35 + scaffold PC |
| Four-storey+ (cherry picker / rope access) | × 1.35 – 1.60 + access PC |
| Live building / phased work | × 1.15 – 1.25 |
| Overnight / weekend shift work | × 1.20 – 1.40 |
Worked Example — 200 m² Concrete Flat Roof, Single-Storey Home
A single-storey home with 200 m² concrete flat roof, 50 lin m of parapet wall (900 mm high, both interior and exterior faces = 90 m² parapet), 3 penetrations, 1 roof drain outlet.
| ITEM | QTY | UNIT | RATE (GHS) | TOTAL (GHS) |
| Two-coat PU on roof slab | 200 | m² | 100 | 20,000 |
| Fleece-reinforced PU on parapets | 90 | m² | 220 | 19,800 |
| Butyl tape at wall-slab junction | 50 | lin m | 50 | 2,500 |
| Penetration detailing | 3 | No. | 500 | 1,500 |
| Drain outlet detailing | 1 | No. | 800 | 800 |
| Water test on completion | 1 | Item | 1,000 | 1,000 |
| Subtotal | 45,600 | |||
| P&G (approx 8%) | 3,648 | |||
| TENDER TOTAL (excl. VAT) | GHS 49,248 |
Material sense-check on the above: 200 m² slab plus 90 m² parapet = 290 m², requiring roughly 120 kg of coating — 12 buckets of 10kg, plus fleece and detail materials. If a competing bid for this scope shows 5 buckets, it is not pricing the same job.
What to Include in Every Waterproofing BOQ Item
- System name, number of coats, and minimum application rate in kg/m² (more enforceable on site than DFT)
- Reference to specification clause and detail drawing number
- Warranty term — workmanship and material stated separately, and design life stated separately again as a service-life expectation rather than a warranty
- Approved manufacturer list or "or equivalent approved" clause
- Material quantity reconciliation before stage certification
- Water test and handover requirement
On item 3: realistic Ghanaian terms are 3 years workmanship and 3 years material, on systems with a 20-year design life. Specifying a 10-year or 20-year warranty will disqualify every bidder who answers honestly.
Free QS Support
- QS professionals: 0241 737 026
- WhatsApp: Chat with our estimating team — send drawings or areas for a written material take-off
Related Professional Resources
- Waterproofing BOQ — How to Write and Price It
- Architect Specification Guide
- Warranty & Insurance in Waterproofing Contracts
- Consumer Cost Guide 2026
Festghana Waterproofing Solution Company Limited provides pricing support, tender review, material take-offs, and installation services for professional waterproofing projects across Ghana. 3-year workmanship warranty on every installation.