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, 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. Under-priced tenders lead to contractor cost-cutting on site. Over-priced tenders lose the job entirely. This guide provides the 2026 unit rates, take-off methodology, and waste allowances 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 (single storey, no scaffolding, unrestricted site). Access allowances and other adjustments are covered separately below.
BOQ Unit Rates — 2026 Ghanaian Market
Roof and Slab Waterproofing
| DESCRIPTION | UNIT | RATE (GHS) |
| Single-coat PU liquid membrane on concrete slab | m² | 80 – 140 |
| Two-coat PU liquid membrane on concrete slab (recommended) | m² | 140 – 220 |
| Fleece-reinforced PU membrane on high-movement zones | m² | 220 – 350 |
| Bituminous torch-on membrane (single ply) | m² | 130 – 200 |
| Self-adhesive bituminous membrane | m² | 150 – 240 |
Wall, Parapet, and Vertical Surfaces
| DESCRIPTION | UNIT | RATE (GHS) |
| Fleece-reinforced PU membrane on parapet walls | m² | 220 – 350 |
| Two-coat PU on parapet without reinforcement | m² | 160 – 240 |
| Exterior wall waterproofing coat (acrylic-modified) | m² | 90 – 160 |
| Chemical DPC injection (linear run of wall) | lin m | 600 – 1,100 |
Gutters and Drains
| DESCRIPTION | UNIT | RATE (GHS) |
| Metal box gutter fleece-reinforced PU (rust-treated substrate) | lin m | 300 – 450 |
| Concrete gutter two-coat PU | lin m | 180 – 320 |
Foundation and Below-Grade
| DESCRIPTION | UNIT | RATE (GHS) |
| Positive-side foundation membrane + protection board | m² | 180 – 280 |
| Cementitious crystalline waterproofing (interior negative-side) | m² | 150 – 250 |
| DPM under-slab (polyethylene sheet + lapping) | m² | 40 – 80 |
Bathroom, Water Storage, Special Areas
| DESCRIPTION | UNIT | RATE (GHS) |
| Bathroom pre-tile PU membrane (floor + wall to 1.8 m) | m² | 280 – 420 |
| Water storage tank food-safe PU lining | m² | 220 – 320 |
| Swimming pool composite (crystalline + PU + tile) | m² | 380 – 550 |
| Butyl rubber tape (per lin m installed) | lin m | 50 – 120 |
| Waterproof leakage spray (localised, per litre) | L | 160 – 220 |
Quantity Take-Off Methodology
Slab and roof areas
Measured net area (m²) of horizontal slab surface. Deduct openings greater than 1 m² (skylights, plant openings) and add-back the up-turn onto the vertical faces of penetrations.
Parapet walls
Measured length × face height (m²). Include both interior and exterior parapet faces plus the top coping surface. Coping is typically double-counted (top surface + return).
Gutters
Measured as linear metre (lin m) of gutter run. Note that internal box gutters are measured on the developed length (including both sidewalls + base), while linear-metre rates in the table above assume standard box gutter dimensions (approximately 400 mm base + 250 mm each sidewall).
Wall-to-slab junctions
Measured as linear metre. Applies to butyl tape and reinforcing strip — not to be double-counted where the parapet and slab measurements already overlap.
Penetrations
Measured as number (No.) of penetrations, with a rate per penetration for detailing work. Typically GHS 400–1,200 per penetration depending on complexity.
Waste and Wastage Allowances
Standard allowances used in our take-offs:
- Liquid membrane: add 10% for 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, 8% on simple flat areas
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 slab
- 50 lin m of parapet wall, 900 mm high (both interior and exterior faces) = 90 m² parapet
- 3 penetrations (vent + 2 x plumbing)
- 1 roof drain outlet
| ITEM | QTY | UNIT | RATE (GHS) | TOTAL (GHS) |
| Two-coat PU on roof slab | 200 | m² | 180 | 36,000 |
| Fleece-reinforced PU on parapets | 90 | m² | 280 | 25,200 |
| Butyl tape at wall-slab junction | 50 | lin m | 80 | 4,000 |
| Penetration detailing | 3 | No. | 800 | 2,400 |
| Drain outlet detailing | 1 | No. | 1,200 | 1,200 |
| Water test on completion | 1 | Item | 1,500 | 1,500 |
| Subtotal | 70,300 | |||
| P&G (approx 8%) | 5,624 | |||
| TENDER TOTAL (excl. VAT) | GHS 75,924 |
What to Include in Every Waterproofing BOQ Item
To prevent contractor scope-cutting, every BOQ line item should be described with:
- System name and thickness (e.g., “Two-coat PU liquid membrane, minimum 0.8 mm dry film”)
- Reference to specification clause and detail drawing number
- Warranty term (workmanship + material)
- Approved manufacturer list or “or equivalent approved” clause
- Water test and handover requirement
Free QS Support
We provide free take-off review, unit-rate benchmarking, and BOQ template support to Ghanaian quantity surveyors on active projects.
- QS professionals: 0241 737 026 or info@festghanalimited.com
- WhatsApp: Chat with our estimating team
- Related reading: Architect Specification Guide · Consumer Cost Guide 2026 · Industrial Waterproofing
Festghana Waterproofing Solution Company Limited (trading as Fest Ghana Limited) provides pricing support, tender review, and installation services for professional waterproofing projects across Ghana. Workmanship warranty on every installation.