This class covers all waterproofing treatments, membranes, coatings, and barriers applied to buildings, structures, or underground works to prevent water ingress or dampness.
1. Scope
Includes:
- Membrane waterproofing (bituminous felt, polyethylene, EPDM, PVC, HDPE, SBS/APP modified membranes).
- Liquid applied waterproofing (bitumen-based, acrylic, polyurethane, cementitious slurry, epoxy).
- Integral waterproofing admixtures in concrete or plaster.
- Waterproof rendering, coatings, and damp-proof treatments.
- Protective layers over membranes (screed, plaster, insulation boards).
- Drainage mats, geotextile, protection boards.
- Joints and sealants (water bars, hydrophilic strips, polyurethane sealant).
- Special systems – crystalline waterproofing, injection grouting, negative-side waterproofing.
2. Subdivision of Items
Waterproofing items are classified according to:
- Type of treatment
- Membrane waterproofing (torch-applied, self-adhesive, loose laid).
- Liquid applied waterproofing (coating, slurry, PU, epoxy).
- Integral waterproofing admixtures.
- Joint waterproofing (sealants, water bars, tapes).
- Special systems (crystalline, injection, damp-proof courses).
- Location of application
- Roofs and terraces.
- Basement floors, raft slabs, retaining walls.
- Podiums, sunken slabs, balconies, toilets, wet areas.
- Tunnels, tanks, water-retaining structures.
- Thickness and number of layers
- e.g., 2 mm thick APP membrane, 3 coats of PU coating, 25 mm thick waterproof screed.
3. Method of Measurement
- Waterproofing membranes & coatings – measured in square metres (m²) of the treated area.
- Integral waterproofing admixtures – measured in cubic metres (m³) of concrete/plaster in which admixture is added.
- Water bars/sealants – measured in linear metres (m) of joints treated.
- Injection grouting – measured in number (No.) of holes or in litres of grout injected.
- Damp-proof course (DPC) – measured in m² by thickness and material type.
Deductions:
- Openings > 0.5 m² deducted.
- No deductions for small penetrations (e.g., pipe holes, <0.5 m²).
4. Item Coverage
Each waterproofing item includes:
- Surface preparation – cleaning, wire brushing, priming.
- Supply and laying/applying of materials.
- Overlaps, joints, laps, sealing, and terminations.
- Protection layers (if specified in BOQ).
- Curing, testing (ponding test for roofs, water tightness test for tanks).
- Scaffolding, staging, safety measures.
5. Notes for BOQ Preparation
- State type of waterproofing system (APP, PU, epoxy, crystalline, etc.).
- Mention location (roof, basement, toilet, terrace, tank, tunnel).
- Specify thickness/number of coats/layers.
- Clarify testing requirements (ponding test, pressure test, etc.).
- Indicate whether protective screed, plaster, or insulation is included or separate.
- For admixtures, mention dosage and IS/ASTM standard.
6. Example BOQ Items
- W.1.1: Providing and laying 3 mm thick APP modified bituminous membrane with 100 mm side laps, torch applied on primed RCC roof slab, including termination details, measured per m².
- W.1.2: Providing two coats of polyurethane liquid applied waterproofing membrane @ 1.5 mm DFT on sunken floor, measured per m².
- W.1.3: Providing cementitious crystalline waterproof coating, two coats, on internal face of basement retaining wall, measured per m².
- W.2.1: Supplying and fixing 230 mm wide PVC water bar at construction joints in raft foundation, measured per linear metre.
- W.2.2: Providing and injecting cement-sand grout into cracks and honeycombs using packers, measured per litre.
- W.3.1: Providing integral waterproofing admixture conforming to IS 2645 @ 1 kg/50 kg cement, measured per m³ of concrete.
- W.4.1: 25 mm thick cement sand mortar (1:3) waterproof screed mixed with integral waterproofing compound, measured per m².
- W.5.1: Providing and laying 40 mm thick damp-proof course with M20 concrete mixed with waterproofing admixture, measured per m².
✅ In summary:
Class W covers all waterproofing works – membranes, coatings, admixtures, water bars, sealants, and special systems. Measurement is in m² (surface), m³ (concrete with admixtures), m (joints), litres (grout), or No. (injections). BOQ must specify type, thickness, coats, and testing requirements
