Scope
- Covers all types of precast concrete work, whether structural or non-structural, manufactured off-site or on-site, but not cast in-situ (which belongs to Class F).
- Includes structural units, cladding, paving, fencing, pipes, culverts, and other precast elements.
- Measurement covers supply, transport, placing, jointing, and bedding unless otherwise stated.
1. General Principles
- Precast concrete is measured by volume (m³), area (m²), length (m), or number (no.), depending on the element.
- Rates for precast items are deemed to include:
- Cost of moulding, curing, handling, and transport.
- Placing in final position.
- Temporary supports (if required).
- Fixings, jointing materials, and bedding (e.g., mortar, bitumen, neoprene pads) are measured separately when not deemed included.
2. Sub-classifications under Class H
H1 – Precast Structural Units
- Beams, slabs, lintels, stairs, columns, wall panels, culverts.
- Measured by volume (m³) or by number if standardized.
- Separate descriptions for:
- Type of unit.
- Reinforced or plain.
- Finish (smooth, textured, exposed aggregate).
- Special requirements (fair-faced, architectural).
H2 – Precast Pipes and Culverts
- Concrete pipes (circular, elliptical, box culverts).
- Measurement in length (m) or number.
- Internal diameter, wall thickness, and strength class must be stated.
- Includes jointing collars or rubber rings unless otherwise specified.
H3 – Precast Kerbs, Edgings, Channels, and Pavings
- Road kerbs, channels, tactile paving slabs, manhole cover slabs.
- Measured in length (m) for kerbs and area (m²) for paving.
- Details required:
- Size, profile, type (straight, radius, drop kerbs).
- Bedding/jointing requirements.
H4 – Precast Fencing, Posts, and Similar Units
- Fence posts, struts, rails, bollards, marker posts.
- Measured by number (no.) or length (m).
- Must state cross-section, length, and finish.
H5 – Special Precast Units
- Architectural panels, cladding units, 3D façade elements.
- Includes complex profiles or decorative finishes.
- Measured by area (m²) or number (no.) depending on shape.
- Must specify surface finish, fixings, lifting anchors, etc.
3. Measurement Rules
- Standard measurement units:
- Structural units: m³ or no.
- Pipes: m or no.
- Kerbs/edgings: m.
- Pavings/tiles: m².
- Posts/fencing: no.
- Jointing & bedding:
- If mortar, bitumen, or neoprene pads are used → measured separately under relevant class (not included in precast).
- Holes/openings in precast units:
- Deducted if >0.5 m² (smaller ignored).
- Lifting anchors, recesses, chamfers → deemed included in precast rate.
4. Information Required in Bill Descriptions
- Type of unit (pipe, kerb, beam, panel, post, etc.).
- Size/shape (diameter, length, thickness, profile).
- Material (plain or reinforced concrete, strength class).
- Finish (smooth, textured, decorative, fair-faced).
- Fixing method (bedded in mortar, bolted, dowelled, dry jointed).
- Special requirements (acid-resistant, waterproof, coloured concrete).
5. Example BOQ Items (Class H)
- Supply and lay precast reinforced concrete pipes, 600 mm dia, with rubber ring joints, laid to line and level, including lifting and placing, per metre.
- Precast plain concrete kerbs, straight, 300 × 150 mm, laid on 100 mm concrete bed, per metre.
- Precast reinforced concrete lintel beams, 200 × 150 mm, 2.0 m span, fair-faced, per number.
- Precast paving slabs, 450 × 450 × 50 mm thick, laid on sand bed, per m².
- Precast reinforced concrete cladding panels, smooth finish, 1.5 × 2.0 m, fixed to structure, per number.
- Precast reinforced concrete fence posts, 2.5 m long, 125 × 125 mm section, per number.
✅ Summary
- Class H = Precast concrete (structural + non-structural).
- Measured by volume, area, length, or number depending on type.
- BOQ descriptions must specify type, size, reinforcement, finish, and fixing method.
- Jointing and bedding are measured separately unless integral.
- Covers structural units, pipes, paving, kerbs, fencing, and cladding.
