This class covers metal items that do not fall under structural metalwork (Class M) but are still essential for civil engineering and building works. These are typically secondary, non-structural, or functional metal components such as gratings, covers, railings, frames, gates, doors, steps, ladders, and fittings.
1. Scope of Class N
- Encompasses metal fabrications and accessories that are not primary load-bearing structural members.
- Covers items of iron, steel, aluminum, brass, bronze, or other metals.
- Applies to works like:
- Manhole covers, gully gratings, trench covers.
- Railings, balustrades, guardrails.
- Ladders, steps, catwalks.
- Frames, gates, doors, screens.
- Sundry metal fittings such as hinges, stays, locks.
2. Units of Measurement
- kg → for fabricated and installed metal items (unless otherwise specified).
- m → for linear items like railings, balustrades, ladders.
- m² → for sheet or plate items like chequered plates, doors, covers.
- No. → for discrete items like manhole covers, gates, gratings, steps.
3. Method of Measurement (as per CESMM4 rules)
- Net weight or dimensions of finished items are taken (no rolling margins).
- Fixing, handling, and erection are deemed included in the description.
- Protective finishes (painting, galvanizing, powder-coating) are measured separately in m².
- Fittings (hinges, bolts, stays, handles, locks) are included with the principal item unless specifically described otherwise.
4. Itemization & Description Rules
Items in Class N must clearly describe:
- Type of item (grating, cover, ladder, railing).
- Material and grade (cast iron, ductile iron, mild steel, stainless steel, aluminum).
- Finish (galvanized, primed, painted, powder-coated).
- Size or weight (load capacity for covers, dimensions for railings, thickness for plates).
- Function or location (road gully cover, roof access ladder, parapet railing).
5. Typical Items under Class N
(a) Manhole & Access Covers
- Ductile iron / cast iron manhole covers.
- Gully gratings, frames, trench covers.
- Measured per item (No.) or kg.
(b) Railings & Guardings
- Mild steel / stainless steel railings for parapets, staircases, platforms.
- Guardrails and balustrades for bridges, retaining walls.
- Measured per m (length).
(c) Steps, Ladders & Catwalks
- Fixed wall ladders, rungs, and catwalks.
- Access steps to tanks, manholes, or machinery.
- Measured per No. or m depending on description.
(d) Doors, Gates & Screens
- Metal doors, gates, frames, screens.
- Sliding or hinged gates for compounds or culverts.
- Measured in m² or No..
(e) Sundry Fittings
- Hinges, stays, fasteners, bolts, handles, locks.
- Measured included with item unless specified separately.
(f) Floor & Cover Plates
- Chequered plates, floor plates, trench covers.
- Measured in m².
6. Example CESMM4 Measurement Items
- Manhole Covers:
- 20 No. ductile iron heavy-duty manhole covers 600 × 600 mm, including frames, set in mortar.
- Gully Gratings:
- 15 No. mild steel gratings with frames for road gullies, 450 × 900 mm, galvanized.
- Railings:
- 120 m stainless steel tubular railings, 1.2 m high, with posts, fixed to concrete parapet.
- Chequered Plate Flooring:
- 50 m² of 8 mm thick mild steel chequered plate flooring, shop primed.
- Access Ladder:
- 4 No. mild steel wall-mounted access ladders, 3 m long, galvanized.
- Gates:
- 2 No. fabricated mild steel double-leaf gates, 4 m wide × 2 m high, with hinges, lock, stay, and painting.
7. Practical Site Examples of Class N Metalwork
- Highway Works: Gully gratings, crash barrier railings, manhole covers.
- Bridges: Parapet railings, inspection ladders, drainage gratings.
- Water Projects: Tank ladders, access platforms, sluice gate frames.
- Industrial Projects: Chequered floor plates, handrails, machine guarding.
- Buildings: Balcony railings, metal doors, ventilating grilles.
✅ Summary:
Class N (Miscellaneous Metalwork) in CESMM4 includes non-structural fabricated metal items like covers, gratings, railings, gates, and ladders. Measurement is based on unit, length, area, or weight, with finishes and fittings accounted for. It ensures uniform pricing and specification clarity for all secondary but essential metal works in civil engineering projects.
