🔹Rafting in Construction: What Is Raft Foundation (Rafting)?

A raft foundation is a large reinforced concrete slab that supports the entire structure and spreads loads evenly over weak or variable soil.

Used where soil bearing capacity is low

Supports closely spaced columns

Reduces differential settlement

Common in basements and high-load buildings

🔹Rafting in Construction: Why Rafting Is Important in Construction

Rafting improves structural stability and long-term safety by distributing loads uniformly.

Minimizes cracks and uneven settlement

Increases foundation stability

Suitable for seismic and weak-soil areas

Reduces risk of foundation failure

🔹Rafting in Construction: Step-by-Step Raft Foundation Construction

Rafting follows a planned sequence to ensure strength and safety.

Soil investigation and design approval

Excavation to required depth

PCC (50–100 mm) for clean base

Waterproofing or polythene sheet

Bottom and top reinforcement fixing

Formwork installation

Continuous concreting with vibration

Proper curing (7–14 days)

🔹Rafting in Construction: Typical Measurements (General Range)

Actual sizes depend on design, but common ranges are used on sites.

Raft thickness: 300–1000 mm

Reinforcement spacing: 150–300 mm c/c

Concrete grade: M25–M35

Clear cover: 75 mm bottom / 50 mm top

Excavation depth: 1–3 meters

🔹Rafting in Construction: Potential Hazards During Rafting

Rafting involves high-risk activities at foundation level.

Excavation collapse or cave-in

Falls into open excavations

Rebar cuts and impalement

Formwork collapse

Cement burns and skin irritation

Electric shock from vibrators

Heat stress and poor visibility

🔹 Rafting in Construction: Control Measures (Safety Actions)

Effective controls reduce accidents and delays.

Excavation shoring or proper sloping

Barricading and warning signage

PPE: helmet, gloves, safety shoes, goggles

Rebar caps on exposed steel

Safe access ladders and lighting

Equipment inspection and earthing

Emergency response plan

🔹 Rafting in Construction: Duties of a Safety Officer During Rafting

The safety officer ensures safe execution at every stage.

Review risk assessment and method statement

Conduct toolbox talks before work

Monitor excavation stability and access

Ensure safe rebar and formwork practices

Supervise concreting and electrical safety

Enforce PPE and site discipline

Report and stop unsafe acts

These duties align with guidance from the International Labour Organization and Occupational Safety and Health Administration for construction and excavation safety.