Construction Tolerances – Formwork depth tolerance for a footing with specified thickness 100 cm.

Introduction:
Tolerances ensure constructability without compromising performance. For massive elements like footings, small dimensional variations are inevitable but must be limited to avoid capacity or cover issues.

Given Data / Assumptions:

• Footing specified thickness = 100 cm.
• Checking allowable formwork depth deviation.
• Standard good-practice tolerance bands are considered.

Concept / Approach:

Depth deviations affect bearing area, cover, and reinforcement position. A pragmatic yet tight tolerance for a 1 m thick footing is within ±5 mm for formwork depth, aligning with quality control expectations on major foundations.

Step-by-Step Solution:

Verification / Alternative check:

Rebar cover checks and cube level measurements typically keep variation within this band for heavy foundations when supervised.

Why Other Options Are Wrong:

±2–4 mm are impractically tight for 1 m thickness; ±10 mm may be permissible in some specs, but is looser than the recommended tolerance here.

Common Pitfalls:

Neglecting settlement or uplift of formwork during concreting and not re-checking levels after initial pour.

Final Answer:

-5 mm to +5 mm