BOQ vs Actual Variance Analysis: Catching Cost Overruns Before They Hurt

A BOQ is a plan. The useful question during construction is how the real project compares with it. That comparison is variance analysis.

What Variance Means

Variance is the difference between a planned figure and an actual one. A positive or negative sign only matters in context: using less material than planned is good if the work is complete to specification, and a warning if the work is behind.

The Three Variances Worth Tracking

Variance	Compares	Typical cause
Quantity	BOQ quantity vs quantity actually executed	Scope change, re-measurement, rework
Material	BOM quantity vs material consumed	Wastage, theft, poor estimates, wrong mix
Cost	Budgeted amount vs amount spent	Rate changes, overtime, unplanned purchases

A Worked Example

An 18% overrun on one material, found at month end, is hard to correct. Found in week two, it is a conversation with the site engineer about mix ratios and wastage.

Acting on a Variance

1. Decide a threshold. For example, flag anything beyond a set percentage over plan.
2. Find the cause. Is it wastage, a real change in scope, or a bad estimate?
3. Fix the process or the plan. Tighten site controls, or revise the BOQ through approval if the scope has truly changed.
4. Review regularly. Weekly beats monthly.

Why Excel Struggles Here

Variance needs planned and actual figures in one place, updated as work happens. When consumption sits in tally sheets and the plan sits in a separate workbook, reconciliation becomes a month-end chore. See our guides on material tracking and budget management.

VISWOX ERP includes variance alerts, so a gap between plan and actual is flagged as it appears.

Summary

• Track quantity, material and cost variance against the BOQ and BOM.
• Set thresholds and review weekly.
• Find the cause before deciding whether to fix the site or the plan.