Underinsurance is the risk that behaves best right up until the moment it matters. Premiums are paid, certificates are filed, and everything looks in order — until a loss adjuster applies an average clause and a settlement lands at a fraction of the rebuild cost.

How the gap opens

It is rarely one decision. It is a valuation carried forward for six years, a warehouse extension nobody told the broker about, construction inflation that outran the index, and a business interruption indemnity period set at twelve months for a facility that would take two years to replace.

The average clause in plain terms

If the sum insured represents only 70 percent of the true reinstatement value, the insurer may settle only 70 percent of the loss — including partial losses. A modest fire in one corner of a building becomes a materially uninsured event.

Business interruption is where it hurts most

Material damage figures are at least visible. Business interruption values depend on gross profit definitions, seasonality, and a realistic view of how long recovery actually takes. Indemnity periods are the single most common thing we find set too short.

• Revalue property on a reinstatement basis at least every three years.
• Reforecast business interruption values annually, not at renewal in a rush.
• Test the indemnity period against a genuine worst case, including planning and lead times on plant.
• Tell your broker about capital projects when they start, not when they finish.

The cheap fix

Correcting underinsurance usually costs far less than people expect — a fraction of a percent on premium against a shortfall that could run to a large multiple of annual profit. It is one of the few places in risk management where the arithmetic is genuinely one-sided.