A policy with a sum insured below the true replacement cost does not simply cap large claims. Under common terms it can reduce every claim proportionally, including small ones.
Average clauses scale the payment
Many property policies contain a condition applying where the sum insured falls short of the value at risk. The settlement is reduced in the same proportion as the shortfall.
Insuring for three-quarters of the correct figure can therefore mean receiving three-quarters of an otherwise valid claim, even where the loss is far below the sum insured.
The logic is that the premium paid covered three-quarters of the exposure, so the cover responds accordingly.
Replacement cost is not market value
Buildings cover is normally based on the cost of rebuilding, which includes demolition, professional fees and compliance with current standards. It bears no fixed relationship to what the property would sell for.
In some markets rebuilding costs exceed market value; in others the reverse holds because land dominates the price. Using the wrong figure produces error in either direction.
Contents cover similarly depends on the cost of replacing items rather than what they would fetch second hand.
Values drift upward quietly
Construction costs and contents values rise over time, while a sum insured set at policy inception stays where it was placed unless it is revisited.
Index-linking on renewal helps but applies a general adjustment that may not track the specific costs involved, particularly after periods of sharp materials inflation.
Renovations, extensions and significant purchases change the exposure immediately and are a common source of unnoticed shortfall.
Business cover has additional traps
Business interruption cover depends on an indemnity period that must be long enough for the operation to actually recover. Too short a period truncates the claim regardless of the sum insured.
Stock and equipment values fluctuate through the year, so a figure set at a quiet point can be well below the exposure at a busy one.
These conditions are set out in the policy schedule, which is where the assumptions behind the price are recorded.
Why the gap is discovered late
Nothing in the premium or the documentation signals a shortfall until a claim is assessed, because the insurer values the loss only when one occurs.
Periodic review against current rebuilding and replacement costs is the only mechanism that catches it, and professional valuation is usual for larger risks.
Terms differ between policies and jurisdictions, so the specific wording of the policy in force determines what actually applies.