The mechanism
If the amount insured falls below a percentage of the property’s actual value required by the contract, the insurer reduces the payout in the same proportion — even when the loss is far smaller than the amount insured.
Why it exists
Without the clause, it would be rational to insure every building for a fraction of its value, betting against a total loss. The clause restores fairness among insureds in the same book of business.
It bites on partial losses
A total loss is capped by the amount insured in any event. It is the partial loss — a kitchen fire, a localized water loss — that exposes underinsurance, at the worst possible moment.
Common causes of underinsurance
An undeclared renovation, adding a garage or a finished basement, rising construction costs, or an amount set ten years ago and never indexed. The building changes; the policy does not.
The guaranteed rebuilding endorsement
Several insurers offer an endorsement undertaking to rebuild even if the cost exceeds the amount insured, subject to conditions: an amount set by their own valuation, declared renovations, and accepted annual indexing.
What to do
Declare every major renovation, have the rebuilding cost reassessed periodically — it is neither market value nor the municipal assessment — and check whether the guaranteed rebuilding endorsement is in force on your policy.
No rate, price, or recommendation on this page. Amounts and limits change: verify them with official sources before deciding.