The duty to defend is your insurer's obligation to provide and pay for your legal defense when a covered claim or lawsuit is filed against you. This duty is broader than the duty to indemnify (pay the claim). Your insurer must defend you if there is even a possibility that the claim could fall within your policy's coverage, based on the allegations in the complaint. The insurer pays for attorneys, expert witnesses, court costs, and other defense expenses.
For roofing contractors, the duty to defend is one of the most valuable features of a CGL policy because lawsuit defense costs can easily reach $50,000 to $200,000 even when the underlying claim is frivolous. If a homeowner sues you alleging your roofing work caused mold damage, your insurer must provide a defense even if the claim is questionable, as long as the allegations potentially fall within your coverage. The defense costs are typically paid in addition to your policy limits, meaning they do not reduce the amount available to pay the actual claim.
Some policies, particularly those with self-insured retentions or certain excess policies, include defense costs within the policy limits rather than in addition to them. This "defense within limits" or "eroding limits" structure means every dollar spent on defense reduces the amount available to settle or pay a judgment. If your policy uses this structure, a prolonged defense can consume a significant portion of your coverage. When comparing policies, always ask whether defense costs are inside or outside the limits, as this fundamentally changes the value of the coverage you are purchasing.