Yes, you absolutely need a chimney cap even if you never use your fireplace. Unused chimneys actually face greater risk of water damage, animal intrusion, and debris accumulation because they lack the regular maintenance that comes with active use. Water entering through an uncapped chimney causes serious structural damage to your flue liner, damper, and masonry. This damage occurs whether you burn fires or not, and repair costs often exceed $1,000-$3,000 depending on the extent of deterioration. Animals frequently nest in unused chimneys, creating blockages that can cause dangerous carbon monoxide buildup if you ever decide to use your fireplace again. Birds, squirrels, and raccoons all see uncapped chimneys as attractive nesting sites, and removing them safely requires professional intervention.