A chimney without a cap allows moisture from rain and snow to be absorbed into your the inner flue tile, outer bricks and mortar. When this trapped moisture goes through a freeze/thaw cycle, the integrity of the chimney's structure becomes compromised, creating a safety hazard. Home heating and cooling costs can escalate when a proper damper is not installed, allowing air to escape through the chimney flue. At the same time, wildlife, insects and debris can create further hazards inside an uncovered chimney flue.