Towers, spires, steeples, and other roof structures made of combustible materials must not extend more than ____ ft above the allowable building height.

Towers, spires, steeples, and other roof structures made of combustible materials have specific height restrictions to ensure fire safety and structural integrity. The correct limit for such features is 20 feet above the allowable building height. This guideline is important because it balances aesthetic considerations with safety concerns. Structures that extend significantly above the main building height can be more susceptible to wind forces and other environmental impacts, and using combustible materials for these extra heights poses increased fire risks. By permitting a maximum extension of 20 feet, building codes aim to mitigate these risks while still allowing for architectural expression.