In areas with a history of ice forming along the eaves, what is the requirement for the ice barrier?

In areas prone to ice formation along the eaves, the building codes require the installation of an effective ice barrier to prevent water intrusion and potential damage to the structure. The correct choice specifying that three layers of underlayment cemented together is necessary is grounded in the understanding that this layered approach creates a more robust defense against both water and ice.

Increasing the number of layers enhances the barrier's ability to withstand the effects of ice dams, which can occur when snow melts and refreezes at the eaves. The additional layers provide added strength and better sealing against the elements, ensuring that water does not penetrate the roofing system into the underlying materials.

In contrast, simply using one or two layers may not offer sufficient protection against the potential hydrostatic pressure created by ice buildup, which can lead to leaks and structural damage. Additionally, completely foregoing an ice barrier would not meet the requirements for areas experiencing such weather patterns and poses a greater risk of moisture intrusion, underscoring the importance of the specified three-layer barrier in safeguarding the property.