ICE AND WATER BARRIER. An ice and water barrier is required on all roofs except for detached accessory buildings (garages). The barrier may be at least two layers of underlayment cemented together or a self-adhering polymer modified bitumen sheet. There are several manufacturers who make materials specifically for this requirement that are marketed under differing trade names. The ice and water barrier must extend from the edge of the eaves to a point 24 inches inside the exterior wall line of the building. Ice and water barriers are required full-length in valleys (see picture on page 4 of this handout). The above noted ice and water protection requirements pertain to conditioned and unconditioned spaces. Ice and water protection is required on all attached garages.