Tie-in Requirements All new roofing areas shall be fully isolated from existing roofing areas by the use of expansion joint design, curbs or perimeter parapet walls. Tie-ins of different type roofing systems and/or deck systems require a structural deck design such that there will be no differential movement at the intersection area. Wood blocking shall be incorporated in the design to permit effective attachment of the membrane.  Return to General Requirements and Considerations for the Designer