In Dallas, an open flue is an open invitation — to wildlife and to storm water alike. A long warm season means birds and squirrels nest in uncapped chimneys year-round, and when a DFW storm hits, an open flue takes the rain straight into the structure. A correctly sized, sealed cap closes both problems for a fraction of what the damage costs.
Installation is precise or it's pointless: measured to your flue tile, anchored and sealed so storm winds can't lift it, meshed so animals can't enter and sparks can't exit. Galvanized is the standard for single flues; multi-flue caps are stainless only — Texas sun and storms punish anything less. If the crown shows UV crazing while we're up there, it's photographed and gets a separate quote for Dallas crown and masonry repair.