Do drop down seals need to be used with a threshold plate?

No, drop-down seals and automatic drop seals do not necessarily require a threshold plate to function correctly. Whilst many drop seals are fire tested and acoustically tested with threshold plates, a threshold plate is not always required, depending on the application, floor finish and performance requirements. Threshold plates can help provide a consistent sealing surface and may improve acoustic, smoke or sealing performance in certain installations. Always refer to the product datasheet, fire test evidence and installation guidance to determine the most suitable configuration for your door set.