Bifold internal opening first floor door

Firat a cill tray or cavity tray probably missing . Is probably silicone to be not waterproofing.Check the drainage holes on the upper bifold They must be present and must drain outward. If they are missing or blocked, the installation is defective. Require installation of a proper cill tray / cavity tray This is the key component that prevents water from entering the wall. It must: - sit under the upper bifold frame - have upstands that direct water outward - run continuously across the full width Do not close the plasterboard until the leak is fully resolved. It can cause mould, structural damage, and long‑term deterioration of the building fabric. The installer is responsible for correcting this under warranty, as it is a clear installation defect.

Hi, This appears to be a waterproofing / cavity tray issue rather than a simple door adjustment. Would need to carry out a detailed inspection to determine the source of the leak before advising on a solution and cost.