Until a couple of years back, curbs were built without pan corners at each finish. In case your shower curb does not have pan corners, you will notice water damage and mould or water leaks at both sides from the curb. Sheetrock might be wet or stained. Paint on base moulding will turn mouldy or discoloured. Linoleum floor alongside it might be rusted close to the ends from the curb with nowhere else! So search for these common signs.