<p>Postoperative cerebrospinal fluid (CSF) leakage remains one of the most challenging complications of transsphenoidal surgery (TSS). Numerous reconstruction techniques have been proposed, but none has been established as the gold standard. To address this issue, we standardized rigid sellar floor reconstruction using a hard buttress, based on the concept of counteracting the water-hammer effect of pulsatile CSF pressure. We retrospectively analyzed 1,168 consecutive TSS procedures for sellar lesions performed by a single surgeon between October 2004 and March 2024. Routine rigid reconstruction was implemented from January 2009 (Group B, <i>n</i> = 856) and compared with an earlier cohort without routine buttressing (Group A, <i>n</i> = 312). Reconstruction materials included autologous bone grafts, calcium phosphate cement, titanium mesh, and resorbable plates. Rigid reconstruction was performed in 885 cases, most commonly with autologous bone (<i>n</i> = 781), which proved most reliable. Calcium phosphate cement occasionally caused inflammatory change or graft dislodgement, and titanium mesh complicated reoperations. Postoperative CSF leakage requiring reoperation was significantly reduced from 2.88% in Group A to 0.47% in Group B (<i>P</i> = 0.002), despite a higher intraoperative leak rate in Group B (76.5% vs. 54.2%, <i>P</i> &lt; 0.0001), particularly grade 3 leaks (30.4% vs. 11.2%, <i>P</i> &lt; 0.0001). All postoperative leaks in Group B were attributable to inadequate buttressing. Rigid sellar floor reconstruction is a fundamental strategy—together with dural suturing and vascularized mucosal flaps—for safer and more extensive resections in modern TSS, supported by a physiological rationale based on the water-hammer effect.</p>