The Two-Staircase Mandate: Design, Compliance & Contractual Fallout

Introduction

From 30 September 2026, the transition window for avoiding the ‘second staircase’ requirement closes. After this date, the rule is no longer a future issue for tall buildings - it becomes an immediate problem for any project currently in planning or already under construction.

This webinar navigates the updated Approved Document B and the threshold for residential buildings over 18 metres. It will discuss the legal implications of redesigning mid-project: who bears the cost of lost ‘saleable area’ and how do you draft ‘Change in Law’ clauses to protect clients from the shifting sands of Building Safety Regulator (BSR) guidance?

What You Will Learn

This webinar will cover the following:

• Threshold Clarity: Navigating the 18m rule and how ‘height’ is actually measured under 2026 guidance
• Transitional Provisions: How to ensure your project qualifies for the ‘grace period’
• The Economic Impact: Drafting clauses to handle the loss of net internal area (NIA) caused by extra cores
• BSR Interaction: Tips for successful ‘Gateway 2’ submissions involving fire safety design