Building Regulations in Wales: Approved Document K

Wales has its own version of Approved Document K — the pre-2013 edition (with 2000 and 2010 amendments), which England has since replaced. Despite the different edition, every private-stair and guarding figure is the same as England: 220 mm max rise, 220 mm min going, 42° max pitch, 2 m headroom, 900–1000 mm handrails, 900 mm guarding (1100 mm on external balconies), the 600 mm guarding trigger and the 100 mm gap.

So in Wales you build to the same stair & guarding numbers as England — just confirm you’re on the current Welsh edition, since Wales sets its own timetable and has already diverged from England on other parts (like energy).