Technical Booklet N Drainage·Page 16·Diagram 2.5(a)
Branch pipe slope requirements
This table specifies minimum and maximum slopes for different appliance trap connections to ventilated stacks, varying by pipe diameter and appliance type.
Unvented branch connections to stacks - WC: slope 18 mm/m (min), 6.0 m (max) for single WC; Washbasin: see para 2.12; Sink: slope 18 mm/m (min), 3.0 m (max) for 40 mm pipe, 4.0 m (max) for 50 mm pipe; Bath: slope between 18 and 45 mm/m for 42 mm pipe, 1.7 m (max) for 32 mm pipe, 3.0 m (max) for 40 mm pipe; slope between 18 and 90 mm/m, 3.0 m (max) for 40 mm pipe, 4.0 m (max) for 50 mm pipe.
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