Kim Morris looks at the right methods for the installation of above-ground sanitary systems, paying particular attention to the recommendations in Approved Document H.

To correctly install, commission and test above-ground sanitary and rainwater systems, it is recommended that reference to Approved Document H: Drainage and Waste Disposal 2002 Edition (ADH) be made in England and Wales. Similar guidance applies to other parts of the UK. The guidance provided in this Approved Document covers areas such as:
• H1 Foul water drainage
• H2 Wastewater treatment systems and cesspools
• H3 Rainwater drainage
• H4 Building over sewers
• H5 Separate systems of drainage
• H6 Solid waste storage

This article will cover the requirements for above-ground systems and sizing of the discharge stack installed in single dwellings, multi-storey flats and non-domestic buildings.

It is often said a design flow rate of 5.2 l/sec within the discharge stack will always be satisfied by the fitting of a 100mm size pipe installed within a primary ventilated system – although the vent pipe may be reduced to 75mm if required. This is fundamentally true and it is for this reason that plumbers need not normally make any decisions or calculations when installing a discharge stack, especially within a domestic dwelling.

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