Internal services

Also see:

8.1.6Soil and waste systems

Soil and waste systems shall be in accordance with relevant building regulations and installed to ensure that effluent is removed without affecting health or creating unnecessary noise and smell.

Soil and waste systems should be:

  • in accordance with the requirements of the water supplier
  • adequately ventilated at the head of underground drains (this may be by a soil pipe or separate ventilation pipe)
  • adequately ventilated at each branch
  • arranged to ensure foul air from the drainage system cannot enter homes (e.g. ventilated to 900mm above openings when within 3m)
  • fixed neatly and securely to provide the correct falls
  • fitted to prevent the entry of vermin.

Air admittance valves should:

  • be used to allow air to enter the drainage system (but do not avoid the need to ventilate it adequately)
  • where used to terminate a soil pipe, comply with BS EN 12380 or be assessed in accordance with Technical Requirement R3
  • not be positioned in areas which are liable to freezing
  • have free movement of air around them which can be achieved by ventilation grilles, discreet gaps around the boxing or ventilation of the boxing into a ventilated roof void (the ventilation area should be 2500mm² minimum unless otherwise specified by the manufacturer)
  • where positioned within the home, be accessible for maintenance.

Sound insulation should be provided to soil pipes passing through homes by:

  • an encased boxing, using a minimum 15kg/m² board material and wrapping the pipe with a minimum 25mm of unfaced mineral fibre (the insulation should be continued through the thickness of each sound-insulating floor).

Sanitary fittings should be:

  • installed with accessories, such as chains and plugs
  • secured using non-ferrous or stainless steel screws or fixings appropriate to the weight of item being secured
  • fitted without using excessive packing
  • fitted to ensure WC lids and seats are stable when open.

Waste disposal units should be:

  • provided with adequate support
  • fitted with a tubular trap (not bottle or resealing)
  • connected to the drainage system in accordance with the manufacturer’s instructions.

The junctions of wall tiling with baths and showers should be made watertight using a flexible sealant to accommodate movement. The manufacturer’s instructions should be followed.