BUILDING REGULATIONS
Soil and Waste installations must be designed to comply with the following:

• The Building Regulations 2002, Approved Document H, Section H.1

• Building Standards (Scotland) Regulations 1990, Part M

• The Building Regulations (Northern Ireland) 1990,Technical Book N, Section 1

Comprehensive guidance on the design of soil and waste systems is given in BS EN 12056:2000 Gravity Drainage Systems inside buildings. Following the recommendations of this Code is also deemed to satisfy the requirements of the above Building Regulations.

All information in this Product Guide is based on the above documents, which should in any case be consulted for all installations.

All sanitary discharge system designs should be evolved by all professions involved in a building’s construction. Positioning of appliances and associated pipework can have important implications both for the materials and time required for assembly. Extensive guidance is also provided in BS 6465:Part 1:1984:Code of practice for scale of provision, selection and installation of sanitary appliances.

UNDERGROUND DRAINAGE
It is necessary to dispose of the waste collected by Brett Martin Soil and Waste Systems in an efficiently designed underground drainage system. Complete Brett Martin Underground systems are available for this application, in diameters from 110mm to 400mm, and are detailed in the Brett Martin Drainage Product Guide.

PERFORMANCE CRITERIA.
In order to satisfy National and Local Regulations, a well designed and installed sanitary waste system will satisfy the following basic criteria:

1. Be of sufficient capacity, with appropriate pipe sizes and gradients, to convey foul water to a suitable drainage system for disposal.

2. Have minimal risk of blockage or leakage and be provided with access for inspection and cleaning.

3. Prevent foul air from entering the building under normal working conditions, through provision of water seal traps.

4. Be ventilated to maintain water seal integrity.

5. Be fixed securely to cope with structure and environmental conditions and changes.

WASTE TRAPS
Every appliance which discharges into a soil and waste system must be fitted with a water-sealed trap which will prevent foul air from within the system entering the building. Under test and working conditions, traps should retain a minimum water seal of 25mm. All traps must be removable, or fitted with a cleaning eye to give access for clearing blockages.

For each appliance there is a minimum trap size and seal depth which must be used.These are given in the following table:

TYPICAL MINIMUM TRAP SIZES AND SEAL DEPTHS

* The appliances indicated, when situated on a ground floor and discharging directly to an external gully, may have the seal depth reduced to a minimum of not less than 38mm.

In BS EN 12056-2:2000 Sanitary Pipework Layout Calculation, there is a recommended trap water seal depth of not less than 38mm. However in some areas a 19mm seal is found to be acceptable and, to suit customer requirements, traps WBT604 and WBT608 are offered. Clarification on the suitability of these shallow traps should be sought from the relevant local Building Control department. Another alternative is the 50mm seal trap, WBT602.

The waste pipe connected to a trap must not be of a smaller diameter than the trap outlet. Where the waste pipe is larger than the trap outlet, the outlet should be extended by 50mm before the connection to the larger size pipe.