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Richard Bailie Tech Talk: lack of ducts in residential class buildings (Part 3)

    • SANS 10252-2: Water supply and drainage for buildings Part 2: Drainage installations for buildings
    • SANS 10400-P: The application of the National Building Regulations Part P: Drainage
    • For plumbers to be able to comply with the installation standards of drainage, therefore in at least a one-pipe system it requires good access to the pipes in terms of SANS 10252.

This is part 3 of a three-part article which have to be read together for the full presentation.

The purpose of venting

Obviously there needs to be ventilation. But how many of us see vent stacks protruding out of the middle of residential streets? It doesn’t happen, but the municipality has got hundreds of thousands of kilometres of sewage pipes which need ventilation. You cannot permit a build-up of methane, an explosive gas, without venting it.

Venting is stipulated through the standards which describe how to vent properly, and where to place vents. Our houses are the vents for the municipal lines – so they’re not just for us and for our individual property but part of a municipal system.

Just because a customer can live with a gurgling bath, that doesn’t make it compliant. You’ve got to have ventilation for municipal purposes, as well as your own purposes. When regulations talk about at least one open vent from the highest point of the sewer system at each property – that’s what the requirement is.

What are the consequences?

The consequences are:

    • having to demolish parts of the building to access the pipe
    • inability to pinpoint leaks, or
    • damage to pipes

In the latter case, often if the pipe is built inside a wall, a big area of it may start to discolour and become damp, without the plumber knowing where to chop. You can choose an area but five times out of 10 it’s the wrong place and you have to start again elsewhere.

Yet most houses are designed and bought like that, knowing full well the wall will have to be chopped sooner rather than later when there’s a water leak or blocked sewer. Leaks damage the structure instead of being contained within a duct and discharged at the bottom of a duct. If the pipes are rigidly enclosed within a structure, and there are stresses within that structure, it could damage the pipe just from the movement of the building itself.

What to do?

Plumbers should question architects or developers on the standards and inform them what the consequences could be. Discuss the requirements with all the necessary parties immediately you see the problem – when you see it on the plans at the quoting phase.

Ask ‘Where’s the ducts’, then outline the consequences of not having ducts. You don’t have to get into arguments, simply state the facts and let them make up their own minds.

Written by Eamonn Ryan based on an IOPSA Tech Talk by Richard Bailie on lack of ducts in residential class buildings

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