Menu Close

Richard Bailie Tech Talk: lack of ducts in residential class buildings (Part 1)

    • 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 1 of a three-part article which have to be read together for the full presentation.

The fact is that ducts are often not part of the design of a building. At some point in our plumbing careers, we have all required a duct and either lamented that a duct is not there, or grateful that it was there. How often have we been asked to put sewer stacks and waste pipes chased in the wall, which is not optimum for the structural stability of the wall. It completely contradicts the requirement that pipes be accessible,

There is one standard in particular, SANS 10252-2: Water supply and drainage for buildings Part 2: Drainage installations for buildings; and SANS 10400-P:  The application of the National Building Regulations Part P: Drainage – which talk about ducts and their specific requirements.

Under these standards, plumbers can’t just be asked to put a pipe in a wall. It’s been happening for decades, but we as plumbers need to wake up and take responsibility to inform the designer or architect and the owner that it’s not right, by showing them the correct standards.

The people who make decisions regarding the design of a buiIding – whether the architect, designer, developer or the owners – don’t want to see pipes or vents on the outside – often without being cognisant of the ramifications of that.

What plumbers face on a regular basis is those developers having been very clever in finding invisible places to put pipes in brand new developments, with for instance geysers in cupboards in a bedroom. But to make that work it has all the wrong junctions and sewer stack that are inaccessible. The challenge for plumbers is how do access it without causing damage?

In the above example I saw recently, the sewer line and waste line were in a bedroom cupboard in each apartment of each of seven stories. The nature of a sewer line is that it’s going to leak at some point in its life no matter how robust those joints and fittings. To require in the plans that a plumber place a stack like that in a cupboard is irresponsible – yet this is the sort of things that we are often forced to do.

What the standards say

SANS 10252-2 section 6.7.3 talks about duct work: It says the following considerations must be taken into account among others, “where a discharge pipe is located in any building and it is desired that such a pipe be enclosed, it shall be enclosed within a duct”. It doesn’t say it shall be enclosed within a wall.

It continues, “The duct shall either be oversized and shaped that any person can readily enter it and work in it, or it shall be provided with covers that can be readily removed to enable access to be gained to all junctions, bends and cleaning eyes in that entire stack.”

In some photos demonstrated by Bailiie, he pointed out an aperture with a little door that “you can’t even fit your head in to see what’s happening, never mind work on that stack”.

Referring to the photo, he said: “I’m standing in a residential passage as you walk into the building with rooms on your left and right. There are stacks running down every second room, so that there’s about 16 of these stacks in low access hatches, inside a residential corridor, terminating on the ground floor. Any leakage just sits there inside the building – it’s not even outside.

It’s not the plumber’s fault when he gets to a building like this and cannot do his job as you have to be able to get into the stack to work on it comfortably. The plumber shouldn’t need to break down structure in order to access junctions and bends.

SANS also states “the removal of any component of the building for purpose of gaining access to any pipe shall not endanger the structural stability of the building”.

This means you shouldn’t have to go through a structural element in order to access a pipe – though it’s already stated that things must be accessible with covers that allow ready access. Then SANS says: “The means shall be provided inside the duct to direct the discharge of any released liquid or matter from the area inside the duct to a point where it is preferably readily detectable should any leak develop inside such a duct”.

There is almost an assumption that leaks will occur from sewer and waste stacks which have to be worked on and repaired. Say you have to repair a section of 110mm stack on the ground floor – you try telling all three floors above not to flush for the next three hours. It’s not going to happen. They’re going to flush and that waste has to go somewhere and you can’t allow it to flow into somebody’s apartment.

The bottom of the duct has to have a means of discharging or allowing the waste to run off – and it needs to be detectable. If a leak develops unseen in a duct, you need to be able ideally to see a visible trickle or discharge.

In the example in these photos it’s simply not the case – it just terminates on the floor. It’s a fibre cement cladding drywall, which is going to have to be broken out in order to access that and then you can’t even access it because there’s no inspection eyes on the bends.

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

Leave a Reply

Your email address will not be published. Required fields are marked *