The in-flat section and the shared section
The in-flat section consists of fixture traps and connecting pipes up to the stack. The shared section is the stack and the building's drop pipe up to the outlet on the property. The location of the clog determines whether the work concerns one flat or the whole stairwell.
- only one fixture clogged — likely in-flat
- several fixtures at once — connecting pipe or stack
- water rises in lower-floor flats — the building's drop pipe
How the work is carried out in practice
For the shared pipework, access to an inspection hatch is needed, often in the basement or near the lowest floor. During the work it's sensible to inform residents not to use water, since water can come out through an open inspection hatch.
If the clog recurs in the same spot, the pipe is inspected with a camera. This reveals whether the cause is sediment, an incorrect slope, a sunken section, or roots that have grown in.
What the housing association can do in advance
For recurring clogs, a common solution is scheduled pressure flushing of the stacks and drop pipe along with an inspection. This gives an understanding of the pipework's condition before the next clog sends water into a flat.
How to assess the clog's location before the work
The simplest indicator is how many fixtures and how many flats are affected. If water rises in the kitchen and bathroom at the same time, it's the connecting pipe or the stack. If water rises from the floor drain in a lower-floor flat, the clog is in the building's drop pipe, not in the flat above.
In older apartment buildings the stacks are often cast iron. Their inner surface has worn rough over the years and sediment sticks more easily, which is why clogs in the same building tend to recur in specific stacks.
Access and approvals
Work on the shared pipework usually requires access to the basement, a utility room, or a flat on the lowest floor. Access is normally arranged by the board or the management company, since the work takes place in a shared part of the building and may require temporarily shutting off the water.
If access to the inspection hatch has been built over, it must first be opened up. This often determines the scope of the work more than the clog itself.
What the housing association should note when ordering
- how many flats and which floors are affected
- where the nearest inspection hatch is and whether it's accessible
- whether clogs have recurred before in the same stack
- whether there are signs of water in the basement or on the lowest floor
- who arranges access and informs the residents
Frequently asked questions
- Who orders the clearing of a clog in an apartment building?
- The in-flat section is usually ordered by the flat's owner, while the shared stack and drop pipe are ordered by the housing association or management company. The exact division follows the association's agreements.
- Can a flat owner clear a clog in the shared stack themselves?
- From inside a flat, only that flat's own section up to the stack can be opened. Work on the stack and drop pipe requires access to an inspection hatch in the shared part of the building and stopping water use, which is why the association or management company arranges it.