Drainage problems with a new house.

Problems with drainage to a new house became a reality soon after the buyers shifted into this new house. After they were pre-warned, by Peter Weddell of QBIS.

Drainage issues:

  • Paved area with less than 50 mm between levels of the outside and inside with inadequate drainage.
  • Water entry occurred to the lower living area, not long after the buyers shifted into this new house!
  • Undersize drains for the catchment area also overland flow of water.

The paving should also have been laid at least 150 mm lower than the slab level of the living area, with much larger drains fitted.

New house with drainage problems

Insufficient drainage to bottom of these steps.

Both sides of these steps lead down to two undesized drains with only 50mm step up from the paving level to inside of the house.

No safety railing!

Try explaining this to your insurer when someone seriously injures themselves from a fall!

Drainage issues with a new house

Existing drains.

Accumulation of debris will occur within them over time. Drains must be periodically checked for possible damage (that can be caused by tree and shrub roots). They must be kept clear of debris to operate effectively.

Seepage into a living area.

Seepage was also a problem through a block retaining wall not having been properly drained and waterproofed, during its construction.

Causes of drainage problems:

  • Not allowing for extreme weather conditions when calculating capacity of the surface drainage system.
  • Trees and roots.
  • Undersize and insufficient number of drain pipes.
  • Combining roof and surface drains.
  • Not considering overland water flow.
  • Levels of surrounding properties being higher.
  • Insufficient level differences between paving and the inside slab.


These problems could not be easily rectified without major modification.  This is not what you would expect and want to have to deal with when buying a newly built, large and expensive house.

Drainage problems with a new house. Some information that may be of use:

Qld Govt Water-complaints/stormwater/runoff and drainage

For independent Building Inspections Brisbane in all suburbs, Qld Home Buyers Inspection Service. qbis.com.au