What Every Homeowner Should Know About Basement Waterproofing

What Every Homeowner Should Know About Basement Waterproofing

Flooding or dampness in the basement or semi-basement areas of your home can be frustrating, especially if you use the space for storage and your possessions become damaged from mould. Even worse, moisture issues and musty odours can often spread from the basement to the rest of your house if left untreated, causing structural damage, rot and health problems.

How do I know if I have a basement waterproofing problem?

Signs of a damp, moisture-ridden basement include:

  • Water running down the walls
  • Flooding or puddles of water on the floor
  • Condensation on walls, floor or any windows in your basement
  • Stained wall coverings
  • Mould and mildew on the walls, floor or objects stored in the basement
  • Rotting timber or carpet
  • Damp, humid air
  • Musty smell

Damp basement needs waterproofing

Why do I have a damp basement?

In Auckland, many homes have block basements (or garages with walls below ground level) that were constructed without effective subsoil drainage. Unfortunately, this can lead to dampness, mould and even flooding during rainy months when stormwater and groundwater accumulate against these walls and leak through the porous concrete blocks.

Sometimes older houses simply have no subsoil drainage system. In other cases, the existing subsoil drainage system is outdated or not functioning properly due to broken, cracked or blocked pipes, often as a result of damage from tree roots or a build up of grease, leaves and other debris in your drains.

What is subsoil drainage?

Subsoil drainage systems are installed below ground level to remove excess water from the soil and ensure that your property is weathertight.

A subsoil drainage system installed around the base of your home drains excess moisture away before it reaches the foundations, providing an effective basement waterproofing solution.

At an existing home, the installation of subsoil drainage requires a trench to be dug around the perimeter of the basement. Generally, we recommend that a waterproofing membrane is applied to the exterior wall at the same time. This membrane works in conjunction with the subsoil drainage, with the drainage system funnelling most water away from the walls while the membrane prevents any remaining water from penetrating the foundations.

Can’t I just use a waterproofing paint, dehumidifier or insulation panels?

While these types of basement waterproofing measures are inexpensive and can minimise the symptoms of dampness temporarily, they generally won’t fix the problem in the long term.

Waterproofing sealants or paints applied to the interior walls of your basement typically deteriorate over time if there is excess exterior moisture around the foundations.

Other methods, such as dehumidifiers and insulation panels, can even cause more extensive damage. Dehumidifiers tend to draw additional moisture into the basement, while insulation panels fixed to interior walls can trap water leaking in from the outside, leading to mould between the insulation panel and the block wall.


Subsoil drainage is the most effective, permanent basement waterproofing solution. The sooner you install subsoil drainage, the less chance there is of widespread damage occurring, protecting your home and saving you money in the long run.

Ready to fix your damp basement or garage with subsoil drainage? Get in touch below for a no-obligation quote.

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