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How to repair a drain under a concrete slab

How to repair a drain under a concrete slab

Warning signs which could be an indication of water leaking from drains located under the slab foundation of your home.

  • wet spots
  • cracking
  • damp sections continually showing in the slab, carpet, or flooring even during periods of little or no rain, or mains water leakages.
  • chunks of concrete breaking away from the main slab
How to repair a drain under a concrete slab

Constant water seeping up into concrete foundations can seriously affect the structure of your building in the long term. To prevent major damages repairs should be carried out sooner rather than later. However, due to the hidden nature of the problem, drain leaks are often not detected until the issue has become significant.

Moisture from a leaking drain can permeate up into floor coverings, spoiling carpets or warping timber boards. It can also encourage mould and mildew growth inside walls, cause swelling of plasterboard, cabinets or render, and create cracks in floor tiles. In cases which have been left undiscovered or unrepaired for extended periods, water can also generate rotting in structural timber.

Concrete cancer risk

When water comes into contact with the steel in concrete slabs it can cause it to rust and expand, cracking the concrete surrounding the steel, and potentially affecting the structure of the slab. This is often referred to as concrete cancer and can sometimes induce spalling, or sections breaking away.

Drain rehabilitation options

Stopping concrete cancer and cracking needs to be the top priority for homeowners to prevent ongoing damage to the building. A CCTV plumbing inspection is useful to uncover the exact location of the leak allowing for targeted repairs to be carried out.

Homeowners a couple of options to consider.

One option requires cutting a trench in the slab, digging up the pipe and replacing the broken section of the drain pipe. This choice involves a certain amount of chaos. Cutting concrete creates huge quantities of dust and mess. The area will need to be sectioned off and protected with plastic sheeting to contain the debris.

A second option involves placing a new lining inside the cracked pipe to seal the leak and establish a strong, long-lasting inner layer, preventing wastewater escaping in the future. This alternative can be carried out, in most cases, without cutting the concrete.

Using pipe relining to repair a leaking drain under a concrete foundation or driveway has a few other advantages as well.

  • no digging or cutting
  • minimum disruption to your home
  • no lifting up and relaying carpet, tiles, or floorboards
  • if the CCTV drain inspection uncovers large areas of cracking inside the drain the fix is still as straightforward
  • immediate results - no waiting for new concrete to set and cure

If you suspect a drain is leaking under the concrete slab in your Brisbane or Gold Coast home contact our specialist drain repair team for a professional no-cut drain rehabilitation alternative.

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