How do you repair a drain under a concrete slab?

Having a drain that is blocked or needs repairing is disruptive enough, but what do you do if that drain is located under a concrete slab?

There are a few different options available, but it is always suggested that you call in the professionals to help. If you need further assistance, give Reline Solutions a call at 0403 355 550 and we can discuss your drainage needs.

Common signs of water leaks under concrete

There are a few warning signs to look out for when it comes to water leaking from drains located under the slab foundation of your home. These include:

• 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

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.

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.

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.

How do you repair a drain under a concrete slab?

So, how do you repair a drain under a concrete slab?

Stopping concrete cancer and cracking needs to be the top priority for homeowners to prevent ongoing damage to the building, and there are a few steps that should be taken.

Plumbing Inspection

A CCTV plumbing inspection is useful to uncover the exact location of the leak allowing for targeted repairs to be carried out.

Plumbing inspections will not only identify blockages but also whether the pipe has deteriorated in any areas which could lead to issues in the near future. Some of the specific problems a CCTV pipe inspection can identify are:

• Blocked drains.
• Cracked or broken drains.
• Tree root intrusion.
• Squashed pipes.
• Deterioration of pipes.
• Foreign objects causing blockages.
• A failed pipe-lining.

An inspection can also be used to accurately locate and map out drainage pipes throughout your property.

Cutting a trench

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.

Trenchless technology

If you do not wish to dig up your yard, there are other options available if you have a blocked drain. These include using either a water jetter or a robotic cutter to remove a blockage, both of which are gentle on plumbing and do not cause further issues, and then repairing the pipe.

More information about trenchless technology can be found here - What is trenchless technology ?

Pipe relining for damaged pipes under a concrete slab

A second option involves placing a new lining inside the cracked pipe under the concrete slab to seal the leak and establish a strong, long-lasting inner layer, preventing wastewater from 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.

Pipe patching

Another option is known as pipe patching , where a section of pipe is repaired with a patch made from fibreglass matting that has been impregnated with a specially formulated silicate resin.

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.