Drains and pipes for plumbing are usually installed during construction and before the concrete is poured for the building foundations.

This means that a majority of the plumbing connections are inside the foundations.

So when you need to fix or replace a broken toilet drain or if you are installing a new one, it will be necessary to cut through the concrete foundation.

Cutting a concrete slab needs careful preparation and planning. If plumbing lines are housed inside the foundation, it is possible that other utility lines are there too.

Pre-Cutting Preparations

Before you start cutting, make sure you check for the following:

  • Determine the location of the existing plumbing system
  • If the home has in-floor heating, locate the coils to avoid damaging the whole system
  • Locate conduits and electrical lines
  • Get a copy of your home’s mechanical plans

Mechanical plans are filed in your local registry so if you do not have a copy, you can easily request for one from your local authority.

What You Will Need

Most concrete foundations in residential buildings are four-inches thick with steel rebar and steel mesh for reinforcement.

Therefore, in order to access a drainpipe inside a concrete slab, the following equipment and tools will be required:

  • A walk-behind concrete wet saw or hand saw with a diamond blade
  • A small sledgehammer (or pneumatic hammer)
  • A narrow blade shovel
  • Chalk and tape measure
  • Personal Protective Equipment (PPE):
    Goggles or protective eyewear
    Steel-toed boots

Step 1 – Measure And Mark The Cut

Using the mechanical blueprint of your house, measure and mark the area where you will cut the concrete slab for the toilet drain. Make sure that you measure correctly and cut accurately.

It is highly recommended to consult a structural engineer to ensure the accuracy of the cuts and to avoid damaging the structural integrity of the concrete.

How Cut Toilet Drain Through Concrete Slab measure

Step 2 – Cut The Concrete

Set the depth of the diamond blade of your concrete wet saw to 4 ½ inches (for the common four-inch concrete slab foundation).

If your concrete foundation is thicker than four inches, set the depth of the diamond blade half an inch more than its thickness. Cut along the chalk lines to avoid damaging important utility systems.

Do not forget to wear your Personal Protective Equipment when cutting. Cutting through the concrete foundation takes time and energy depending on the thickness and the steel reinforcement used.

The more time you spend on cutting, the more exposed you are to health and safety risks. Protect yourself at all times.

Step 3 – Dig And Clean Up

After cutting the concrete slab, you will need to use your sledgehammer (or pneumatic hammer) to break concrete strips into chunks so you can remove the pieces.

Once you have removed the concrete, dig the remaining trench and remove any sand or soil.

Step 4 – Remove The Broken Drain And Install The New One

Make sure the water is shut off and then remove the broken drain pipe and install the new one.

If you are installing a completely new drain for a new toilet, connect the new drain to the current plumbing system. Secure the drain and pipes to avoid leaks.

How Cut Toilet Drain Through Concrete Slab sledgehammer

Step 5 – Seal The Concrete

Once you have put in the new toilet drain, seal the cut foundation with new concrete. Consult your structural engineer regarding the cement mixture to ensure that the strength matches the original concrete slab.

When it comes to broken plumbing, the need to cut concrete is unavoidable.

For adding new toilets or for any bathroom renovations, if possible, plan the location so that you can run the drain line outside the foundation and tie it into the main drain line in the yard.

Important Reminders:

  • Always consult your structural engineer before cutting concrete slabs especially foundation concrete.
  • Do not operate the concrete saw if you have no experience or prior knowledge in handling the equipment.
  • Always wear protective gear when operating the concrete saw or when you are near the operations.

Cutting concrete foundation slabs is not easy because it requires a walk-around concrete saw (depending on the size of the job).

This is quite a large and intimidating machine that needs experienced hands to operate. That’s why it is highly recommended to let the expert handle this type of job.

MEGA SAW has over 20 years of experience in concrete cutting services. We can get the job done quickly but safely.

We provide a wide range of concrete services designed to make your life easier. We also use top-of-the-line equipment that will ensure quality work and reliable service.

Don’t risk your health and safety. Avoid making more damage to your property too. Leave the work to the experts.

If you are looking for a specialist concrete cutting company who uses only the best practices to get the job done right, then please call us at Megasaw on 1300 920 419 or contact us through our website.