How to Put a Drain Through an Existing Concrete Slab

Updated February 21, 2017

One of the hardest projects when renovating a basement or a home is installing a new drain into a concrete floor. Although this task is difficult and labour intensive, it is not outside of the realm of possibility for a homeowner to complete on his own. It is important, however, to feel comfortable with the task; damage to the floor is likely to occur if the job is not done correctly.

Place a chalk string from the existing drain in the home to a couple of inches beyond where the new drain is to be installed. Snap the chalk line to create a visible mark. Move over approximately 12 inches and snap a second line.

Cut the concrete with a circular saw equipped with a masonry blade. If a saw is not available, walk-behind saws are available for rent at most home improvement stores. Cut two grooves into the floor, one on each chalk line.

Bust up the concrete between both cuts with a chisel and a sledgehammer. Remove the concrete from the floor and place it off to the side.

Excavate the gravel and dirt from the ditch with a shovel. Start at the new drain location and work back toward the existing pipe. Create a slight pitch; the new drain is to flow downward into the drain pipe to ensure the water does not sit in the new pipe.

Place the T-junction against the existing pipe and mark the ends of the junction onto the pipe. Cut the section of pipe out with a saw or with a cast iron pipe cutter, depending on the type of drain pipe that is present.

Coat each end of the T-junction with PVC glue and slide the rubber boots onto the ends. Slide the rubber boots onto the existing pipe and tighten the clamps on the boots with a screwdriver.

Cut a piece of drainpipe to match the length needed to reach between the T-junction now attached to the old pipe and between the location where the new drain is desired.

Coat the ends of the pipe with PVC glue and then slide the pipe into the T-junction.

Coat the other end of the pipe with PVC glue and then coat the inside of a 90-degree PVC elbow with PVC glue. Slide the elbow onto the pipe.

Cut a piece of pipe that is to extend from the elbow and allow the drain to sit level with the concrete floor. Attach the piece of pie to the elbow with PVC glue.

Attach the drain onto the end of the PVC pipe. This process differs slightly depending on what type of drain you purchased. Follow the directions supplied with the drain.

Fill the hole with gravel until it is level with the bottom of the concrete. Tamp the gravel down with to ensure the gravel is firm under the pipe.

Fill the remainder of the hole with cement and level it with the rest of the floor with a cement trowel.

Things You'll Need

  • Chalk string
  • Circular saw
  • Masonry saw blade
  • Shovel
  • Saw or cast iron cutter
  • T-Junction
  • Rubber coupler boots
  • Screwdriver
  • PVC pipe
  • PVC glue
  • PVC elbow
  • Drain
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