Pipes should never be installed horizontally through a concrete slab on the floor. All pipes run beneath the slab supports in the floor. The lines then “go” vertically through the slab to allow subsequent connections to be made. The process for installing pipes in a concrete slab is physically demanding and you must be mechanically precise. You must install the pipe to the exact specifications as detailed in the construction drawings.
- Mark the place where you have to dig to place the pipe using a measuring tape and spray paint. Pay close attention to the measurements shown in the drawings of your building; work on the location of each line below the concrete slab. Mark existing pipe lines with a line of spray paint and mark the spot where the pipe will slab with an “X” placed in a circle. Place this mark a few feet from the line that marks where the existing pipe is so you do not miss the mark when you dig the trench.
- For excavating the pipe trenches, depending on the length of the slab and the required placement depth, you may want to use a mechanical digger instead of a hand shovel. Make sure you meet all applicable OSHA regulations for digging a trench safely.
- Install the pipe and all connections in the trenches you have made, making sure the pipe rests on the pipe supports specified in the drawings of your building. Provide a vertical connection in places where every pipe must pass through the slab. Make these tubes long enough to extend a minimum of 6 inches (15.23 cm) above the top of the concrete slab.
- Cover the mouths of all outputs with tape to prevent debris from entering the pipe. Concrete debris or dirt entering the line can form a blockage in the pipe that you will not notice until the pipe is connected. By then, you’ll have to break the concrete to access the pipes to determine where the blockage is.
- Using a hand shovel or excavator to fill (cover with soil) the pipe lines, completely fill the trench so that the backfill is level with the floor of the lower area of the slab.
Tips & Warnings
- Spray paint pipes of plumbing lines so they can be easily seen by anyone working in the area of the slab. The tubes that cannot be seen often break before the area of the slab is poured with concrete by machines and workers.
- Use appropriate safety equipment when installing any type of pipe. This includes shoes, belts and back support. Even if you’re working with PVC pipe, the weight can damage your back or crush your feet if they are not properly protected.