Skip to main content

How Deep Are Plumbing Pipes Under A Slab House

slab of a house

When you are building your custom home or renovating your current home with an expansion, always remember that building codes must be followed. The local building codes are put in place to hold contractors accountable and protect the homeowner’s investment. In the early stages of building, make sure to inspect the plumbing pipe installation. Homeowners like to walk their lot with new construction and evaluate the progress. Feel free to bring a measuring tape or your local home inspection team to ensure proper installation has been completed. How deep are plumbing pipes under a slab house? Typically, a 12 to 24 inch depth of your plumbing pipes under a concrete slab house.

Let’s take a look below at some more specifics and understand why various depths are important.

What Is A Slab Foundation

A slab foundation is currently the cheapest and easiest installation for a contractor. The majority of new homes are constructed on a flat poured concrete surface. Inside the concrete pour, you have many rebars and mesh wiring that keeps the concrete intact. Also, due to this added metal inside the concrete, it can support the weight of all of the walls of the home.

Exposed buried pipe in between the rebar before a concrete slab is poured.
Rebar before a concrete pour.

What Determines My Plumbing Depth

There are a few areas to keep in mind when understanding how deep are plumbing pipes under a slab house foundation. Typically, the depths will vary based on where you live. Let’s take a look at the main reasons for certain plumbing depths under a concrete slab.

  • Building Code – making sure that your local contractor understands the local building code is key. You want to ensure that the codes for plumbing burial are followed. This will allow you to avoid expensive repair bills down the road.
  • Frost Line – the colder the climate that you live in, the deeper your frost line will be. Living in Florida will have a lower frost line, so the depths to bury your plumbing will be less than an area where freezing temperatures are more prevalent.
  • Current Set up – the way your land is setup can often determine how deep your plumbing pipes will need to go. The housing plans will often dictate what the contractor needs to do for your plumbing system to be buried correctly.

How Deep Does My Plumbing Run Under A Slab

Believe it or not, plumbing pipes under a slab house foundation is typically 12 to 24 inches deep. The pipes are installed into trenches and then buried before the rebar, wire mesh, and concrete slab are poured. The weight of the home is supported by the concrete slab, so no pressure is placed on the plumbing pipes which can create plumbing problems.

The pipes installed are water pipes, drain pipes, and public sewer pipes. You might also see a septic tank pipe system that runs away from the home. Also, the pipes are installed at a gradual angle and gravity flow pushes all waste to the street sewer system.

Why Do I Need To Bury My Plumbing Under A Slab

Typically, you bury your plumbing pipes under a slab foundation for a few reasons. Functionality and aesthetics are the main reasons for burying your plumbing. The slab foundation acts as an insulator and attempts to protect the pipes from freezing and bursting. Keep in mind that in some cases the pipes could freeze and or burst.

Also, since you have a sewer line and a water line, the slab foundation will keep foul smells and strange odors from coming into the home. Lastly, the slab foundation protects the pipes from physical damage. An example is weight bearing crushing, which could lead to major repairs and flooding.

Other Recommended Maintenance

While you are thinking about how deep the plumbing pipes are under the slab of the house, there are also other things to things to think about.

The first thing is when to walk away from foundation issues. If your home is finished and you notice issues in the home such as doors and windows are not level, or cracking on the walls and flooring inside and outside the home you may have foundation issues. You may want to contact a home inspection company before you close on the home to have it fixed. Additionally, you will want to know how much it will cost to be fixed.

Another area to think about is soil. It will be important to know how much soil you need to build up around the house. To know this, think about is determining the slope, building up the slope gradient, filling in excess areas, and checking for consistency.

Lastly, if you live on the coast and are thinking about installing a seawall, it is a great idea! A seawall will mitigate flood damage and there are different types to choose from. The last thing you want to do is risk flooding of your beautiful home so a seawall is a perfect answer.

Inspecting a slab to make sure the pipes are deep enough is important.

When Do I Call A Professional

When it comes to plumbing depths under your concrete slab foundation, you will wan to defer to a professional contractor. Whether you are building a new home or renovating an existing home, the professional contractor is responsible for knowing all of the building codes in your local area. If you aren’t sure who the best local contractor is, call on your local home inspection team to get a referral. Also, they can inspect your current foundation and inform you of any other issues.


If you really aren’t sure what to do, trust your local licensed structural engineer, home inspection team, and licensed general contractor. All three of these professionals can work together to ensure that the needed depth for your plumbing to be buried under the slab foundation is followed.

After all, three minds are better than one. If a depth is not followed at the time of inspection, this can be fixed before any concrete is poured.

Call Waypoint Property Inspection to inspect your home in Tampa, St. Petersburg, Lakeland, Orlando, Palm Beach, Ft. Lauderdale, and surrounding areas.