Plumbing under the slab and above it.

Underground plumbing comes first

In a slab building, every drain is set before the concrete: restroom lines, floor drains, floor sinks in a kitchen, the line to the grease interceptor and the sewer service out to the street. The lines are tested and inspected before they are buried, because the next time anyone sees them is when the slab is cut.

In a finish-out, that means saw-cutting a trench in the existing slab, laying the new lines and patching the concrete back, like the patched trenches in our photos.

Licensed plumbers and the city

Plumbing in Texas is licensed by the Texas State Board of Plumbing Examiners, and the plumbing permit is pulled under a licensed plumber. Cities inspect the underground, the rough-in in the walls and the final, and many require the backflow devices on a commercial water service to be tested by a registered tester.

Water service and sewer taps

A new building needs a water meter, a tap on the city main and a sewer connection, and in most cities those are their own fees and inspections apart from the building permit. Sizing the meter for the fixture count, and for a kitchen or irrigation if there is one, keeps the water bill and the pressure where they should be.

On a remodel, the question is usually the opposite: whether the existing meter and line are big enough for a new restaurant or extra restrooms. We check before the layout is final, because a bigger meter or a new tap can change the budget.

Restrooms, grease and gas

Restrooms are where plumbing and accessibility meet: clearances, grab bars, sink heights and drinking fountains are set by the accessibility standards as much as by the plumbing code.

Restaurants add grease interceptors and floor sinks, and kitchens, water heaters and rooftop units often need gas lines, which are pressure tested before the gas company sets the meter.