Commercial Remodel Plumbing

Turning a retail space into food service is the biggest jump in this category. A shell that was fine for a clothing store has a small waste line and a small water heater, and a kitchen needs grease waste, floor sinks to take indirect waste from ice machines and prep sinks, hand sinks where the drawings put them, a mop basin, and far more hot water than the space was built for.

A restaurant becoming a different restaurant is easier, but rarely clean. The last tenant's interceptor may be undersized for the new menu, the new equipment layout moves the floor sinks, and the under-slab piping is often full of grease. Running a camera through the existing waste line before the layout is final costs an hour and it regularly changes what the layout should be.

Restroom work is where accessibility requirements bite, because the fixtures have to land in specific places instead of wherever the old ones sat. The water closet has a required distance from the side wall and a clear floor space around it, which partitions and, with limited exceptions, door swings have to stay out of, the lavatory needs knee clearance underneath with the trap and hot water piping protected, grab bars need solid backing in the wall, and the flush control has to be on the open side of the fixture.

In practice that means the toilet drain usually has to move, which on a slab means cutting concrete. Converting two cramped single-user restrooms into one accessible restroom, or rebuilding a two-stall restroom so one stall meets the requirements, are both common scopes. The dimensions come from the approved drawings for the project, and the inspector checks them at trim-out with a tape measure.

As-built drawings for a twenty-year-old building rarely match what is actually in the ground, so existing conditions get verified rather than trusted. A camera down the sanitary line shows the material, standing water that points to a slope problem, and the cracks, scale, and separated joints that mean a cast iron line under the slab is failing. Adding fixtures also means checking the water side, because meter size, static pressure, pressure under flow, and the size of the riser feeding the space all cap how many fixtures the space can carry before the service has to be upsized.

Water heating is the other ceiling. A unit sized for two lavatories will not serve a new kitchen or a bank of showers, and whether there is electrical or gas capacity for a larger unit is a question for the general contractor before the plumbing scope is priced. Finding these limits while the drawings are still being marked up is a design decision. Finding them in the middle of demolition is a delay.

Any drain, waste, and vent piping that gets altered has to be tested before it is closed in. The altered section is capped and filled so it holds a standing column of water for the hydrostatic plumbing test, and new water piping goes under a plumbing pressure test that has to hold while the joints are checked. In a commercial ceiling that means the inspection happens before the grid and tile go back up, not after.

The phases are the same as new construction, just compressed: underground while the slab is open, rough-in or top-out before walls and ceilings close, and trim-out once the fixtures are set. Grease interceptors and any backflow assembly are tested and the results documented for the utility. On a food service space the health department review runs on its own track alongside the building inspection. Test method and duration come from the building department with jurisdiction over that address.

Most of this work happens outside business hours. Cutting a slab, shutting the water down, and taking a restroom out of service are scheduled for nights, early mornings, or a closed day, and the neighboring tenants are told before it happens rather than after.

What that asks of the customer is access and a decision maker. Keys or badges, an after-hours contact for the alarm, a route for material that does not run through the dining room, and somebody who can approve a change at two in the morning without waiting for a meeting. Where a restroom or a kitchen has to stay usable throughout, the work gets split into phases so one side is always in service. That takes longer overall and costs more, and it keeps the business open.