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Kitchen Remodel Cost Calculator

Drain relocation

Can the sink actually move, and what happens to the budget if it cannot

Moving the sink can turn a predictable job into an open-ended one. Moving a sink is not moving a faucet. The waste line has to fall continuously all the way to where it meets the existing stack, and a floor only has so much depth to give it.

Can the drain physically get there

The move
ft

Pick the fall your inspector enforces from the three values offered; the page opens on one quarter inch per foot as an example, not as a code value. A fall outside these three cannot be entered here.

The floor structure
in

Measure your joist rather than going by its nominal size. Engineered joists vary; read the label on the web.

in
in

Sleepers, a mud bed, or a raised subfloor can add room here; a bare subfloor adds little.

What else moves with it

Derived feasibility

Not inside this floor

The drain needs 5.13 inches of vertical room and the floor offers 4.58. It is short by 0.54 inches, so this move cannot be made inside the existing floor at 0.25 inch per foot.

Fall the move requires 2.75 in distance times your slope
Total depth needed 5.13 in fall plus pipe diameter
Depth the floor offers 4.58 in
Margin -0.54 in
Furthest it can travel 8.8 ft inside this floor, at this slope
Usable joist depth 3.08 in

Trades this move brings in Plumber

  • At this slope the furthest the trap can travel inside the floor is about 8.8 feet. Shortening the move to that distance avoids the alternatives below.
  • With a crawlspace or open space below, the line can run below the joists; with a finished ceiling below it means a soffit or a ceiling repair. Sistered or engineered joists and a sewage ejector are the other options, and each is a larger job than the sink.
  • The vent has to move with the fixture. Re-venting adds plumbing time, because the vent has to reach a stack or the roof and has its own routing rules.
  • Running across the joists means boring each joist in the path; this tool assumes only one third of the joist depth is usable for that, which is our own simplification, not a code figure.

The arithmetic, in full

  1. Required fall. The trap moves 11 feet and the line must drop 0.25 inches for each foot it travels, so it needs 2.75 inches of vertical drop end to end.
  2. Depth the pipe occupies. Add the outside diameter of the pipe and its fittings, 2.375 inches, giving 5.13 inches of vertical space the floor has to contain.
  3. Depth the floor offers. Running across joists, this tool counts one third of the joist depth as usable (our own simplification, not a code figure). That gives 3.08 inches, plus 1.50 inches of build-up above the joists, for 4.58 inches.
  4. The margin. 4.58 minus 5.13 is -0.54 inches (worked from the unrounded depths). Positive means it fits. Negative means the move, at this slope, does not happen inside this floor.
  5. The useful inversion. Rearranged, the furthest the trap can travel and still fit is 8.8 feet. That number is worth more than the verdict, because it tells you where to put the sink instead.

What actually costs money when the answer is no

Opening a ceiling below

If the room underneath is finished, the drain route runs through somebody's living room ceiling. The plumbing itself might be a day. The ceiling repair, the texture match, the paint and the fact that the room has to be emptied are all separate line items in a room that was never part of the remodel.

Cutting a slab

On grade there is no cavity at all, so the line goes below the concrete. That means saw-cutting a trench the length of the run, breaking out and removing the spoil, laying and inspecting the new line while the trench is open, then filling, patching and levelling before any floor goes down. If your inspector needs to see the trench open, that is an inspection hold in the middle of the schedule.

A sewage ejector

Where gravity genuinely cannot be achieved, a pump can move waste uphill. It solves the geometry and introduces a mechanical device with a service life, a power requirement and a failure mode under a kitchen floor. It is a real option and it should be a last one.

Or: move the sink less far

Shortening the move can be the cheapest fix. At 8.8 feet or less this drain stays inside the existing floor and the work above is not needed. A sink two feet from where you wanted it, in a kitchen that came in on budget, is a trade worth weighing before demolition.

What to do with this answer