HELP & GUIDES

Plumbing

What it's for

A rough-in takeoff from a fixture count. Set how many of each fixture the house has and you get the total drainage fixture units, a main drain size, a fittings estimate, a riser drawing, and a material list of drain, supply and vent pipe. It is an estimate for pricing and ordering. Nothing on the results card passes or fails, and it does not lay out or size the branches.

Step by step

The example is the screen as it opens: one of each fixture, two hose bibbs, two stories, 60' 0" from the main to the farthest fixture.

Plumbing inputs: FIXTURES with TOILET 1, BATHROOM SINK 1, KITCHEN SINK 1, BATHTUB 1, SHOWER 1, WASHER 1, DISHWASHER 1, UTILITY SINK 1, HOSE BIBB 2, then STORIES 2, MAIN TO FARTHEST FIXTURE 60' 0", MAIN SUPPLY SIZE 3/4, and WASTE FACTOR 10% on the bottom edge. 16 DFU is pinned under the title. 1 2 3 4
Steps 1–4. Step 1 is the whole FIXTURES list, one − + row per fixture.
  1. Under FIXTURES, set the count of each with − and +: TOILET, BATHROOM SINK, KITCHEN SINK, BATHTUB, SHOWER, WASHER, DISHWASHER, UTILITY SINK and HOSE BIBB. The list is fixed. Set a fixture to 0 if the job has none.
  2. STORIES — how many floors have plumbing. It multiplies the supply pipe run and nothing else. The example is 2.
  3. MAIN TO FARTHEST FIXTURE — the pipe route from where the main comes in to the fixture farthest from it, measured the way the pipe will run. The example is 60' 0".
  4. MAIN SUPPLY SIZE — 1/2, 3/4, 1, 1 1/4 or 1 1/2. It names the supply pipe row in MATERIALS. It does not change any number. The example is 3/4.
  5. WASTE FACTOR — extra pipe and fittings, in steps of 5%. The example is 10%.
  6. Read RESULTS: 16 DFU, 3 in main drain, 33 fittings estimated.
  7. Tap BASIS & WHAT WAS ASSUMED to see which code tables the fixture units and the drain size come from.
  8. Scroll down to the riser drawing.
  9. Read MATERIALS for the order.

Reading the results

Plumbing results: 16 DFU, 3 in main drain, 33 fittings estimated, the BASIS & WHAT WAS ASSUMED row, then a DWV riser drawing with a branch for each fixture labelled with its DFU and a running total, from 1 WC 3 DFU Σ3 to 1 US 2 DFU Σ16, 2 HB 0 DFU · NO DWV dashed, a 3 IN drain to SEWER dimensioned 60' 0", and notes including FALL 1' 3" @ 1/4"/FT UPC · 7-1/2" @ 1/8"/FT IPC. 6 7 8
Steps 6–8: the counts, the basis row, the riser.
Plumbing materials: Main drain 3 in — 3 in min with any WC; 4 in over 3 WCs (UPC — IPC branches cap at 2) — verify local code 66 lin ft, Supply pipe 3/4 132 lin ft, Assorted fittings 33 pcs, Vent pipe (1-1/2 – 2 in) — rough proxy — verify vent layout per code 45 lin ft, then a dimmed SHARE PDF with a list icon at its right end, beside a lit SAVE. 9
Step 9: the order, with waste added.

The headline is the total drainage fixture units: each fixture's count times its unit value, added up. A hose bibb has no drain, so it adds nothing. The drawing shows every fixture's value and the running total, from 1 WC 3 DFU Σ3 to 1 US 2 DFU Σ16 in the example.

The main drain line is the size picked for the building drain from the total and from how many toilets there are. The first note under the drawing says why. In the example: 16 DFU · 1 WC · DRAIN 3 IN — OVER 6 DFU. With no fixture that drains, the line reads supply only — no DWV and the drain and vent rows leave the material list.

Fittings estimated is a rule of thumb, a few fittings for every fixture, with waste added. Treat it as a starting count.

BASIS & WHAT WAS ASSUMED opens to one line naming the IPC tables the fixture units and the drain size are taken from, and the value used for a washer standpipe. If you work to a different code, check your own table.

The drawing is a schematic riser: the stack with its vent through the roof (VTR), a branch for each fixture, and the building drain running to the sewer with your run dimensioned. The fixture tags are WC toilet, LAV bathroom sink, KS kitchen sink, TUB, SH shower, WM washer, DW dishwasher, US utility sink and HB hose bibb. The engine does not work out slope. With a 3 in or 4 in drain the drawing prints the fall over your run twice, once for each model code, and labels them (with a 2 in drain both codes agree and it prints one fall): FALL 1' 3" @ 1/4"/FT UPC · 7-1/2" @ 1/8"/FT IPC in the example. Two notes say the riser is schematic, not isometric, and that the branches are not arranged by story. Only the total at the base is a calculated figure. Pinch to zoom, drag to move around, double-tap to reset, or tap the expand button at its top right for the whole screen. See Reading the drawing.

MATERIALS, with waste added and rounded up:

The buttons wait for your own numbers: SHARE PDF and the list icon in it stay dimmed, and a tap on SAVE only answers Enter your job's numbers first. After that SHARE PDF shares the riser, the counts, your fixtures and the materials, the list icon at the right end of the same button shares the material list alone, and SAVE puts the result in History. The PDF footer reads Estimate — verify dimensions and local code before cutting/ordering. Your local code and your inspector govern pipe sizes, slope and venting.

Plumbing is a Pro calculator. The PDF and History are Pro too. Pro is a one-time purchase. See Free and Pro.

Common mistakes