Drain and Vent

Drain and Vent / Full bathroom

Shower, toilet and sink, all on one wall: wet vent, wood floor

The shower, the toilet and the sink all back onto one stud wall, the classic 5 x 8 bathroom. One dry vent goes up from the sink; the shower and the toilet are vented through the sink's drain, which is allowed for fixtures in one bathroom and saves two vent pipes. The floor is wood framing over a crawlspace, basement or room below: the drains run between or through the joists.

Where the fixtures are
Tub or shower
Sinks
How it is vented
Floor

Get this room's rough-in sheet, $7

ShowerToiletBathroom sink
Your room as a display drawing. The pipe sizes, the vents, the falls and every rough-in height are on the sheet.

What is on your rough-in sheet

Three Letter pages for this room (shower, toilet, bathroom sink), drawn for a wood floor. Print them and tape them to a stud.

  1. Sheet 1

    The riser drawing

    Every drain and vent pipe drawn at its size, the vents dashed, the fall marked on every run, and where each fixture ties in.

  2. Sheet 2

    Plan and wall

    The floor plan with every drain located from the walls, and the plumbing wall with every stub-out, valve and shower head height.

  3. Sheet 3

    The counter list and the checks

    Every fitting by name and size, counted, to read out at the supply house. Each trap arm checked against its limit, and the test the inspector will ask for.

Checked before it is drawn

  • Every branch sized for the fixture units it carries (IRC Table P3005.4.1)
  • Every trap within its distance to a vent (Table P3105.1)
  • Wet vents sized and ordered as P3108 requires
  • Every fixture vented; AAVs placed as P3114 requires
  • Falls of 1/4 or 1/8 in per foot by pipe size (P3005.3)

Before you cut

  1. Pull the permit. Most places need one for new drains and vents, and the inspector sees the rough-in before the walls close.
  2. Find your code. This sheet follows the IRC. Many western states use the UPC, and some cities ban AAVs. A call to the building department settles it.
  3. Shut the water off before you cut into a supply line, and open a faucet below to drain it.
  4. Check the joists. On a wood floor, a drain across the joists means bored holes, and holes have size limits.

For this room

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