Drain and Vent / Half bathroom
Half bath, sink across from the toilet: air admittance valves, wood floor
A toilet on one wall and a small sink on the wall across, the usual powder room under a stair. Air admittance valves vent the fixtures; check your city allows them. The floor is wood framing over a crawlspace, basement or room below: the drains run between or through the joists.
What is on your rough-in sheet
Three Letter pages for this room (toilet, bathroom sink), drawn for a wood floor. Print them and tape them to a stud.
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.
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.
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
- Pull the permit. Most places need one for new drains and vents, and the inspector sees the rough-in before the walls close.
- 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.
- Shut the water off before you cut into a supply line, and open a faucet below to drain it.
- Check the joists. On a wood floor, a drain across the joists means bored holes, and holes have size limits.
For this room
-
This room
Oatey 43613 closet flange, 3 or 4 in PVC, stainless ring Glues into the 3 in closet bend, or over 4 in, with a stainless ring that will not rust. Check the current price -
This room
Oatey Sure-Vent air admittance valve, 1-1/2 to 2 in The AAV the sheet places, with its PVC adapter. Rated 160 DFU on a branch. Check the current price -
Every rough-in
SharkBite 1/2 in crimp x 3/8 in straight stop, quarter turn Quarter-turn stop for each supply stub-out. Check the current price -
Every rough-in
Cherne 270032 Test-Ball plug, 3 in Plugs the drain so the system can be filled with water for the rough-in test. Check the current price -
Every rough-in
KF CPTEC PEX crimp tool, 1/2 and 3/4 in Copper-ring crimper for the PEX supply lines to every fixture. Check the current price -
Every rough-in
Oatey purple PVC primer, 8800 series The purple ring the inspector looks for on every joint. Check the current price
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