Code Applied by the app plumb.trap.seal
Trap seal depth and protection
Every fixture trap holds a water seal 2 to 4 inches deep, and a trap that can dry out, a floor drain that sees no water for months, gets seal protection such as a trap primer.
| When | The app uses |
|---|---|
| trap seal depth, at least | 2 in |
| trap seal depth, at most | 4 in |
| an emergency floor drain, or a trap subject to evaporation | seal protection (a trap primer or a barrier device) |
- Source
- IPC · 1002.4 Trap seals, 1002.4.1 Trap seal protection · read the public text
- Editions checked
- 2018 · 2021
- Used by
- Courses
- Amendments
No state or local amendment to this rule is on file. Not on file means the model code as written — check your jurisdiction.
A model code the authority having jurisdiction adopts.
A trap is a bend that holds water, and the water is what keeps sewer gas in the pipe. A drain that sees no water for months, a floor drain in a restroom or a storage room, loses its seal to evaporation, and the room starts to smell of sewer. The code asks for seal protection on those traps. The course teaches the common one: a trap primer, a valve on a cold line that drips a little water into the trap.
On a bid the primer is a valve, a small line to each drain it serves and the labor to set it, and the plan rarely draws any of it. A keynote such as FLOOR DRAIN W/ TRAP PRIMER, TYP. means one per floor drain.
What the app does with it
Nothing yet: the app does not apply this rule. It is on a course card (the plumbing course, Chapter 2, "What the FD keynote costs"), which has you add a Trap primer row, 1 per count, under the floor drain counter's Child counts, so the primers ride the drains you click. The app does not add that row for you.
Verify against your edition
The code lists several ways to protect a seal besides a primer valve (a primer fed by waste water, a barrier-type device); which one the engineer means is on the plumbing schedule or the keynote. Some jurisdictions require a primer on every floor drain whatever its use. The Uniform Plumbing Code sets the same seal depth and asks for a primer on a floor drain that sees little use (1005.1 and 1007.1 in the 2018 edition). Settled 2026-09-27 by Claude on the owner's delegation, from the dossier's research and the model code text; not checked against a printed book or a local amendment.
Cited by section, not reprinted: the code text belongs to its publisher. Company practice is not a rule here — it lives with your pricing.