Full Answer
What is a “dirty arm”?
The section of the code that pertains to the maximum trap-arm (also called a “dirty arm”) length has strict provisions designed to prevent a siphon from forming in a drain. For simplicity, the maximum distance between a trap and its protecting vent has been presented in the form of a table for decades.
Do most plumbers Dirty arm the sink?
Most plumbers in my area dirty arm the sink now. It's always under a window, and it's hard to get your vent up to 42" before having to go horizontal. So instead of coming up on center, they come up within 42" and use a 2x1-1/2x2 tee. Re: Dirty Arm or Revent?
How do I replace a dirty arm on a bathroom wall?
You would need to open the wall cut the drain/vent and move the sanitary tee down and then drill new holes in the studs for the dirty arm. Or possible turn the san tee so it comes straight out of the wall and then plumb to it without messing with studs.
How far can I run a toilet on the Dirty arm?
in mass, you can go 60" on the dirty arm and still pass code. so, 42" should be fine. however, the 10ft measurement for the toilet exceeds the maximum distance from the stack. as a general rule of thumb, 2 times the size of pipe plus 2. so,(for 1 1/2 pipe) 1 1/2 times 2 equals 3. plus 2 equals 5ft.
What is a waste trap arm?
The trap arm is the portion of a fixture drain between a trap weir and its protecting vent. The trap weir is the point at the bottom of the trap arm pipe where it connects to the trap.
How many degrees is a trap arm?
vent must not exceed 135 degrees except for a water closet trap arm which cannot exceed 225 degrees.
How long can a toilet arm be?
If you're in the IPC, there is no limitation in length for the toilet's trap arm. That's right, no limitation! That means your fixture drain can have an unlimited distance (909.1). Keep in mind your toilet still needs a vent, but your trap arm can be as long as necessary.
How far can you run a drain without a vent?
If you have 1- 1/4-inch pipe, the horizontal distance of the vent ought to not be more than 30 inches. For a 1- 1/2-inc pipe the vent must be 42 inches away at the most while a 2-inch pipeline must have an optimum distance of 5 feet.
Can you use a 90 on a trap arm?
6.3 says this would not be allowed: (c) the trap arm does not have a cumulative change in direction of more than 135°. 90+90 = 180°, so that's too much.
What is the minimum length of a trap arm?
The minimum trap arm length is two pipe diameters, as measured from the trap weir to the vent (not between the hubs of the fittings). So a 2” pipe would require a 4” trap arm minimum.
Can a toilet and shower share the same drain?
The general answer is that the showers and toilets can use the same drain, but they should not be sharing the same waste trap arm. There are other factors to consider as well, such as whether your drains lead to the main sewer line, or if there are septic tanks that are used in your city or town.
What happens if a toilet is not vented?
Poorly-vented drain lines will not be able to effectively move wastewater and solid waste out of your building. This could lead to problems such as overflowing drains, backed-up toilets, and similar plumbing issues.
Can a shower and toilet share a vent?
Wet vents are typically used when plumbing a bathroom group. So yes the shower can also be vented by the wet vent along with the toilet. There is one major stipulation when wet venting multiple fixtures when a toilet is one of them: the toilet must be the last fixture connected to the wet vent.
Do plumbing vents have to go through the roof?
It does not have to go through the roof. From the plumbing code (I have the 2003 edition), P3103: It must not be less than 4 feet directly beneath a door, openable window or other air intake of the building or adjacent building.
Can a vent pipe have an elbow?
Note: You may have vent piping, but you still cannot use the tight 90-degree elbow -- sometimes called a "vent elbow" -- if the joint is below the water level, which is usually at the level of the sink.
How many fixtures can a 2 inch vent handle?
The Plumbing Code states that a vent can handle 24 fixture units. A bathroom sink of 1.0 F.U., a bathtub of 2.0 F.U., and a shower of 2.0 F.U.
Trouble with Tables
More Than The Minimum Slope
- But the slope column is saying much more than that. It’s stating that you can only use up toan 8-foot length if the pipe is run at the minimum allowable slope of 1/4 inch per foot. But often, installers don’t install pipe at the minimum slope, just as they wouldn’t stand at the very edge of a cliff to enjoy the vista. (For many code applications, I use that analogy to encourage people to b…
Keep The Vent Connection Above The Trap Weir
- When I’m performing a plumbing inspection, I don’t often bother with measuring the exact drain length, unless it seems to be unusually long or is clearly at a shallow slope. With the siphon principle in mind, I first make sure that any drain less than 3 inches in diameter has at least a 1/4-inch slope (1/8-inch slope for 3-inch diameter and greater), and then I simply measure from the f…