Questions about outdoor shower drain connected to main sewer

[hardroadz]

I am in Sacramento, CA area and am building an outdoor shower to be connected to main sewer. I have a couple of questions:

1.) Do I still need to install a P trap even though it is outdoors?

2.) Do I have to drop down immediately to 18", below ground, or can I start out a little higher and quickly slope down to that depth underground over 8ft or so? (I want to take advantage of that elevation and utilize it for the plumbing drop over distance, rather than "waste" some of that elevation by immediately dropping down to 18 inches. On another note, the 2 inch shower drain pipe will transition to 4 inch after about 6ft or so.

Any knowledge or insight on any of these will be much appreciated. Thanks, all!!~Robert

 

[ICE]

A P-trap is required. The CRC mentions a minimum depth of 12”. If you want to have less depth, place some concrete. A cleanout is required for the 2” and if the branch has 4” pipe it needs a 3.5” cleanout.

Be aware that rainwater is not allowed to enter the drain.

 

[hardroadz]

A P-trap is required. The CRC mentions a minimum depth of 12”. If you want to have less depth, place some concrete. A cleanout is required for the 2” and if the branch has 4” pipe it needs a 3.5” cleanout.

Be aware that rainwater is not allowed to enter the drain.

How fast does it need to get to that 12" depth? does it have to start that way straight down from the drain, or can it get there over 6 ft or so?

 

[hardroadz]

How fast does it need to get to that 12" depth? does it have to start that way straight down from the drain, or can it get there over 6 ft or so?

ICE, thank you so much for the info. I am indebted. I did some research and found that it needs to drop down to the 12" depth straight from the drain, so I think I answered my own question.

One follow-up question: Is that 12" depth the depth of the trench or the depth from the top of the pipe? This would make about 2.5" difference for 2 inch pipe and obviously much more for 4" pipe.

 

[ICE]

How fast does it need to get to that 12" depth? does it have to start that way straight down from the drain, or can it get there over 6 ft or so?

Because the waste pipe will be buried in a yard as opposed to under a structure it is required to adhere to code as it applies to a building sewer. The following is the code that is often applied to require a building sewer to be 12" below grade. As far as I can tell, this is the only time the burial depth of sewer pipe is mentioned in the code.

312.3 Building Sewer and Drainage Piping. No building sewer or other drainage piping or part thereof, constructed of materials other than those approved for use under or within a building, shall be installed under or within 2 feet (610 mm) of a building or structure, or less than 1 foot (305 mm) below the surface of the ground.

718.3 Protection from Damage. No building sewer or other drainage piping or part thereof, which is constructed of mate- rials other than those approved for use under or within a building, shall be installed under or within 2 feet (610 mm) of a building or structure, or part thereof, nor less than 1 foot (305 mm) below the surface of the ground. The provisions of this subsection include structures such as porches and steps, whether covered or uncovered; breezeways; roofed porte cocheres; roofed patios; carports; covered walks; covered driveways; and similar structures or appurtenances.

The code sections do not apply to ABS pipe in that ABS is allowed under or within a building. The same goes for PVC and cast iron. What the section does apply to is clay sewer pipe. However, anytime I hear an inspector state a minimum depth for sewer pipe I am convinced that it is a reference to 312.3. That is why I told you to 12". Force of a bad habit. My apology for taking the easy way.

I have seen a correction that required the under-slab waste pipe to be lowered to meet the 12" depth...often. Many inspectors are convinced that a building drain shall be a minimum 12" below grade where it exits the building. I used to be equally deluded.

If you are getting a permit it would be a good idea to ask the local inspector about the depth of burial. If he provides a number it will most likely be easier to accept that number than trying to convince him otherwise. Trust me on that...I have tried and failed.

Measure to the top of the pipe.

 

[hardroadz]

Thank you for that. 2 final questions:

1.) Can I use 2x6" as my floor joists for the shower structure? (Note: Structure is 56" x 72" x 8' H)
2.) Can I use Trex composite decking as my flooring?

Thank you!~Robert