DrainZzzzz

[R.B.]

Another question. I need to know about shower drain and washing machine drain. Can I put a 2 inch double sanitary T and safely connect both drains without having the washing machine push water back into the shower.Also what size vent should I use 11/2 or 2 inch coming off the top?Also going to p-trap the washer.

Or should i just stack 2 different T's. It is a 2 inch line , becouse there are 2 different lines running to the septic tank. Toilet is on an old cast iron line by its self.I know i need to replace with pvc but it is really snug under the house to try and dig and lay new line. Thanks.

[LazyPup]

First of all let me put your mind at ease a bit. Cast iron pipe is perfectly suitable for all DWV applications so as long as it is not leaking there is no need to replace it with PVC.

A Back-to-back (Sanitary Cross) may not be used to connect back to back drains if one drain receives a powered discharge (Washing machine).

Both a shower stall and a washing machine standpipe are required to be 2".

Under the International Residential Code a 2" waste arm may be a maximum of 8' from the stack or vented horizontal drain line. (Uniform Plumbing Code 5')

Once the vent line is 6" above the highest flood level rim of the fixtures it serves it may be reduced to 1/2 the diameter of the line it serves, but may not be less than 1 1/4". In climates that are subject to outdoor freezing temperaturs in winter all vents must be enlarged to 3" at least 1' inside the attic space before passing through the roof. (Some local codes require 4")

Under the International Residential Code the vent may be terminated by means of an air inlet valve (Studor vent), in the attic space, through the wall, or through the roof.

Under the Uniform Pluming Code all vents must terminate through the roof.

Under the Uniform Plumbing Code the washing machine standpipe P-trap may not be below the floor.
The P-trap must be a minimum of 6" but not more than 18" above the floor.
The inlet of the Standpipe must be a minimum of 18" but not more than 30" above the trap.

The International Residential code allows the trap to be under the floor but the inlet must be a minimum of 18" and not more than 42" above the trap.

[R.B.]

Ok, Just one thing that does'nt seem to add up on my equipment. The thread's on my tub/shower are 1 1/2. Why would they put them on if it's supposed to be 2 inch?

[LazyPup]

Excuse me,,,i misunderstood..I thought you were installing a shower stall which is 2".. a tub/shower is 1 1/2".

Under the international residential code the maximum length of the 1 1/2 tub/shower waste arm is 6' (Uniform plumbing code is 3' 6")

There is an exception in the code that says the waste arm line may be one nominal pipe size larger than the trap. The tub/shower requires a 1 1/2" trap, therefore if you can not make the run with the 1 1/2" length limits you can increase the line size after the trap to 2" and use the 2" length limits.

Also,,,if the tub/shower waste and overflow will be accessible from underneath or through an adjacent wall you may use the conventional slip joint type waste & overflow kit. If the tub/shower is over a finished ceiling or where you cannot make a service access panel you must use a glue in type waste & Overflow kit (slip joints may not be used in a concealed location)

[kactuskid]

quote:Under the International Residential Code the vent may be terminated by means of an air inlet valve (Studor vent), in the attic space, through the wall, or through the roof.

I was under the impression that an air admittance valve could be terminated locally at the fixture. I've seen lots of them, especially for sinks that are mounted under the sink but above the waste pipe. Also seen them used for venting basement bathrooms when a vent pipe couldn't be run up through the roof. Isn't this proper?

[LazyPup]

The International Residential Code allows the use of air admittance valves at the fixture location, but the Uniform Plumbing Code only allows a maximum of One air admittance valve per structure and then only with written approval of the inspecting authority. Normally they only permit an air admittance valve to create a vent for an island sink.

When attached at the fixture the air admittance valve must be a minimum of 4" above the waste arm connection to the vertical riser.

[R.B.]

Sorry my mistake in trying to explain my situation. I beleive LazyPup has answered my question.

I have a shower/tub on one side of the wall and a washing machine on the back side. I was trying to find a way to pipe the drains.

I beleive the only way i can achive this is to come off the tub with P trap into a 2" sanitary T with a reducer bushing for the 1 1/2 tub drain. Then place another 2" Sanitary tee on top of that for the washing machine drain. Then bring my vent off the top of that tee and tie into the existing vent threw the roof.

Please let me know if this will work. This house was built in the early 60's and trying not to do a demolition project.
Just went threw a rewire job, what a headache that was. Lots of sheetrock patching.

Thanks..I will also have access to the plumbing connections.

[LazyPup]

INFORMATION BASED ON THE "INTERNATIONAL RESIDENTIAL CODE"

NOTE: while the International Residential Code does permit terminating the vent in the attic space it is no advisable for two reasons:

1.Excess moisture will condense in the insulation which deteriorates insulation.

2. Sewer gasses are heavier than air, therefore excess sewer gas in the attic space will permeate into the living space below.

Uniform Plumbing code the auxillary vent MUST terminate through the roof.

[R.B.]

I was'nt going to terminate the vent in the attic, i was going to instal a tee in the attic and connect it to the existing vent threw the roof.

[LazyPup]

If you are under the International Residential Code you will be permitted to run a horizontal vent line and tie it into the stack but their are a couple points you should note.

At the point of tie in on the stack the "tee" should be installed upside down so the radiu curve is toward the top.

The horizontal line should be pitched at 1/4" per foot upward toward the stack.

If the length of the horizontal run is 40' or greater you must increase the line size by one nominal trade diameter.

[R.B.]

thanks for the heads up.

[MartinR]

Say LazyPup does that mean that horizontal vents lines tied into stacks are not allowed under the UPC.

Marty

[LazyPup]

That is correct. Under the Uniform Plumbing Code you may not have a flat horizontal vent. The minimum angle for an offset is 45deg.

[MartinR]

Thanks LazyPup for the reply.

Does the same rule for horizontal vents apply in this case that they must start at least 6" above the flood level of the highest appliance? Or may the vent turn 45 deg starting right after the sani tee? I was hoping to revent 3 fixtures to the main stack so to minimize the number of penetrations in a metal roof. I figured if I could terminate the main house vent at the ridge it could easily be flashed to prevent water intrusion. Even if I can offest right after the sani tee I doubt I have enough head room to carry all the way to the main vent. Also is it possible there are local codes that may supercede this requirement. I live in San Luis Obispo CA.

Thanks, Marty

[LazyPup]

If you live in Calif. you are under the Calif. Code which is based upon the Uniform Plumbing Code. In that case, you are not permitted any flat horizontal venting. The miximum angle for an offset is 45 deg. from vertocal and all vents must terminate through the roof.

I would begin by contacting your local zoning commission to determine which code is in your locality.