Thread: Island venting method when other possible

I found this interesting as an official interpretation from the ICC concerning residential structures.

P3112.2 Vent connection. The island fixture vent shall connect to the fixture drain as required for an individual or common vent. The vent shall rise vertically to above the drainage outlet of the fixture being vented before offsetting horizontally or vertically downward. The vent or branch vent for multiple island fixture vents shall extend to a minimum of 6 inches (152 mm) above the highest island fixture being vented before connecting to the outside vent terminal.
REFERENCED SECTION:
P3101.2.1 Venting required. Every trap and trapped fixture shall be vented in accordance with one of the venting methods specified in this chapter.
! ! ! ! ! ! ! ! ! !
Q: Is the island fixture venting method, as provided in Section P3112.2 of the International Residential Code, permitted to be used in areas where it is possible to route the vent up and to an approved conventional terminus?
A: Yes. Island fixture venting, as prescribed in Section P3112.2, is an acceptable method for venting sinks and lavatories, and is not limited by the physical conditions of the surrounding construction. Although other acceptable methods for venting sinks and lavatories may be viable options, any of the venting methods provided in Chapter 31 are acceptable as indicated in Section P3101.2.1.

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Loop vent, a.k.a. a "Chicago loop". Been around for decades, not just for islands, oft used for kitchen sinks under window banks too.

Here in Illinios you can only use an island vent for when you can not use a standard venting. Illinois does even specify what fittings are needed to make the loop of the vent. Here is a photo of one for those that have no idea what we are talking about.

Here's the description and the illustration from the Illinois Plumbing Code:

890-120 Definitions
"Island Fixture Vent". A vent in which the vent pipe rises as near as possible to or above the highest water level in the fixture vented and then turns down before connecting to the stack or main vent."

890-1600 Special Venting for Island Fixtures.
--a) Traps for island sinks and similar equipment shall be roughed-in above the floor and shall be vented by extending the vent as high as possible, but at least the drainboard height and then returning it downward and connecting it to the horizontal sink drain immediately down stream from the vertical fixture rain. Back to back islan vented fixtures shall meet the requirements of Section 890.1460.
--b) The returned vent shall be connected to the horizontal drain through a Y-branch fitting and shall be provided with a vent taken off the vertical fixture vent by means of a Y-branch immediately below the floor and extending to the nearest partition and then through the roof to the outside atmosphere or may be connected to other vents at a point at least six (6) inches above the flood level rim of the fixture served. Drainage fittings shall be used on all parts of the vent below the floor level and a minimum grade of one-quarter (1/4) inch per foot back to the drain shall be maintained. The returned bend used under the drainboard shall be a one-piece fitting or assembly of a 45 degree, a 90 degree, and a 45 degree elbow in the order named in section 890.1340, and Appendix K Illustration GG.

No only.

Originally Posted by H.G. Watson, Sr.

Here's the description and the illustration from the Illinois Plumbing Code:

890-120 Definitions
"Island Fixture Vent". A vent in which the vent pipe rises as near as possible to or above the highest water level in the fixture vented and then turns down before connecting to the stack or main vent."

890-1600 Special Venting for Island Fixtures.
--a) Traps for island sinks and similar equipment shall be roughed-in above the floor and shall be vented by extending the vent as high as possible, but at least the drainboard height and then returning it downward and connecting it to the horizontal sink drain immediately down stream from the vertical fixture rain. Back to back islan vented fixtures shall meet the requirements of Section 890.1460.
--b) The returned vent shall be connected to the horizontal drain through a Y-branch fitting and shall be provided with a vent taken off the vertical fixture vent by means of a Y-branch immediately below the floor and extending to the nearest partition and then through the roof to the outside atmosphere or may be connected to other vents at a point at least six (6) inches above the flood level rim of the fixture served. Drainage fittings shall be used on all parts of the vent below the floor level and a minimum grade of one-quarter (1/4) inch per foot back to the drain shall be maintained. The returned bend used under the drainboard shall be a one-piece fitting or assembly of a 45 degree, a 90 degree, and a 45 degree elbow in the order named in section 890.1340, and Appendix K Illustration GG.

No only.

Yep Thanks for the post just as I said its a consideration for Special Venting for Island Fixtures. Which is how the local plumbing inspector and plumbers interpret the Illinois code. So if a fixture is not an island fixture it must be vented by traditional means.

Originally Posted by Ron Hasil

Yep Thanks for the post just as I said its a consideration for Special Venting for Island Fixtures. Which is how the local plumbing inspector and plumbers interpret the Illinois code. So if a fixture is not an island fixture it must be vented by traditional means.

We just use an AAV and go on with life! I'm betting that an AAV can not be used IL or in Chicago.

Originally Posted by Scott Patterson

We just use an AAV and go on with life! I'm betting that an AAV can not be used IL or in Chicago.

You hit the nail on the head there. Illinois does not allow any mechanical device to be used for venting. Their code also states that venting must allow for the admission and or emission of air.

Section 890.1420 Stack Vents, Vent Stacks, Main Vents

a) Design. A properly designed and installed venting system, in conjunction with the soil or waste system, is essential to protect trap seals and prevent siphonage, aspiration, or back pressure. The venting system shall be designed and installed to permit the admission or emission of air so that under normal and intended use the seal of any fixture trap shall never be subjected to a pneumatic pressure differential of more than a one (1) inch water column. If a trap seal is subject to loss by evaporation, means shall be provided to prevent loss of the trap seal. (See Section 890.410(f).)

b) Installation. A stack vent, vent stack or a main vent shall be installed with a soil or waste stack whenever back vents, relief vents, or other branch vents are required. (See Appendix K: Illustration A.)

c) Terminal. Vents shall terminate independently above the roof to the outside atmosphere, or shall be connected to another vent at least six (6) inches above the flood-level rim of the highest fixture. (See Appendix K: Illustration B.)

d) Main Stack. Each building in which plumbing is installed shall have at least one main vent stack no smaller than three (3) inches for each building drain installed. (See Appendix A: Table K, and Appendix K: Illustration C.)

e) Building Sub-drain Sump Vent Sizes. Building sub-drain sump vents shall be sized in accordance with Appendix A: Table K.

Section 890.1480 Types of Fixture Trap Vents

a) Trap Vent. No trap vent shall be installed within two pipe diameters of the trap weir. (See Appendix K: Illustration N.)

b) Common Vent. A common vent, installed vertically, may be used for two fixture traps when both traps connect with a vertical waste at the same level. (See Appendix K: Illustration O.)

c) Vertical Wet Vent. A vertical wet vent may be used for two fixtures set on the same floor level, but connecting at different levels in the stack, provided the vertical drain is one (1) pipe diameter larger than the upper fixture drain and that both drains conform to Appendix A: Table I. (See Appendix K: Illustrations P and Q.)

d) Mechanical Vents. Mechanical devices shall not be installed in lieu of vent piping.

Originally Posted by Ron Hasil

You hit the nail on the head there. Illinois does not allow any mechanical device to be used for venting. Their code also states that venting must allow for the admission and or emission of air.

Section 890.1420 Stack Vents, Vent Stacks, Main Vents

a) Design. A properly designed and installed venting system, in conjunction with the soil or waste system, is essential to protect trap seals and prevent siphonage, aspiration, or back pressure. The venting system shall be designed and installed to permit the admission or emission of air so that under normal and intended use the seal of any fixture trap shall never be subjected to a pneumatic pressure differential of more than a one (1) inch water column. If a trap seal is subject to loss by evaporation, means shall be provided to prevent loss of the trap seal. (See Section 890.410(f).)

b) Installation. A stack vent, vent stack or a main vent shall be installed with a soil or waste stack whenever back vents, relief vents, or other branch vents are required. (See Appendix K: Illustration A.)

c) Terminal. Vents shall terminate independently above the roof to the outside atmosphere, or shall be connected to another vent at least six (6) inches above the flood-level rim of the highest fixture. (See Appendix K: Illustration B.)

d) Main Stack. Each building in which plumbing is installed shall have at least one main vent stack no smaller than three (3) inches for each building drain installed. (See Appendix A: Table K, and Appendix K: Illustration C.)

e) Building Sub-drain Sump Vent Sizes. Building sub-drain sump vents shall be sized in accordance with Appendix A: Table K.

Section 890.1480 Types of Fixture Trap Vents

a) Trap Vent. No trap vent shall be installed within two pipe diameters of the trap weir. (See Appendix K: Illustration N.)

b) Common Vent. A common vent, installed vertically, may be used for two fixture traps when both traps connect with a vertical waste at the same level. (See Appendix K: Illustration O.)

c) Vertical Wet Vent. A vertical wet vent may be used for two fixtures set on the same floor level, but connecting at different levels in the stack, provided the vertical drain is one (1) pipe diameter larger than the upper fixture drain and that both drains conform to Appendix A: Table I. (See Appendix K: Illustrations P and Q.)

d) Mechanical Vents. Mechanical devices shall not be installed in lieu of vent piping.

Hey, what do you expect from the state/city that does not allow NM (Romex) cable to be used. It works fine everywhere else in the country, just not in IL!

Originally Posted by Scott Patterson

Hey, what do you expect from the state/city that does not allow NM (Romex) cable to be used. It works fine everywhere else in the country, just not in IL!

Scott,

The air is different there.

So is the electricity.

A lot of differences in the IL codes are due to unions.

Originally Posted by Jeff Remas

A lot of differences in the IL codes are due to unions.

Being a good ole Southern Boy, I was not going to bring that up. Hmmmm, now if we could just get GM to realize that they are the problem as well.

Originally Posted by Jeff Remas

A lot of differences in the IL codes are due to unions.

Originally Posted by Scott Patterson

Being a good ole Southern Boy, I was not going to bring that up. Hmmmm, now if we could just get GM to realize that they are the problem as well.

Scott,

I was avoiding that for the same reason.

Originally Posted by Jeff Remas

A lot of differences in the IL codes are due to unions.

Is that a bad thing?

Originally Posted by Ron Hasil

Is that a bad thing?

Depends on which side of the ball you are one and where the ball is placed on the field of play.

We allow the loop vents for islands. However we require the drain side to be 2" and the venting side to be 1 1/2". That way you can't connect them backwards which could cause siphonage of the p-trap.

Originally Posted by Ron Hasil

Is that a bad thing?

As Jerry said it all depends.

IMHO, when codes are designed to protect a profession or to help a profession to charge higher fees, then yes it is a bad thing. No reason in the world an AAV can not be used or Romex (NM cable) can not be used when it is used in just about every other state in the union without any problems.

Oh well, it is an age old problem that we are not going to solve. All we can do is to sit wonder why..

Originally Posted by Scott Patterson

As Jerry said it all depends.

IMHO, when codes are designed to protect a profession or to help a profession to charge higher fees, then yes it is a bad thing. No reason in the world an AAV can not be used or Romex (NM cable) can not be used when it is used in just about every other state in the union without any problems.

Oh well, it is an age old problem that we are not going to solve. All we can do is to sit wonder why..

There are at least 10 states that do not allow AAV's, and Illinois code will not allow them due to the fact an AAV can not do anything for positive pressures in the venting system, which is why they want vent pipes to the roof to allow for the emission of air.

I have seen AAV's used by home owners that call me and tell me their home has a sewer gas smell. Every time it was the AAV since it did not allow for air emissions the trap lost its seal when they ran the sink on the second floor.

Originally Posted by Wayne Carlisle

We allow the loop vents for islands. However we require the drain side to be 2" and the venting side to be 1 1/2". That way you can't connect them backwards which could cause siphonage of the p-trap.

If you check the illustration GG I posted you will find a similar specification for different trade size in Illinois for the island special vent. The Appendices and illustrations therein are a part of the Illinois Plumbing Code (as are the words, descriptions, etc. contained within the illustrations).

Local home rule authorities in Illinois have approved use of the special vent for islands for plumbing where the sink cabinet was on outside wall under windows far from an inside wall suitable for containing venting. Plumbed "as an island" to avoid freezing issues, key has been through the floor and the area below being maintained above freezing on those occasions.

In Illinois, incorporated home-rule areas the local AHJ office IS the authority interpreting what is and is not an island. Unincorporated areas or areas without home-rule the county is the AHJ. The City of Chicago is often excepted on rules/laws or has special provisions (and/or the County of Cook) for many of the laws in Illinois, often not specifically named, but identified by area (city, county, home rule authority) with a greater than specified minimum population.

P.S. Note to 2nd paragraph above: IME this has been limited to instances involving structural masonry construction walls.

Originally Posted by Ron Hasil

There are at least 10 states that do not allow AAV's, and Illinois code will not allow them due to the fact an AAV can not do anything for positive pressures in the venting system, which is why they want vent pipes to the roof to allow for the emission of air.

I have seen AAV's used by home owners that call me and tell me their home has a sewer gas smell. Every time it was the AAV since it did not allow for air emissions the trap lost its seal when they ran the sink on the second floor.

That is also why you must have at least one vent stack to the exterior with all homes that have AAV's, to release any positive pressure. As for those ten states, I would also bet that most of the trades in those states are union controlled.

the plumbing code requires a cleanout in the vertical portion of the foot vent which is placed in the nearest partition. so if you find a cleanout in a wall near the island sink it just might be done correct.

I do work in big cities like Chicago, as well as unincorporated areas like Flowerfield IL. If a sink is on an outside wall in front of a window, they run the drain horizontal to one of the sides of the window then into a tee fitting draining down into the sanitary waste system, and up through the roof for the vent. 99% of the homes have two vents to the roof, one is the main vent stack and the other is the sink vent stack. In newer construction they have been running the sink vent to the main stack vent in the attic.

I just finished my continued education class, which is required for all plumbers to do to renew their license, in Southern Illinois. It was ran by the Plumbing department from Springfield IL, and they talked about using Special Venting for Island Fixtures, and told all the plumbers in attendance there that it is to be used only when the fixture is installed in an Island configuration, as pictured in the Illinois plumbing code book.

Originally Posted by Ron Hasil

Here in Illinios you can only use an island vent for when you can not use a standard venting. Illinois does even specify what fittings are needed to make the loop of the vent. Here is a photo of one for those that have no idea what we are talking about.

I see this design used in much of the new homes I inspect. The home I am inspecting tomorrow has the same design as a few others in this development and I can about guarantee this is what I will find.

The old "Ohio Plumbing Code" required that in order to use and 'island loop vent', the fixture had to be an 'island' that could be completely walked around. The "International Plumbing Code" doesn't have this requirement, however there are other venting methods, (combination drain and vent, air admittance valves), that have made 'island loop vents' virtually obsolete here in Ohio.

Originally Posted by Scott Patterson

That is also why you must have at least one vent stack to the exterior with all homes that have AAV's, to release any positive pressure. As for those ten states, I would also bet that most of the trades in those states are union controlled.

Which is also why those ten states are probably loosing jobs!

My aunt, bless her soul, left the South 40 years ago and married a fellow from Illinois who became a plant manager for Caterpiller. I'll never forget the conversation we had regarding the purpose, validity, etc. of unions. She thought it was stupidity that kept unions out of the South. The truth is, southerners had it right all along. Jobs are now going South. While GM and Chrysler are failing, Volkswagen, BMW, Nissan and Kia are expanding. Where do the Germans, Japanese, Koreans go to build new automotive factories? It isn't the rust belt. While the North is loosing jobs, the South is gaining jobs. Why, because unions tend to drive the cost of doing business too high. In a competitive world, unions are a dinosaur. I could go on, but, this is not the place.