DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Plumbing Forum > Floor Drain Question for GlennJanie

Help Support House Repair Talk by donating using the link above.
Thread Tools Search this Thread
Old 07-15-2006, 04:29 AM  
Join Date: Mar 2006
Posts: 44
Default Floor Drain Question for GlennJanie


I have a question regarding venting of floor drains via 'combination waste and vents' under the IRC 2003.

I am ready to build a split level that has as it's on grade 1st level the following:

Basically I have a slab with an upper story.

The building drain will run under the slab and will drain the laundry group and bath group from the right.

The upper story has two full bath groups and a kitchen group that drains to the main stack at the upper area of the garage. This stack goes through the roof.

I'm interested in putting in a floor drain both in the garage and mechanical room floor. Mechanical room will have a gas boiler and water heater. Would like the floor drain to handle any releases from pressure valves, leaks, etc..

According to the IRC, both floor drains need to be trapped as well as vented.

My question is mostly about the 'venting' of these floor drains using a 'combination waste and vent'.

IRC 2003 is about as clear as mud regarding thes type drains.

I could actually vent the mechanical room floor drain with little problem by going vertically and tying into the vents for the laundry and bathgroup on the first floor that will vent out the side of the structure.

Venting the garage floor drain is a bit trickier because of the distances.

If I understand the combination waste and vent concept, I can simply drain the floor drain to the building drain without additional venting because the building drain and floor drain will actually serve as the vent.

While typically trapped fixtures are limited in their runs based on pipe sizes, floor drains under the IRC, at least under the Code Commentary, have no limits on run lengths.

But I find the entire concept confusing as described in the IRC.

Can you shed some light on this for me?

Will the floor drains as drawn work as a 'combination waste and vent' to your understanding or under IRC, UPC or Kentucky Code?

Will venting the garage floor drain with an upstream vent be a better alternative/possibility?

Thanking you in advance for your professional opinion.

manhattan42 is offline  
Reply With Quote
Old 07-15-2006, 01:36 PM  
Senior Member
Join Date: Mar 2006
Posts: 2,990
Liked 4 Times on 4 Posts


Hello Manhattan 42:
I was at a PHCC state convention a few years ago in which there was a Code Committie meeting conducted as a demonstration of the committie's work. One of the things brought up in that Committie meeting was a representative from the IRC who said they had all the fire insurance companies on board and that Kenucky would have to switch to their code to keep up. He called the KY Code a Hoover Code and really tried to talk it down.
Our code was based on the Code implemented in the Hoover Era but has not just been allowed to sit and stagnate, we pride our code as being the most stringent plumbing code in the States. That being said, I will not quote from the IRC but if you are familliar and comfortable with it then I have no problem with you using it.
According to the Kentucky Plumbing Code: 1. The mimimum size of a floor drain is 3" and each drain requires a trap and an individual vent. 2. The combination drain-vent is not allowed; that is called a "wet vent". 3. In a multi-story application there must be a seperate vent stack; nothing can be drained into a vent. The stack vent being that part of a stack starting at the highest horizontal drain and extending through the roof. 4. The vent always occours after the trap; "upstream" venting would not be allowed. Your floor drains, then, would be vented up through the nearest wall and tied in (or revented) to the stack above the highest horizontal drain. Your vents may be 1-1/2" diameter which relieves the problem of running them in a 2x4 stud wall. If a seperate vent stack is used it must tie into the bottom of the main stack (or building drain) so that its base is washed and run "full size" into the stack vent or through the roof.
Now, I know this doesn't square with the IRC or some other codes but that is the Kentucky code. I apreciate the opportunity to help and I wish you the very best with your project.
glennjanie is offline  
Reply With Quote
Old 07-17-2006, 11:46 AM  
Join Date: Mar 2006
Posts: 44

Thanks for your thoughts.
Can't seem to get a straight answer under the IRC because wet venting is allowed and for floor drains with intermittant use, combination vents can also be applied.

IRC allows for no distance limits on the runs because of limited flows and increased pipe sizes (2" IRC).

I suppose the best thing to do is to revent the floor drains or vent them to fresh air as I can.
manhattan42 is offline  
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Similar Threads
Thread Thread Starter DIY Home Repair Forum Replies Last Post
Washer Drain Question? prh44 Plumbing Forum 5 01-22-2012 07:51 PM
Basement floor drain question headmedic Plumbing Forum 3 06-04-2011 05:34 PM
AC drain pipe question sailtexas HVAC 2 08-03-2010 02:45 PM
Condensate drain question Phatboy HVAC 5 10-09-2007 07:20 PM
Floor Drain question Mudball Plumbing Forum 9 06-24-2006 10:04 PM

Newest Threads