Glenn: 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.