Hollysprings, you made the following statement "You can't have bathrooms in two different structures share the home's main sewer drain." Can you show any zoning/building laws that agree with your statement? I believe you statement is not true. I just built a detached guest house and the bathroom was tied into the main home's existing sewer drain. All the guest houses and pool houses in this area are hooked up in similar ways to sewers or septic systems. If the structure is part of the main property and not a second home/apt that might be rented out then it is all hooked up together. They actually don't want separate hook ups with different meters because that would make it easy for some homeowners to rent that space out, which the town does not want at all.

I agree that this discussion has no doubt gotten far more complex than what they originally intended but you cannot blame me. If all they originally wanted was a hose bid near the garage I would have began by suggesting a lawn hydrant, however the original post was a bit more complex than that: Quote from the original post:- "I will be installing a slop sink, house bib and possibly a small water heater to start. Might also add a half bath in the future" I am merely pointing out that if they intend to install a sink or perhaps a half bath in future the code requires an approved drainage system as a pre-requisite to install any fixtures inside the structure. Taking this to the next level, we have no yet even begun to discuss the problems of installing fixtures I an unheated structure in a cold climate. If you were asking my personal opinion I would say the whole idea will soon prove to be cost prohibitive. NOW FOR THE NEXT QUESTION: "What is the rationale for requiring a separate sewer tie-in for outbuildings? ANSWER: All of the DWV (Drain, Waste & Vent) lines inside a structure eventually combine into one line before passing through the footer wall to exit the structure. That single line is properly defined as the house or building "Main Drain". Code requires that we must install a "Main cleanout" on that line within 3 of the footer wall. For structures built over a basement the main cleanout is generally installed immediately inside the footer wall in the basement. For structures on slab it is generally located outside the structure within 3 of the footer wall. For structures on a raised foundation with a crawlspace the cleanout may be inside or outside the structure. The main cleanout officially designates the end of the "Main Drain" and the beginning of the "house or building Sewer". On a residential property the "House Sewer" is generally consider the primary sewer line for the property and it would discharge directly into a "Municipal Sewer" or a "Septic Tank. Code only allows one line to connect to the municipal sewer or the septic tank, therefore when we have additional outbuildings that are equipped with plumbing fixtures the "building sewer" from the outbuildings must tie into the "House Sewer" before tying into the municipal sewer or septic tank. It must also be mentioned here that all DWV and Sewer Lines are sized by the DFU (Drainage Fixture Unit) load calculation method. The code gives us a list of all the fixtures that may be connected to a drainage system in both residential and commercial plumbing systems. The list then gives us a minimum size of drain opening or pipe and the DFU load value for each fixture. (IRC table 3004.1 & table 3201.7) Example: Lavatory 1-1/4" pipe & 1DFU, shower/tub 1-1/2 pipe and 2DFU, Shower stall 2" pipe and 2DFU, watercloset with 1.6gpf or less flush min. 3" pipe and 3DFU. A watercloset with greater than 1.6gpf = 3" line and 4DFU, kitchen sink 1-1/2" pipe and 2DFU, A Baptismal pool in your church is a 2"line and 3DFU while an office water cooler is 1-1/4" line and 1DFU and an Autopsy table at your local coroners office is a 2" line and 3DFUs. The code then gives us another table that lists the maximum number of DFUs that may be conveyed by each size of pipe. (IRC table 3005.4.1) Example: For the DWV lines within a structure the table lists the following 1-1/4" =1DFU 1-1/2"=3DFU 2"=6DFU 3"=20DFU 4"=160DFU When designing a DWV system we must begin at each fixture and attach the code required size of drain line then at every junction where two or more pipes combine we must compute the total DFU load at that point and select the appropriate size of pipe from that point onward. When we have more than one structure equipped with plumbing on a building lot we must do basically the same thing. We begin by calculating the total DFU load for each structure. At every point where two or more building sewers combine we must add the DFU load for each structure to determine the total combined load on the sewer line at the junction then we consult another table that defines the maximum number of DFUs permitted on each size of pipe. Example from IRC table3005.4.2 3" with ¼"/ft pitch 42DFU 4" with ¼"/ft pitch 216DFU 3" with 1/8"/ft pitch 36DFU 4" with 1/8"/ft pitch 180DFU (The IRC permits a 3" line to run with a 1/8"/ft pitch only with the expressed written consent of the local authority having jurisdiction)

Sorry, some non-garage crises took me away for a bit. Thx for the replies! We've kind of figured it out, but to satisfy any lingering curiosity... Yes, the town basically wants a 6" "plateau"(for lack of a better term) of a foundation. We will just have to create an incline in the driveway to drive up into it. Sounds weird to me, and I think it will also look weird, but at this point it is path of least resistance in getting this over with before snow flies. They tell me this is some new regulation. The driveway will just have to be graded accordingly. If we wanted the garage "at grade" (this might not be the correct terminology as I am a layperson, but "totally flat on the ground, not raised" is what I mean), it could be done, but it would set off a chain reaction of MULTIPLE other town-required changes resulting in the builder having to go with truss roofing. In other words, one change wouldn't directly cause the other, but the end result would be the same for us: at-grade with truss roof. I will look into attic trusses, Ichabod Crane, if we end up having t go that route! Thanks! And our original plan was to build on-site with a local contractor, but it just did not work out. We contacted several companies/individual contractors over the course of a year and had a lot of no-shows or no return calls. I guess construction business in my area is going well and nobody needed my particular job. So we decided to roll the dice and go pre-fab. So far they've been very easy to work with and very patient with the many questions and changes from our local municipality. Thanks again, all!

I like the idea of adding an Arbor over the 2 car garage, and then it looks like a 3rd off to the right. This would be one of the least expensive options, but adds so much style, fills the space and add a little craftsmanship to the home.