The building codes that govern the trades are, by and large, enforced by whatever municipality the work is being done in. Most jurisdictions have a plan review process that usually, but not always, includes structural, mechanical, plumbing and electrical, site preparation and other germane tradecrafts. People whose jobs are to know what the locality will and won’t accept review the plans. The plan reviewers are pretty fussy about a lot of things. Often they will “red line” a set of drawings with required changes the architect or engineer signing the plans must make in order for the project to be given the green light.
   One thing the plan checker doesn’t do is look for continuity. Strictly speaking, it is not his or her job. But it is your job as a subcontractor. With the advent of computer aided drafting, word processing and other enhanced data transfer methods, it has become more and more common for architectural and engineering firms to “cut and paste” details, specifications and other boiler plate information onto the plans from one job to another. Any changes or differences can then be made without having to completely redraw or retype the particular pieces of information. This works great for the architects or engineers, as far as that goes, but this timesaving device can create a nightmare for the unwary contractor. Remember the law of unintended consequences.

The Gotcha!
Let’s take a hypothetical situation: You bid a job for ABC Construction in one city or town. The plans call for roof drains, overflow drains, lead flashing, lambs tongue downspouts and all relevant piping. The project goes well and the contractor is so pleased with your performance he negotiates the next building that, ostensibly, is identical to the previous one, just in a different locale. A review of the new plans shows the plumbing is an exact duplicate except the new municipality allows scuppers instead of roof drains. However, the original roof drain details are still on the plans for the new building and the specifications are still in the spec book. You bid the job without roof drains, since the roof plans now show scuppers, and all the elevation details show them as well.
   Let’s say you’ve worked for this contractor before and all has gone well. His project manager goes through the plans and lists everything that the plumbing contractor is responsible for. He picks up the roof drain details and spec sections and includes that in your scope of work. They send you a contract with the right numbers in the right places and you sign it after only a cursory examination. You have just agreed that the roof drains are a part of your scope of work, even though you may have excluded them from your proposal and bid and even though they are not required on this building.
   In most cases this issue is easily resolved with a phone call or job site meeting. Let’s say, though, the owner and the contractor get “fluffy” with each other. Let’s say the owner then looks at the plans, at your contract and at the general contract. He then demands a credit for the roof drains which were not put in but were clearly included in your work scope. You can see where this is going can’t you?

Caveat Subcontractor
The previous scenario was deliberately obvious for the purposes of this discussion. There are many, and varied, instances of subtle deviations from the norm or additions to the project in verbiage or notes in obscure places on the plans which you will be responsible for if you don’t note them early on and exclude them (or include the costs in your bid). The reason this type of issue can crop up is simple; architects and engineers can pre-empt the codes. If an engineer says that something he designed will work, even if it is questionable under the code, the building department will defer to his expertise in most cases since, as a registered professional, he stands behind the item in question. If you either fail to note, or worse, ignore these items, you do so at your peril.
   It is well for you to remember that most contract law in the United States is black and white. Gray areas are generally reserved for TV shows where some smart lawyer finds a loophole and wins the day on a technicality. It happens, to be sure, but the costs to you and your company will be staggering. Most times if it is in writing it is binding. Knowing the codes backwards and forwards doesn’t help you at all if you’ve agreed to something in writing, whether you intended to or not. 
   The best advice is to scour all the plans and note every single thing that might be included in your job description. Done early, this will ensure that your bid will be comprehensive and there won’t be any surprises down the road.