Working with Plumbing Subcontractors: Running the Job

by Tim Carter

Scheduling Tips Managing Change Orders Plumbing Standards

Scheduling Tips

Plumbers need to show up just as soon as a framed house is under roof. At the very least they must meet with or work in conjunction with the heating and air-conditioning contractor. If the job has sheet metal duct work, the heating and air-conditioning contractor gets first priority for system placement. Large ducts are far less flexible than 3- or 4-inch waste lines. Heating and cooling contractors, and plumbers, must agree who gets to run what where. Once both the plumbing and heating rough-ins are complete, you can call in your electrician.

Some plumbing can and should be installed as early in the job as possible.

Allowing an electrician on the job too soon can cause nightmares. Fifteen years ago the owner of a custom home I had built called me concerning a central vacuum cleaner that had a mind of its own. It would turn itself on and off randomly. The problem was traced to melted insulation on a low-voltage wire, which occurred when the plumber was sweating copper tubing joints. I would've loved to blame the plumber, but it was ultimately my fault for permitting the electrician to start work too early.

Some plumbing can and should be installed as early in the job as possible. Water and sewer lines installed soon after construction begins can become an asset to other trades that will subsequently work on the job. Septic systems need to be installed late in the job so that the leach field beds are not compacted or disturbed by other site work. Don't even think about landscaping, sidewalks, patios or outdoor lighting until your plumber tells you that he's done with his digging.

Avoiding Scheduling Conflicts

You can avoid scheduling problems among subcontractors by finding out how much time each sub needs to complete his job. If you want to try to compress time, you can ask if it is possible for other mechanical trades to be on the job site at the same time. More often than not this causes problems; always allow your subcontractors to make this call. If you get too many workers in one place at the same time, there are going be stolen tools, errors, damage and possible injuries.

If each subcontractor gives you a realistic estimate of the number of days required to complete his task, you can enter this data into very handy computer software programs that will create a critical path method or PERT chart that shows who is supposed to be where when. You can fax these to the necessary subs as the job progresses to update each one as to when they are supposed to show up on a particular site.

Managing Change Orders

Change orders slow jobs down and can create havoc. A change order can usually be traced to poor planning. Do whatever it takes to make sure your client has all the information at the beginning of a job so that change orders do not become necessary.

If something has to be changed, the order needs to be in writing. The best change orders spell out exactly what gets modified, what additional charges or credit will result, and what effect, if any, changes will have on the project completion date. Be sure to communicate with your plumbing sub about all changes that may affect his work.

Plumbing Standards

For the most part, minimum standards or workmanship for plumbing installations are spelled out by agencies such as ASTM, building code authorities and local code officials. Go to the Technical References section of this Web site for referrals to publications that detail approved practices.

Keep in mind, though, that codes are minimum standards, not necessarily the highest. If you want information on the best industry practices, look toward organizations like the Copper Development Association for answers to practical and technical questions.

About the Author

Tim Carter Tim Carter is an award-winning builder, remodeler and a licensed master plumber. He built custom homes for more than 20 years and is a syndicated newspaper columnist. His popular column, "Ask the Builder," appears weekly in newspapers nationwide. Tim also maintains a Web site,, which is updated on a daily basis.

The advice presented in this article reflects the personal views and professional opinions of the author and not necessarily those of the Copper Development Association. CDA believes that Tim Carter's independent viewpoint will be helpful.