But wait, there’s more! We also need to bring larger lines to the second floor! – Dawn J., Scranton, Pa.
A: I see these difficult situations in both new and old homes. As a master plumber, I draw a lot of isometric plumbing and riser diagram plans for homeowners so they can get a plumbing permit. When I study their floor plans, I am stunned to see how many architects don’t think about how pipes need to get from one level to the next with as few bends as possible.
This is one reason why I think architecture students should need construction, not drawing jobs for half the time they graduate. You have to work side by side with carpenters, plumbers, and HVAC contractors on actual construction sites. If these young, fertile minds actually have to figure out how to make things work in the real world instead of on a computer monitor, their plans will be much better in the future.
Ancient architects often solved these problems with strategically placed walls, pantries and cabinets on the level below the bathroom. A wall on the lower level could be 6 inches thick for plumbing, although 8 inches is far better.
An architect can make one or more walls of a cabinet thick enough to accommodate the pipe or ducts. Adding a second wall can create a false cavity in the back of a closet. This cavity is good for getting a large sewer line from one level to the next.
Corner pipe chases are also a great way to disguise pipes or ducts that need to go from one level to the next. To balance the look in one room, you can always add a faux in another corner. In the past, I’ve even built a long shelf that extends down about 16 inches from the ceiling, spanning the space between the needed and false pipe trackers. All kinds of decorative items can be placed on the shelves and this will take your eyes off the chases. The average person believes the chases are required to prop up the huge horizontal shelf.
It is important that the drain line is flexible. A typical residential bathroom with toilet, shower, bathtub and even two sinks can be connected to a 3-inch pipe.
This pipe can run a considerable distance horizontally, even up to 25 feet or more, before it has to be twisted down to get to the next level. You can even have multiple 45 degree fittings in this horizontal run. Note, however, that for every foot of horizontal run this pipe must have a 3/16 inch slope so that the fluids in the pipe do not overflow the solids.
Knowing this, you may be able to extend the drain pipe to another room on the lower level outside of the main bathroom upstairs. The chase could end in a corner of another room or even be in a closet. It all comes down to how lucky you are with the run of the floor joists under the new master bathroom.
Note that when creating holes in floor joists for pipes, there are very strict building code and structural best practices requirements. Notching floor joists is never to be done as it weakens them. Holes drilled through floor joists must be of specific sizes and in specific locations. The building code deals with these and there are some helpful guides online for you to refer to.
If you are using PVC or ABS plastic tubing for the bathroom, once all of the leak tests have been performed, you will need to soundproof the sound tubes in both the ceiling and the vertical tube tracker. The water flowing through the plastic pipes vibrates them with ease. Because of this, it sounds like there is a waterfall in your walls when there is no insulation. You can get rid of this noise with non-hub cast iron drain pipes.
Your piping challenges are the same as for the drain pipe, only bigger. Plumbing is much larger than a plumbing stack and takes up a lot more space. You may need to construct and clad soffits in a room to create a tray ceiling in a room or two so the soffit doesn’t stick out like a sore thumb.
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