Pipe Placement 101
Ensure your plumbing connections are in the right spots with this guide to kitchen and bath rough-in.
Synopsis: Plumber Brad Casebier provides this guide to kitchen and bath rough-in, which works with about 80% of the entry-level to mid-level fixtures he and his crew install. For the bathroom, diagrams show rough-in locations for a tub/shower, a vanity sink, a pedestal sink, and a toilet. For the kitchen, rough-in locations are shown for a sink, and a second drawing shows how to place an ice maker. For each room, Casebier provides a list of “gotchas,” or situations you can avoid with a proper rough-in. He also includes guidance and “gotchas” for roughing-in a laundry room. A chart shows specific Uniform Plumbing Code and International Residential Code requirements for securing seven different types of pipe and tubing in both horizontal and vertical spaces. A second chart shows the UPC and IRC requirements for minimum trap size for 14 different fixtures.
As a plumbing contractor, I am responsible for making sure that the water-supply lines and drainpipes are where they are supposed to be when my crew and I show up to set the fixtures. The best way to ensure a correct rough-in is to follow the instructions for each individual fixture specified in the “cut sheets,” or product diagrams. These measured drawings, which show locations for supply and waste lines, are available at manufacturers’ websites and from suppliers that sell the product line.
If you’re working on a relatively basic kitchen or bath, you can use the typical dimensions shown here, which work with 80% or more of the entry-level to mid-level fixtures we install. There are exceptions to these rules, however, especially with high-end products. I always encourage clients to make selections early; I also remind them that any changes later will result in extra charges and that the extras don’t stop with me. A big redo can involve several trades — including carpenters, drywallers, and tile setters — and can cost hundreds, even thousands, of dollars. It also can mean a delay in the project, which can affect financing and occupancy.
Here are some of the kitchen, bath, and laundry-room plumbing problems we see regularly. Described as gotchas, these items often fall through the cracks and lead to problems down the road.
Common bathroom gotchas
Even though a bathroom is usually the smallest room in a house, a lot can go wrong when you’re building it. Use this list to avoid some of the most common bathroom-plumbing missteps.
While code requires only a 30-in. space for a toilet, 15 in. from a cabinet or adjacent wall can make you feel claustrophobic. Try for at least a 34-in. opening, and make sure there’s space for the paper holder. Roughing in 13 in. instead of 12 in. from the back wall leaves room for the trim and the drywall.
A rockin’ throne
Wobbly toilets ruin wax seals in short order. Add extra blocking around the waste riser, and make sure the toilet is shimmed and caulked at trim-out.
No room for the escutcheon
It’s best to know the type of base trim that will be installed. A tall baseboard can interfere with the trim ring around the toilet stub-out. The same thing can happen when supply lines are too close to cabinet backs and side.
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