There is no one place a freestanding tub drain goes. Pennsylvania’s residential code text sets the tub’s waste outlet at not less than one and a half inches. The outlet gets a watertight stopper. An overflow, where one is installed, gets the same minimum. What the code text doesn’t say is where the drain falls.
The tub’s own installation sheet decides that, so the tub and its drain are worth settling with the floor plan before the floor is closed.
That shapes the plan. Where the drain falls, whether the tub has an overflow and where the trap connection can be reached all follow from the tub you pick. Each one’s easier to settle on paper. Close the floor first, and a change to any of them can mean opening it again.
What Does the Code Say About a Freestanding Tub Drain?
It sets sizes and a few rules about access. It doesn’t set a position. The code text puts a bathtub’s waste outlet at not less than one and a half inches in diameter, with a watertight stopper on it. Where an overflow is installed, it gets the same minimum.
Those lines sit in the plumbing fixtures chapter of Pennsylvania’s 2021 residential code, as published on UpCodes. A bathtub’s waste outlet can’t be less than one and a half inches in diameter. The outlet “shall be equipped with a watertight stopper.” An overflow, where one is installed, can’t be less than one and a half inches either.
And the same chapter sets fixture tail pieces for bathtubs at not less than one and a half inches.
Trap sizes live in the code’s chapter on traps. Its table of minimum trap sizes lists a bathtub, with or without a shower head or whirlpool attachments, at one and a half inches. Where a fixture’s tailpiece is larger than the table size, the trap takes the tailpiece’s nominal size. And a trap can’t be larger than the drainage pipe it discharges into.
Every one of those figures is a minimum. The plumber confirms the details on the job against the code edition the local building office enforces. Your part’s earlier and simpler. Pick the tub, then let its sheet and those minimums meet on the plan. The sheet shows what the tub needs. The minimums come from the code text.
Where Does a Freestanding Tub Drain Go?
The code text sets sizes and calls for a watertight stopper. What it doesn’t say is where the waste outlet sits in the tub, or where the drain lands in the room. The tub’s own installation sheet is the place to look for that. So the tub comes first. Then the plan.
Lang’s own post on choosing a freestanding tub for your bath remodel comes at it from the tub’s side. It notes that some tubs carry special installation requirements that depend on size, shape and weight. It also tells readers to check that the room suits the tub they’ve chosen. Both are reasons to settle the model before the drawing.
So ask for the sheet for the tub you’re weighing. Then ask the designer to confirm from it where the drain falls and what sits beneath that spot. Those answers shape the plan. Drawing the plan first, around a tub nobody has picked, leaves them open.
Does a Freestanding Tub Have an Overflow?
That depends on the tub, not on a rule that covers every tub. The code text sizes an overflow at not less than one and a half inches where one is installed. Note the wording: where one is installed. Whether the tub you’re weighing has one is shown on its own installation sheet.
So ask the designer and the plumber to confirm from the sheet which arrangement your tub has. Ask what the local building office expects, too. And the sheet carries both the outlet and the overflow, so read them together.
Why Plan Access to the Trap Connection?
Because the code text ties one kind of connection to an access opening. Slip-joint connections are allowed only for tubular waste piping. And only between a fixture’s trap outlet and the connection to the drainage piping. Where one is used, it has to be accessible through an opening not less than 12 inches in its smallest dimension.
Where that connection sits, and how someone gets to it, are plan questions. So ask the designer to show on the plan where the opening will go, and ask before the floor is closed. On a drawing, that’s a line. After the floor is closed, reaching that spot is a different job. An opening needs somewhere to live, and that somewhere is a decision. Make it on paper.
What Should You Bring to a Design Consultation?
The name of the tub you’re weighing and its installation sheet. Photos of the bathroom help as well. The sheet is where a designer can read the drain position from, instead of working around a guess. The photos cover what the sheet can’t: the room as it stands. Bring both if you have them.
Lang’s post on how shower drain size follows the fixture list explains that the code text sizes a shower trap by the total flow rate through its showerheads and body sprays. A tub asks something different. The trap table gives a bathtub its own minimum, and the sheet shows where the outlet falls. Same room, different question.
With the sheet in hand, bathroom remodeling with Lang’s designers can start with the tub on the plan. Bath designs vary with which bathroom you’re remodeling, who will use it and the space you have. The bathroom remodeling team can help design the space you want.
Bring the questions, too. Where does the drain fall on this tub? Does it have an overflow? How do the outlet and the trap line up with the code text’s minimums? Where will the access opening go? Those are the ones the designer and the plumber can answer from the sheet, and they’re easier to answer while the plan is on paper.
Frequently Asked Questions About Freestanding Tub Drains
Is there one place a freestanding tub drain goes?
No. The code text sets the outlet size, calls for a watertight stopper, sizes an overflow where one is installed and requires access to a slip-joint connection. It stops short of saying where the drain falls. That comes from the tub’s own installation sheet, so ask the designer to confirm the position from the sheet for the tub you’re weighing.
What size is a freestanding tub drain?
The code text sets a waste outlet of not less than one and a half inches in diameter and tail pieces for bathtubs at the same minimum. The trap table gives a bathtub a minimum of one and a half inches. Where a fixture’s tailpiece runs larger than the table size, the trap takes the tailpiece’s nominal size. All of those are minimums, and the plumber confirms the details on the job.
Does the trap connection have to be reachable?
Where a slip-joint connection is used, the code text says it has to be accessible, through an opening not less than 12 inches in its smallest dimension. Whether a given tub’s connection is one of those is a question for the plumber and the designer. Ask where that opening goes while the plan’s still on paper.
Can the drain change after the floor is closed?
It may be possible, but the drain and the trap sit below the finished floor. Reaching them again can mean opening that floor back up. That’s why the tub and its drain are easier to settle while the drawings are still open. A change on a drawing stays on the drawing.
Who can help me plan the tub and its drain?
Lang’s design team. Design consultations are available in the showroom and online by appointment. Lang’s follows a 12-step process for a renovation. It includes a jobsite visit for a complete in-home analysis, and a stage where the design team finalizes all dimensions, floor plans and mechanical specifications. Bring the tub’s name and its installation sheet.
Bring Your Tub’s Installation Sheet to a Design Consultation
In Lang’s 12-step remodeling process, designers visit the jobsite for a complete in-home analysis before the design team finalizes all dimensions, floor plans and mechanical specifications.
Order helps. A tub and its drain are easiest to settle while the floor plan is still a drawing and the floor’s still open.
Lang’s 12-step remodeling process includes that jobsite visit and that final plan stage, and the design showroom is in Newtown.Design consultations are available in the showroom and online by appointment. Pick the tub first. Then bring its installation sheet and talk with Lang’s design team about where the freestanding tub drain lands, before the floor is closed.
