Wall-Mounted or Floor-Mounted Tub Filler — and How High Should a Wall-Mounted Tub Spout Be?

Should a freestanding tub have a wall-mounted or a floor-mounted filler?

Wall-mounted if the tub sits close to a wall you can put a valve in; floor-mounted if it stands away from the walls. A wall filler only works when its spout can reach over the rim — Waterworks’ wall-filler instructions tell the installer to check the tub’s measurements so the spout projects far enough into it [8][9]. A floor filler stands beside the tub wherever the tub goes, but it is held only at the floor, so everything that keeps it steady goes under the floor; we cover that in our article on why a floor-mounted tub filler needs a rigid rough-in.

Either way, the filler has to be chosen before the room is finished. A wall filler needs its valve, or its supply stubs, inside the wall before the tile; a floor filler needs its rough-in under the floor before the tile [5][6][8]. Changing your mind afterwards means opening a finished wall or floor — which, in our reading of these instructions, is the real cost of deciding late.

The photograph at the top of this page is ours, from Clearwater: a waterfall spout, a single lever and a hand-shower outlet on one brushed-gold wall plate, with the hose hanging down to the tub.

How high should a wall-mounted tub spout be above the tub rim?

High enough that the lowest point of the spout outlet sits at least 2 inches above the tub’s rim — or 3 inches if the outlet is close to a wall. That is Florida’s air-gap table: an over-rim bath filler with an effective opening of not more than 1 inch needs a minimum air gap of 2 inches away from a wall and 3 inches close to a wall [1]. The air gap is measured vertically from the lowest end of the water outlet to the flood level rim of the fixture it discharges into [1] — for a tub, the edge water would spill over [3].

“Away from a wall” has a definition. The table’s footnote applies the smaller figure only where the nearest wall or obstruction is more than three times the effective opening from the inside edge of the spout opening — four times where two walls meet [1]. The effective opening is not the width of the spout’s mouth: for faucets and similar fittings it is measured at the smallest orifice in the fitting body or in the supply piping to it [3]. So a wide waterfall spout is judged by the smallest passage inside it; where that passage is larger than 1 inch, the gap becomes twice its diameter, or three times close to a wall [1][3].

Kohler draws the spout higher than the code minimum. Its rough-in drawing for its K-302 and K-303 wall-mount bath/shower fittings puts the spout connection a typical 4 inches above the top of the rim, with the valve 8 inches above that in a typical layout, or 4 inches in a bath-only one [5]. Delta’s rough-in for its two-handle wall valve carries a note to check your local plumbing code’s minimum air-gap requirement before the valve is fixed [6].

One trap in the arithmetic: the spout connection in the wall is not the outlet. Most spouts drop a little between the wall and where the water comes out, so the outlet sits lower than the connection — check the drop on your trim’s spec sheet before you fix the valve height. That is our reading of how the drawings are laid out, not a figure from either maker.

How far does a wall-mounted tub spout need to reach?

Far enough past the rim that the stream lands inside the tub, not on the rim or the floor — and that depends on how far the tub sits from the wall. Waterworks’ instructions for its wall-mounted exposed tub fillers say to check the tub’s measurements to make sure the spout projects far enough into it [8][9]. The reach is printed on the spec sheet: 8⅜ inches on its Henry filler and 12⅞ inches on its Dash filler [8][9].

So measure from the finished wall, not the studs: the gap between the wall and the tub, plus the width of the tub’s rim, has to be less than the spout’s reach, with room left for the stream to clear the inside edge. That is our arithmetic, not a manufacturer’s rule — but it is why the tub has to be chosen, and its position on the floor fixed, before the valve goes in.

A freestanding tub set further out than a wall spout can reach is the case for a floor filler, which stands beside the tub instead of reaching to it.

What has to go in the wall before tile for a wall-mounted tub filler?

The valve — or, for an exposed filler, the supply stubs — fixed to the framing, set to a depth measured from the finished wall, connected, flushed and checked for leaks. Delta’s wall-mount trim says plainly that a separate rough-in valve is required and that the valve rough-in must be complete before the trim is installed [7].

Depth is measured from a wall that does not exist yet. Delta’s rough-in puts the front of the stud brace 2¾ inches, plus or minus ½ inch, from the finished wall, and warns that its minimum and maximum roughing-in dimensions are to the finished wall, so tile or any other surface added later must be allowed for [6]. Kohler’s says the same in its own terms: the valve yoke 2¼ inches minimum to 3 inches maximum from its centerline to the outside of the finished wall [5]. Delta’s trim then comes with a short spout shank for finished walls 1/8 to 2 inches thick and a long one for 2 to 3¾ inches [7] — so the thickness of tile, setting bed and backer board has to be known at rough-in.

An exposed wall filler is less forgiving. Waterworks’ Henry needs its hot and cold inlets exactly 8 inches apart — the spread is not adjustable — with the nipples projecting between ½ and 1 inch from the finished wall, and the filler itself on site before rough-in so the installer can check it [8]. Waterworks warns that an inaccurate rough-in will make installation difficult or impossible [8].

Test it while you can still reach it. Delta’s rough-in has the installer pull the plaster guards, flush the valve through the spout shank for at least a minute, and inspect the connections for leaks with the water pressure on, before the guards go back and the wall is finished [6].

Does the hand shower on a tub filler need backflow protection?

Yes. Florida’s code says hand-held showers must conform to ASME A112.18.1/CSA B125.1 and must provide backflow protection in accordance with that standard, or be protected against backflow by a device complying with ASME A112.18.3 [2]. The code also requires plumbing fixture fittings in general to provide backflow protection under A112.18.1, and fittings with hose-connected outlets to conform to A112.18.3 or A112.18.1 [1][2]. The standards it points to are A112.18.1-2018/CSA B125.1-2018, Plumbing Supply Fittings, and A112.18.3, Performance Requirements for Backflow Protection Devices and Systems in Plumbing Fixture Fittings [4].

The reason is the hose. The spout’s air gap only protects the spout; a hand shower on a hose can be dropped into a full tub, below the water line. That is our plain reading of why the code treats it separately. The protection can be built into the fitting: Waterworks’ Henry wall filler has a flow-regulating check valve inside the inlet of the hand shower, and a check valve in the valve body [8].

Ask for it by name when you choose the filler: the spec sheet should say the hand shower meets A112.18.1, or that it carries an A112.18.3 device. If it says neither, it is the wrong part for the job.

What does a floor-mounted tub filler need instead?

A rough-in under the floor in place of the valve in the wall: a mounting plate fixed to the structure, with the supplies coming up through it, set to the thickness of a floor that is not laid yet. How that plate is fixed to wood framing or set into a concrete slab — and why a filler wobbles when it is not — is the subject of our article on why a floor-mounted tub filler needs a rigid rough-in; we do not repeat it here.

The rules about water are the same as for a wall filler. Its spout outlet still needs the 2-inch air gap over the rim (3 inches close to a wall), and its hand shower still needs backflow protection [1][2]. Because the filler stands beside the tub, the spout height is set by the filler you buy rather than by a valve height in the wall — so check the spout height on the spec sheet against the rim height of the tub.

The photograph here is ours: a freestanding tub in Venice with a matte-black floor-mounted filler and hand shower at its side, under a linear wall sconce.

What has to be decided before the wall or floor is closed?

More than most people expect, because each rough-in is set to things that are not there yet. From the instructions we read, these are the ones to settle first:

• Which filler, by model — the trim decides the valve it needs, and an exposed filler’s inlet spread is fixed [7][8]
• Which tub, and exactly where it stands — the spout must reach past its rim [8][9]
• The rim height of the tub, so the spout outlet clears it by at least 2 inches, or 3 inches close to a wall [1]
• The finished wall or floor build-up — tile, setting bed, backer board — because the rough-in depth is measured to the finished surface [5][6][7]
• Whether the hand shower carries the backflow protection the code asks for [2]
• How the hot water at the tub will be held to 120°F — Florida requires bathtub valves to have, or be supplied by, a temperature-limiting device, and Waterworks puts that device on the installer [2][8]

What this means in Clearwater and across Tampa Bay

The Florida Building Code, Plumbing is a statewide code, so the air-gap table, the hand-shower rule and the 120°F limit on bathtub valves apply the same way in Clearwater, Venice, Tampa and the rest of the state [1][2]. The sections quoted here are from the 8th edition (2023).

The photographs on this page are ours: the wall-mounted waterfall filler in Clearwater and the floor-mounted filler in Venice. If you are planning a freestanding tub, call 727-470-7126 with the tub and filler model numbers and the tile you have chosen — the rough-in is set to them.

FAQ

Sources

We review and cite. We do not reproduce a paper or a manual — follow the links for the originals.

1. [1]2023 Florida Building Code, Plumbing, 8th Edition — Chapter 6, §608.2, §608.14.1, §608.16.1 and Table 608.16.1 Minimum Required Air Gaps — Florida Building Commission / International Code Council · 2023Law / code · §608.2: supply lines and fittings installed to prevent backflow; fixture fittings provide backflow protection per ASME A112.18.1/CSA B125.1; §608.14.1: air gap measured vertically from the lowest end of the outlet to the flood level rim, air gaps per ASME A112.1.2; §608.16.1 and Table 608.16.1: over-rim bath fillers with effective openings not greater than 1 in — 2 in away from a wall, 3 in close to a wall; openings over 1 in — two / three times the effective opening; footnote: ‘away from a wall’ where walls are more than three times (one wall) or four times (two intersecting walls) the effective opening from the nearest inside edge of the spout opening. Text read 2026-10-26 via the UpCodes reproduction (up.codes/viewer/florida/fl-plumbing-code-2023/chapter/6).
2. [2]2023 Florida Building Code, Plumbing, 8th Edition — Chapter 4, §405.1, §412.1, §412.2 Hand Showers, §412.5 Bathtub and Whirlpool Bathtub Valves, §412.6 Hose-Connected Outlets — Florida Building Commission / International Code Council · 2023Law / code · §412.2: hand-held showers conform to ASME A112.18.1/CSA B125.1 and provide backflow protection under it, or are protected by a device complying with ASME A112.18.3; §412.5: bathtub valves have or are supplied by a water-temperature-limiting device (ASSE 1070/ASME A112.1070/CSA B125.70) limited to 120°F, or an ASSE 1082/1084 water heater; §412.6: hose-connected outlets conform to A112.18.3 or A112.18.1; §405.1 supply lines installed to prevent backflow. In the Florida edition these are §412, not the §424 of the model IPC. Text read 2026-10-26 via the UpCodes reproduction.
3. [3]2023 Florida Building Code, Plumbing, 8th Edition — Chapter 2, Definitions (Air gap, Effective opening, Flood level rim) — Florida Building Commission / International Code Council · 2023Law / code · air gap: unobstructed vertical distance between the lowest opening of the supplying faucet and the flood level rim; effective opening: minimum cross-sectional area at the point of discharge, as an equivalent circle, measured for faucets at the smallest orifice in the fitting body or the supply piping to it; flood level rim: the edge from which water overflows. Read 2026-10-26 via UpCodes.
4. [4]2023 Florida Building Code, Plumbing, 8th Edition — Chapter 15, Referenced Standards (ASME) — Florida Building Commission / International Code Council · 2023Law / code · A112.18.1-2018/CSA B125.1-2018 Plumbing Supply Fittings (referenced in 412.1, 412.2, 608.2 and others); A112.18.3M-2002 (R2022) Performance Requirements for Backflow Protection Devices and Systems in Plumbing Fixture Fittings (412.2, 412.6); A112.1.2-2022 Air Gaps in Plumbing Systems (608.14.1). The standards themselves are paid documents and were not read; we cite only what the code says about them. Read 2026-10-26 via UpCodes.
5. [5]Two-Valve and Three-Valve Wall-Mount Bath/Shower Fitting K-302, K-303, K-6934 — Installation and Care Guide 1205552-2-A — Kohler Co. · undatedManufacturer's manual · p. 3 rough-in drawing: spout connection 4 in typical above the top of the rim; valve yoke 8 in typical above the spout, 4 in for bath only; pp. 4–7: rough-in the supply yoke 2¼ in minimum to 3 in maximum from its centerline to the outside of the finished wall unless the trim instructions say otherwise. One maker’s example, not necessarily the brand on our jobs. PDF read 2026-10-26.
6. [6]R3500-WL Rough-In for Two Handle Wall Mounted Faucet — instruction sheet 86642 Rev. F — Delta Faucet Company · 2023Manufacturer's manual · dated 02/22/2023; p. 2: check local plumbing code minimum air-gap requirements before fixing the valve; front of the stringer 2¾ in ± ½ in from the finished wall; min/max dimensions are to the finished wall, and tile added later must be considered; flush through the spout shank for at least a minute and inspect for leaks with the water pressure on, then refit the plaster guards; p. 3: finish wall with 1½-in holes. The sheet is titled for a wall-mounted lavatory faucet; Delta’s T5797-WL tub filler trim requires this same rough-in [7]. PDF read 2026-10-26.
7. [7]T5797-WL Two Handle Wall Mounted Tub Filler Faucet Trim — instruction sheet 102432 Rev. A — Delta Faucet Company · 2018Manufacturer's manual · dated 4/03/2018; p. 1: rough-in R3500-WL required; complete the valve rough-in before installing the trim; p. 2: short spout shank for finished walls 1/8–2 in thick, long shank for 2–3¾ in; flush the system. PDF read 2026-10-26.
8. [8]Henry / Henry Chronos Wall Mounted Exposed Tub Filler with Handshower — Installation Guidelines — Waterworks · 2025Manufacturer's manual · updated 3.27.2025; p. 1: on site before rough-in to verify the 8-in inlet spread, which is not adjustable; check tub measurements so the spout projects far enough into the tub; temperature-limiting device to ASSE 1070 is the installer’s responsibility; spout reach 8⅜ in; p. 2: an inaccurate rough-in makes installation difficult or impossible; ¾-in NPT nipples project ½–1 in from the finished wall; p. 4: flow-regulating check valve inside the hand-shower inlet; turn on water and check for leaks; p. 5: check valve in the valve body. PDF read 2026-10-26.
9. [9]Dash Wall Mounted Exposed Tub Filler with Metal Handshower — Installation Guidelines — Waterworks · 2025Manufacturer's manual · updated 11.17.2025; p. 1: check tub measurements so the spout projects far enough into the tub; spout reach 12⅞ in; 8-in inlet spread not adjustable; supply lines project at least 2¼ in from the finished wall. PDF read 2026-10-26.