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FL Bathroom Rough-In Calculator

Florida Plumbing Code (FPC) Chapter 4 compliant · Toilet · Shower · Vanity · Vent Stack · ADA Clearances

FPC §403 · §405 · §408 · §411 · IPC Table 405.3.1 · ADA Standards §603
📐Bathroom Rough-In Measurements
Select the fixture and slab/wall type to generate code-compliant rough-in measurements per Florida Plumbing Code (FPC), which adopts the International Plumbing Code (IPC) with Florida amendments.
📋FPC Rough-In Reference — All Fixtures
🚽 Toilet (Floor-Mount) FPC §405.3.1 / IPC Table 405.3.1
The "rough-in distance" for a toilet is the measurement from the finished wall behind the toilet to the center of the drain (closet flange). This is the most common source of error in bathroom rough-ins.
MeasurementFPC / IPC MinimumRecommended
Rough-in distance (wall to flange center)12" (standard), 10" or 14" for specific toilets12" (most toilets)
Centerline from side wall (minimum)15" — FPC §405.3.118" preferred / ADA: 18"
Centerline from opposite fixture/wall15" — FPC §405.3.118" preferred
Clear floor space in front of toilet21" minimum — FPC §405.3.130" preferred
Closet flange height (finished floor)Flange top 0"–1/4" above finished floorFlush with finished floor + wax ring allowance
Drain pipe size (closet bend)3" minimum — FPC §708.14" at main stack connection
Drain slope (closet drain to stack)1/4" per foot minimum — FPC §704.11/4" per foot
Vent distance (trap to vent)≤ 6 feet — FPC §909.1As short as practical
FL-specific: Florida homes often have 10" rough-in toilets in smaller guest bathrooms built in the 1960s–1980s. When replacing in an existing bathroom, measure from the back wall to the center of the flange BEFORE purchasing a new toilet — buying a 12" toilet for a 10" rough-in will cause the tank to hit the wall.
🚿 Shower Drain Placement FPC §408 / FPC §417
Shower drain placement must be centered in the shower floor or positioned per the linear drain manufacturer's specification for linear drains. Key measurements for new shower rough-in:
MeasurementFPC Requirement
Drain size — shower up to 1,296 sq in floor area2" minimum — FPC §417.5.2.2
Drain size — shower over 1,296 sq in3" minimum — FPC §417.5.2.2
Minimum shower floor size (FPC)30" × 30" — FPC §417.4
Standard shower floor size (recommended)36" × 36" minimum practical
ADA shower floor size (roll-in)60" × 30" minimum — ADA §608.3
Drain slope of shower floor1/4" per foot to drain — FPC §417.5.2
P-trap depth below drain2" drain trap, 2" outlet — FPC §1002.2
Trap to vent distance (2" drain)≤ 5 feet — FPC §909.1
Drain rough-in height from subfloorVaries by finish floor height — set so drain cover is flush with tile
Shower valve rough-in height (mixing valve)48"–52" AFF (above finished floor), code minimum — manufacturer may vary
Showerhead rough-in height78"–80" AFF — FPC §417.6 allows variation
Pre-slope critical: In FL slab homes, the shower drain area requires a pre-slope (mud bed) under the tile liner. The pre-slope must run from the walls down to the drain at 1/4" per foot. This is set before the waterproofing membrane and tile. Measure and mark the drain center point on the slab BEFORE the mud bed is poured — moving it after is extremely difficult.
🛁 Bathtub Rough-In FPC §405 / FPC §408
Standard 5' alcove bathtub rough-in measurements. The tub drain is always at the foot end of the tub (plumbed end).
MeasurementValue
Standard 5' tub overall length60" (5'0")
Standard tub width (alcove)30" or 32"
Drain rough-in from back wallFrom back wall to drain center: verify by tub model — typically 3.5"–4" from end wall, 16" from back wall for 32" wide tub
Overflow rough-in height17"–20" AFF to overflow center — varies by tub
Drain pipe size1-1/2" minimum (tub only) — FPC §702.1; 1-1/2" to 2" if combined with shower
Tub/shower valve rough-in height28"–30" AFF for tub-only valve
Diverter (if shared tub/shower) rough-in heightSame as valve — 28"–32" AFF; showerhead at 78"–80"
Hot supply location (left or right)Hot on LEFT (plumber's left when facing valve) — per ASSE 1016
🚰 Vanity / Sink Drain Rough-In FPC §405 / IPC §405.3
Vanity drain rough-in height is the most commonly wrong measurement in bathroom renovations. Set it wrong and you'll need a modified P-trap or an extension.
MeasurementValue
Drain rough-in height (center of drain stub) — standard vanity18"–20" AFF — most vanity-top sinks: 20" AFF is ideal for standard 32"–34" vanity height
Drain rough-in height — vessel sink / tall vanity22"–24" AFF to allow trap arm connection above P-trap crown
ADA sink drain rough-in height (accessible)17" maximum AFF for ADA sink clearance — ADA §606.2
Drain lateral position (centered on sink)Centered on vanity cabinet, typically 12"–16" from side wall depending on vanity width
Drain pipe size — single lavatory sink1-1/4" trap, 1-1/2" drain stub — FPC §702.1
Hot supply rough-in — horizontal offset4" left of drain centerline
Cold supply rough-in — horizontal offset4" right of drain centerline
Supply stub-out height (under-sink)20"–22" AFF — allows angle stop valve access under vanity
Supply stub-out size1/2" IPS — FPC §604.4
FL humidity tip: In Florida bathrooms, ensure the P-trap is accessible for cleaning (traps collect soap scum faster in humid climates). When roughing in the drain, set it so the trap arm extends through the wall and terminates with a cleanout-accessible configuration. Many FL vanities get smelly from biofilm — a trap with a cleanout makes maintenance much easier.
📏FL Bathroom Clearance Requirements
Enter your bathroom dimensions to check clearance compliance against FPC §405.3.1, IPC Table 405.3.1, and ADA Standards §603 (for accessible bathrooms):
📐FPC Minimum Clearance Requirements
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Toilet — Centerline to Side Wall / Fixture
FPC minimum: 15" from toilet centerline to side wall or adjacent fixture. Preferred: 18". ADA requirement: 18" from toilet centerline to side wall (grab bar wall side). Note: FPC §405.3.1 sets the 15" minimum — it is legal but very tight. Most experienced plumbers and inspectors will flag 15" as "technically passing but inadequate." ADA requires 60" minimum clear floor space around the toilet for accessible use.
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Toilet — Clear Space in Front (Depth)
FPC minimum: 21" in front of toilet from front edge of bowl to opposite wall or obstruction. Preferred: 30". ADA requirement: 60" depth for forward approach OR 56" for side transfer. The 21" minimum makes a very tight powder room — acceptable for code but uncomfortable for daily use.
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Shower — Minimum Interior Dimensions
FPC minimum: 30" × 30" (FPC §417.4). Note: a 30"×30" shower is barely functional — most FL plumbers and contractors won't install this size. Practical minimum: 36"×36". ADA roll-in shower: 60"×30" minimum. Transfer shower (ADA): 36"×36". Standard FL shower (comfortable): 42"×42" or 48"×36".
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Lavatory / Vanity — Clear Space
FPC minimum: 21" clear space in front of lavatory. For an accessible/ADA vanity, 30"×48" clear floor space is required (ADA §606.2). The lavatory rim may not exceed 34" AFF (ADA). Standard residential vanity: no code minimum on vanity face height beyond the 21" floor clearance requirement.
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Bathroom Door Clear Width
FBC minimum: 24" clear width for interior doors serving bathrooms in residential occupancies. Preferred: 32" clear. ADA requirement: 32" minimum clear width. Standard door size for 32" clear: 34" door in a 36" rough opening. Note: Clear width is measured from the face of the door to the face of the door stop, not the rough opening.
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Fixture-to-Fixture Clearances
Between toilet and lavatory: 15" minimum from toilet centerline to side of lavatory (FPC §405.3.1).
Between lavatory and side wall: 4" minimum from sink edge to side wall (IPC Table 405.3.1).
Between two lavatories: 30" minimum center-to-center (IPC Table 405.3.1).
Bathtub to wall: 0" permitted (alcove), but shower fixtures need 6" clearance side walls.
FL bathroom size reality: Many FL homes (especially 1960s–1980s South FL concrete block construction) have extremely small master bathrooms — some just 5' × 8' (60" × 96"). Code permits this size for a full bathroom but it is very tight. When renovating these spaces, focus clearances on the toilet and shower — those are where FL inspectors focus. Vanity clearances rarely fail.
🔧FL Bathroom Vent Stack Guide
Venting is the most critical and most frequently violated aspect of bathroom plumbing in Florida. Proper venting prevents siphoning of P-traps, eliminates sewer gas in occupied spaces, and is a primary inspection item. FPC §9 governs all vent requirements:
Why Bathroom Venting Is Critical in FL
In Florida, two factors make proper bathroom venting even more important than in cooler climates: (1) Humidity: FL's high humidity makes sewer gas odors more noticeable — and more rapidly spread throughout a home when traps are siphoned. (2) Slab construction: Most FL homes are slab-on-grade, meaning drain lines run under the slab and cannot be easily accessed for repair. A venting error discovered after the slab is poured means cutting concrete. Rough-in inspection ensures venting is correct before the slab is poured or walls are closed.

Common FL violation: Installing a "cheater vent" (air admittance valve) in a location that doesn't meet FPC requirements — typically in a closed cabinet with no air source, or in an attic space that doesn't connect to open air.
Trap-to-Vent Distance Limits FPC §909.1
The maximum horizontal distance from the trap weir (bottom of the trap outlet) to the vent is critical — exceed these limits and the vent won't prevent trap siphoning:
Drain Pipe SizeMax Trap-to-Vent DistanceCommon Use
1-1/4"5 feetLavatory / sink
1-1/2"6 feetLavatory, tub, shower (small)
2"8 feetShower, laundry, floor drain
3"12 feetToilet (closet flange)
4"12 feetMain drain / soil stack
Common mistake: When adding a bathroom far from the main vent stack, plumbers sometimes exceed the trap-to-vent distance without adding an individual vent. This causes gurgling toilets, slow drains, and sewer gas — often misdiagnosed as a drain clog. The actual fix is adding a proper vent connection.
Vent Pipe Sizing FPC §904 / FPC §916
Vent TypeMinimum SizeFL Rule
Individual toilet vent2" — FPC §904.1Many FL jurisdictions require 3" vent for toilet regardless of code minimum
Individual lavatory vent1-1/4" — FPC §904.1Typically 1-1/2" in practice
Shower individual vent1-1/2" — FPC §904.1Often 2" in FL for larger showers
Common (shared) bathroom ventMust equal or exceed largest individual vent requirementTypically 3" for full bathroom
Main stack (soil + vent)4" — FPC §904.1 for stacks serving toilets3" permitted only if no toilet is connected (lavatory/shower only stack)
Stack above roof penetration4" — FPC §904.2 (extends 6" above FL roofs min.)In FL wind zones, inspect storm collar carefully — improperly sealed roof vents are a common water intrusion source
Wet Venting — A Common FL Bathroom Solution FPC §908
Wet venting allows a single pipe to serve as both a drain and a vent simultaneously — very common in FL bathrooms where running a separate vent stack would require penetrating through multiple floors or a long horizontal run under the slab.

How wet venting works in a Florida bathroom: The lavatory (sink) drain serves as both a drain and a vent for the toilet. The lavatory drain connects to the toilet drain downstream of the toilet trap, and the lavatory vent pipe then extends up through the wall and through the roof. The lavatory provides adequate air to prevent siphoning of both the toilet and lavatory traps.

FL wet venting rules (FPC §908): Wet-vented fixtures must be above the flood rim level of other wet-vented fixtures. The wet vent pipe must be sized as a drain (for the total fixture units flowing through it) AND as a vent (minimum 2" for wet vent serving a toilet). Maximum 1 toilet per wet vent system. The wet vent must be installed horizontally and cannot drop below the flood rim of any fixture it serves.

Most common FL wet vent configuration: Toilet connects to 3" drain → 3" drain runs to wet vent connection → lavatory (1.5") drain drops into wet vent pipe → wet vent continues as 2" pipe up through wall → exits roof at 4" minimum above roof surface.
Air Admittance Valves (AAV) in Florida FPC §918
Florida DOES permit Air Admittance Valves (AAV, sometimes called Studor vents or cheater vents) under FPC §918 as an alternative to a conventional vent pipe. Critical FL rules for AAV use:

✓ AAV must be listed to ASSE 1051 or ASSE 1050 (individual fixture AAV must be ASSE 1051)
✓ AAV must be located in a space that receives air — an AAV in a completely sealed cabinet space will not function
✓ AAV must be accessible for maintenance and inspection — cannot be buried in a wall
✓ AAV must be installed minimum 4" above the trap arm connection (the horizontal drain pipe)
✓ AAV can serve individual fixtures or a branch — but the building main vent must still extend through the roof
✗ AAV cannot replace the main building vent — at least one vent must extend to open air per FPC §918.7
✗ AAV should not be used in beach/high-humidity environments where the valve mechanism can corrode

FL code note: Some FL jurisdictions (notably Miami-Dade and Broward) have stricter-than-state-code AAV restrictions. Verify with your local building department before planning an AAV-based vent system.
Vent Through Roof — FL-Specific Requirements
Florida's climate creates unique roof vent requirements:

• Vent pipe must extend minimum 6" above the roof surface (FPC §904.2). In FL wind zones (most of South FL), flash and seal all roof vent penetrations with appropriate storm collars and sealant rated for FL conditions.
• HVHZ (High Velocity Hurricane Zone) — Miami-Dade and Broward — require NOA (Notice of Acceptance) compliant roof flashing for all vent penetrations. Use only NOA-approved lead, aluminum, or rubber roof jacks.
• FL vent pipes must terminate with a screen or mesh cap to prevent insect and bird entry — particularly important in South FL where palmetto bugs (American cockroaches) regularly enter homes through open vent stacks.
• In FL tile roof construction, coordinate vent stack location with the tile installer — running a 4" vent between tile courses after tile is installed is extremely disruptive and expensive.
🔧Get a Florida Licensed Plumber
Bathroom rough-in work requires a FL licensed plumbing contractor (CFC license). We verify all FPC compliance requirements, obtain required permits, and schedule inspections — so your new bathroom starts right and passes first time.
✓ FL licensed Master Plumber (MP license) · Permit application handling · All inspections coordinated · Rough-in drawings provided · ADA / accessible bathroom design available · FPC Chapter 4 compliance guaranteed
📊Bathroom Rough-In — FL By the Numbers
Rough-In FactFL Reality
Most common toilet rough-in in FL (built 1990–present)12 inches (standard)
Most common toilet rough-in in FL (built pre-1980)10 inches (measure before replacing!)
Standard FL shower size (new construction)48" × 36" (comfortable) or 36" × 36" (code minimum + some margin)
Primary vent failure in FL bathroom additionsExceeding trap-to-vent distance (especially when slab is poured too far from main stack)
FL inspection failure rate — bathroom plumbing rough-in~15–20% first-time failure (primarily venting and slope issues)
Cost to re-route drain under FL slab if roughed-in incorrectly$800 – $3,500 (jackhammer, re-pipe, concrete restoration)
Average FL licensed plumber cost for full bathroom rough-in$1,500 – $4,000 (not including fixtures)
Time from rough-in to inspection pass (FL average)3–7 business days after calling for inspection
The most expensive FL bathroom plumbing mistake: Setting the toilet flange too high (above finished floor level) or too low (creating a void that allows wax ring failure). In FL slab construction, the flange is set during the rough-in pour — if it's wrong, fixing it requires cutting the slab. Always use a flange extension spacer kit to fine-tune height after tile is installed rather than relying on exact rough-in height.
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Florida Quick Answers

How much does bathroom rough in cost in Florida?

On this page, Florida bathroom rough in estimates run about $1,500-$4,000, depending on home size, materials, and project scope. Use the calculator above for a Florida-specific estimate.

What affects the price?

Pricing depends on the size and layout of your home, the pipe materials and fixtures you choose, your Florida region and local labor rates, and permit fees. Work that is more complex or harder to access generally costs more.

Can I DIY this, or should I hire a licensed plumber?

In Florida, minor maintenance may be DIY, but anything beyond that generally calls for a licensed plumber, and many jobs require a permit and inspection. When a permit, gas work, or your main water or drain lines are involved, hire a Florida-licensed plumber.

Does homeowners insurance cover it?

It depends on the cause and your specific policy. Sudden, accidental damage is more often covered than gradual wear-and-tear or maintenance - confirm the details with your insurer.

How long does it take?

Timelines depend on scope - many routine jobs take a few hours to a day, while larger projects run longer. Your licensed plumber can confirm after assessing your home.

Plan with confidence

Planning estimate, not a quote — confirm with a licensed Florida plumber. Confidence is qualitative: ranges reflect this page’s Florida assumptions, not a guaranteed price.

Key assumptions

Estimates on this page are Florida-specific and reflect Bathroom Rough In Calc for typical Florida homes.

From this page: On this page, Florida bathroom rough in estimates run about $1,500-$4,000, depending on home size, materials, and project scope. Use the calculator above for a Florida-specific estimate.

Your actual cost depends on your home's condition, layout, and local labor and permit rates.

Factors that raise or lower cost

From this page: Pricing depends on the size and layout of your home, the pipe materials and fixtures you choose, your Florida region and local labor rates, and permit fees. Work that is more complex or harder to access generally costs more.

Generally raises cost: harder access, older homes, added permits and inspections, premium fixtures or materials, and emergency or after-hours work.

Generally lowers cost: easy access, bundling several items in one visit, standard fixtures, and off-peak scheduling.

Preparation checklist

  • Clear access to the work area and locate your main and fixture shut-off valves.
  • Check with your county or city building department (AHJ) on whether a permit and inspection are required.
  • Note the make, model, or measurements of existing fixtures and pipe materials.
  • Get the scope, total price, warranty, and cleanup terms in writing before work starts.
  • Verify the plumber holds an active Florida license and carries insurance.

Questions to ask your plumber

  • Are you licensed and insured in Florida, and who pulls the permit?
  • Is the quote itemized for parts, labor, permit fees, and disposal?
  • What could change the final price once the work begins?
  • What warranty covers the parts and the labor?
  • How long will the job take, and will my water be shut off?
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Last reviewed: July 1, 2026 (US Eastern)

Reviewed by the FL Plumbing Tools editorial team.

Sources: Florida plumbing cost research and Florida Building Code / local authority-having-jurisdiction (AHJ) permit references.

Florida reference: Estimates and guidance reflect Florida labor rates, permitting, hard water, humidity, and coastal conditions.

Updates: Reviewed periodically and updated as Florida codes, permit fees, and market rates change.