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 from the finished wall behind the toilet to the center of the drain (closet flange).
| Measurement | FPC/IPC Minimum | Recommended |
|---|---|---|
| Rough-in distance (wall to flange center) | 12" (10" or 14" for specific toilets) | 12" |
| Centerline from side wall (min) | 15" — FPC §405.3.1 | 18" / ADA: 18" |
| Centerline from opposite fixture/wall | 15" — FPC §405.3.1 | 18" |
| Clear floor space in front | 21" min — FPC §405.3.1 | 30" |
| Closet flange height | Top 0"–1/4" above finished floor | Flush + wax ring |
| Drain pipe size (closet bend) | 3" min — FPC §708.1 | 4" at main stack |
| Drain slope | 1/4" per foot min — FPC §704.1 | 1/4" per foot |
| Vent distance (trap to vent) | ≤ 6 ft — FPC §909.1 | As short as practical |
FL-specific: FL homes often have 10" rough-in toilets in smaller guest bathrooms built 1960s–1980s. Measure back wall to flange center BEFORE purchasing — a 12" toilet on a 10" rough-in will hit the wall.
Shower Drain Placement — FPC §408 / §417
| Measurement | FPC Requirement |
|---|---|
| Drain size — shower up to 1,296 sq in | 2" min — §417.5.2.2 |
| Drain size — shower over 1,296 sq in | 3" min — §417.5.2.2 |
| Min shower floor size | 30"×30" — §417.4 |
| ADA roll-in floor | 60"×30" — ADA §608.3 |
| Floor slope | 1/4" per foot to drain — §417.5.2 |
| Trap to vent (2" drain) | ≤ 5 ft — §909.1 |
| Shower valve rough-in height | 48"–52" AFF |
| Showerhead rough-in height | 78"–80" AFF — §417.6 |
Pre-slope critical: In FL slab homes the shower drain area requires a pre-slope (mud bed) at 1/4" per foot. Mark the drain center on the slab BEFORE the mud bed is poured.
Bathtub Rough-In — FPC §405 / §408
Standard 5' tub: 60" length, 30"/32" width. Drain rough-in ~3.5"–4" from end wall, 16" from back wall for 32" tub. Overflow 17"–20" AFF. Drain pipe 1-1/2" min (tub only). Valve 28"–30" AFF. Hot on LEFT (per ASSE 1016).
Vanity / Sink Drain Rough-In — FPC §405 / IPC §405.3
Drain rough-in height standard vanity 18"–20" AFF (20" ideal). Vessel/tall vanity 22"–24" AFF. ADA sink 17" max AFF. Hot supply 4" left of drain CL, cold 4" right. Supply stub-out 20"–22" AFF, 1/2" IPS. Drain 1-1/4" trap, 1-1/2" stub.
FL humidity tip: Ensure the P-trap is accessible for cleaning (traps collect soap scum faster in humid climates). Set the trap arm with a cleanout-accessible configuration to combat biofilm smell.
FL Bathroom Clearance Requirements
- Toilet centerline to side wall: FPC min 15", preferred 18", ADA 18" (grab bar side). ADA needs 60" clear floor space.
- Toilet clear space in front: FPC min 21", preferred 30". ADA 60" forward / 56" side transfer.
- Shower min interior: FPC min 30"×30" (§417.4); practical min 36"×36". ADA roll-in 60"×30"; transfer 36"×36".
- Lavatory clear space: FPC min 21" in front; ADA 30"×48". ADA rim ≤34" AFF.
- Bathroom door clear width: FBC min 24"; preferred/ADA 32".
- Fixture-to-fixture: Toilet to lavatory 15" min from CL; lavatory to side wall 4" min; two lavatories 30" min center-to-center; bathtub to wall 0" (alcove).
FL bathroom size reality: many 1960s–1980s S FL concrete block homes have master bathrooms just 5'×8'. Focus clearances on toilet and shower — where FL inspectors focus.
FL Bathroom Vent Stack Guide
Venting is the most critical and most frequently violated aspect of bathroom plumbing in Florida. FL humidity makes sewer gas odors more noticeable; slab construction means a venting error after the pour requires cutting concrete. Common FL violation: a cheater vent (AAV) in a sealed cabinet or attic with no air source.
Trap-to-Vent Distance Limits — FPC §909.1
| Drain Pipe Size | Max Trap-to-Vent Distance | Common Use |
|---|---|---|
| 1-1/4" | 5 ft | Lavatory / sink |
| 1-1/2" | 6 ft | Lavatory, tub, small shower |
| 2" | 8 ft | Shower, laundry, floor drain |
| 3" | 12 ft | Toilet (closet flange) |
| 4" | 12 ft | Main drain / soil stack |
Vent Pipe Sizing — FPC §904 / §916
| Vent Type | Minimum Size | FL Rule |
|---|---|---|
| Individual toilet vent | 2" — §904.1 | Many FL jurisdictions require 3" |
| Individual lavatory vent | 1-1/4" | Typically 1-1/2" in practice |
| Shower individual vent | 1-1/2" | Often 2" in FL |
| Common bathroom vent | ≥ largest individual | Typically 3" |
| Main stack | 4" (serving toilets) | 3" only if no toilet connected |
| Stack above roof | 4" — §904.2 (6" above roof) | Inspect storm collar in wind zones |
Wet Venting — FPC §908
A single pipe serves as both drain and vent — common in FL bathrooms. The lavatory drain serves as drain and vent for the toilet, connecting downstream of the toilet trap, then extending up through the wall and roof. Rules: wet-vented fixtures above flood rim of others; pipe sized as drain AND vent (min 2" for toilet wet vent); max 1 toilet per wet vent. Most common config: toilet 3" drain → wet vent connection → lavatory 1.5" drops in → 2" wet vent up through wall → roof at 4" min above surface.
Air Admittance Valves (AAV) in Florida — FPC §918
Florida permits AAVs (Studor vents) as an alternative. Rules: must be ASSE 1051/1050 listed; located where it receives air; accessible for maintenance; min 4" above trap arm; can serve fixtures/branch but building main vent must still extend through roof. Cannot replace main building vent. Should not be used in beach/high-humidity environments where mechanism corrodes. Some jurisdictions (Miami-Dade, Broward) have stricter AAV restrictions.
Vent Through Roof — FL-Specific Requirements
- Vent must extend min 6" above roof (FPC §904.2); flash/seal with storm collars rated for FL.
- HVHZ (Miami-Dade, Broward) require NOA-compliant roof flashing for all vent penetrations.
- Terminate with screen/mesh cap to prevent palmetto bug/insect entry.
- In tile roof construction, coordinate vent location with the tile installer.
Bathroom Rough-In — FL By the Numbers
| Rough-In Fact | FL Reality |
|---|---|
| Most common toilet rough-in (1990–present) | 12 inches |
| Most common toilet rough-in (pre-1980) | 10 inches (measure first!) |
| Standard FL shower (new construction) | 48"×36" or 36"×36" |
| Primary vent failure in FL additions | Exceeding trap-to-vent distance |
| FL inspection failure rate — bathroom rough-in | ~15–20% first-time (venting/slope) |
| Cost to re-route drain under FL slab | $800–$3,500 |
| Average FL plumber cost full bathroom rough-in | $1,500–$4,000 (no fixtures) |
| Time from rough-in to inspection pass | 3–7 business days |
Most expensive FL mistake: Setting the toilet flange too high or too low. In FL slab construction the flange is set during the rough-in pour — fixing it requires cutting the slab. Use a flange extension spacer kit to fine-tune height after tile rather than relying on exact rough-in height.