🔴 FL DWV Drain Sizing & Slope Calculator

FPC Table 709.1 fixture units, horizontal drain sizing, trap arm limits, and slope drop

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🔢 Fixture Unit Counter (FPC Table 709.1)

Count fixtures on this drain branch — DFU values auto-populate.

Total Drain Fixture Units (DFU) 0 DFU

Drain Sizing Results

🔍 Trap Arm Length Checker

Trap Size (inches)

Actual Arm Length (ft)

📐 Drain Capacity Reference (FPC Table 710.1)

Pipe Size	1/8" slope	1/4" slope	1/2" slope
1½"	1 DFU	3 DFU	5 DFU
2"	8 DFU	14 DFU	21 DFU
2½"	24 DFU	42 DFU	—
3"	48 DFU	84 DFU	—
4"	144 DFU	250 DFU	—
5"	240 DFU	425 DFU	—
6"	400 DFU	700 DFU	—
8"	1,100 DFU	1,920 DFU	—

📏 Drain Slope & Drop Calculator

Pipe Run Length (feet) Drain Slope Pipe Size FL County (for elevation/local notes)

Slope Results

💨 Vent Sizing Reference (FPC Table 916.1)

FPC 904.1: Every trap and trapped fixture shall be vented.

FPC 906.1 — Vent pipe minimum size: Shall not be less than 1¼" and not less than ½ the diameter of the drain it serves.

FPC 916.1 — Individual vent sizes:

Drain Size	Min Vent	Max DFU on Vent	Max Vent Length
1¼" drain	1¼"	1 DFU	45 ft
1½" drain	1¼"	4 DFU	60 ft
2" drain	1½"	10 DFU	120 ft
3" drain	2"	30 DFU	180 ft
4" drain	3"	100 DFU	212 ft
5"+ drain	4"	300+ DFU	300 ft

FPC 903.1 — FL roof vent termination: Vent shall extend min 6" above roof in FL. In Miami-Dade/Broward HVHZ, vent flashing must be product-approved per FL Building Code 1714.5.

FPC 908 — Wet venting: Permitted in FL for single bathroom groups. 2" wet vent serves 1–3 fixtures; 3" wet vent serves up to 6 fixtures. Common in FL slab construction.

📋 FPC DWV Code — Key Requirements

FPC Chapter 7 — Sanitary Drainage

FPC 701.1 — Scope: DWV system shall convey sewage and liquid wastes to public sewer or approved private disposal system. FL requires FL-licensed plumbing contractor for all DWV work.

FPC 704.1 — Slope: Horizontal drainage piping shall be run in practical alignment and a uniform slope of not less than ¼ unit vertical per foot (2%) for pipes 3" and smaller. Pipes 4" and larger may be sloped at ⅛" per foot minimum (1.04%).

FPC 704.2 — Minimum size: No horizontal waste or soil pipe shall be smaller than the largest trap discharge it serves. Minimum 3" for water closets and urinals.

FPC 704.3 — Change of direction: Horizontal-to-vertical changes shall use 45° wyes or combo fittings. No 90° sanitary tees in horizontal-to-horizontal runs. No double sanitary tees.

FPC 707.1 — Prohibited fittings: Prohibited in DWV: running traps, double-hub fittings used backwards, bell-and-spigot on PVC without approved coupling, copper fittings with lead joints.

FPC Chapter 9 — Vents

FPC 901.1 — Venting required: Every trap and trapped fixture shall be vented in accordance with this chapter.

FPC 904.1 — Air admittance valves (AAV): Permitted in FL under FPC 918 for individual fixtures and branch vents. AAVs prohibited as the only vent on a drainage stack. Must be accessible and installed per ASSE 1051 (island fixtures) or ASSE 1049.

FPC 909.2 — Trap arm lengths (max distance from trap to vent):

Trap Size	Max Trap Arm	Slope Required
1¼"	2.5 ft	¼" per foot
1½"	3.5 ft	¼" per foot
2"	5.0 ft	¼" per foot
3"	6.0 ft	¼" per foot
4" and larger	10.0 ft	⅛" per foot

DWV Inspection Checklist

All horizontal drains sloped ¼" per foot (3" and smaller) FPC 704.1 — ⅛" per foot minimum for 4"+ pipe; verify with string line and level

No prohibited fitting types in DWV system FPC 704.3 — no 90° Ts on horizontal runs; use 45° wyes and combo fittings for direction changes

Water closet drain minimum 3" diameter FPC 704.2 — no WC shall drain into pipe smaller than 3"; all WCs require 3" minimum

Trap arm lengths within FPC 909.2 maximum limits 1½" max 3.5 ft; 2" max 5 ft; 3" max 6 ft; 4"+ max 10 ft

Every trap and fixture properly vented FPC 901.1/904.1 — all fixtures vented; AAVs allowed per FPC 918 with access panel

Vent pipe minimum ½ of drain diameter (min 1¼") FPC 906.1 — vent can never be smaller than 1¼" or less than ½ the drain pipe size

Cleanouts installed per FPC 708 — max 100 ft spacing FPC 708.4 — cleanout required every 100 ft on horizontal runs; at each 90° change of direction

DWV pressure test (air or water) before covering FPC 312.2 — 5-psi air test or 10-ft water head; FL inspectors typically require rough-in inspection before slab pour

FL plumbing permit pulled for all DWV work FBC 105.1 — permit required for all new DWV installation and major alterations in FL

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florida DWV drain sizing calculator, FPC table 709.1 fixture units florida, drain fixture units florida plumbing code, horizontal drain sizing florida, FPC table 710.1 drain capacity, trap arm length florida, FPC 909.2 trap arm, drain slope calculator florida, 1/4 inch per foot slope florida, drain vent sizing florida, FPC chapter 7 sanitary drainage, fixture unit count florida plumbing, DWV pipe sizing florida, floor drain sizing florida, toilet drain size florida 3 inch, kitchen drain sizing florida, bathroom group drain florida, FPC 704.1 drain slope, wet venting florida, air admittance valve florida AAV, DWV rough-in florida slab, drain inspection florida, plumbing permit DWV florida, FPC chapter 9 vents florida, vent stack sizing florida, vent pipe minimum diameter florida FPC Table 709.1 fixture unit values: bathtub or shower 2 DFU; bathroom sink lavatory 1 DFU; bidet 1 DFU; clothes washer 2 DFU; dishwasher 2 DFU; floor drain 2 DFU; kitchen sink 2 DFU; laundry tub 2 DFU; mop sink service sink 3 DFU; toilet water closet flush tank 4 DFU; toilet water closet flush valve 6 DFU; urinal 4 DFU; drinking fountain 0.5 DFU; emergency floor drain 0 DFU FPC Table 710.1 horizontal drain capacity: 1.5 inch pipe at 1/8 slope 1 DFU at 1/4 slope 3 DFU; 2 inch pipe at 1/8 slope 8 DFU at 1/4 slope 14 DFU; 3 inch pipe at 1/8 slope 48 DFU at 1/4 slope 84 DFU; 4 inch pipe at 1/8 slope 144 DFU at 1/4 slope 250 DFU; 6 inch pipe at 1/8 slope 400 DFU at 1/4 slope 700 DFU FPC 909.2 trap arm max lengths: 1.25 inch trap max 2.5 feet; 1.5 inch trap max 3.5 feet; 2 inch trap max 5 feet; 3 inch trap max 6 feet; 4 inch trap max 10 feet; all at 1/4 inch per foot slope; trap arm is distance from trap weir to vent Florida DWV pipe materials approved FPC chapter 6: PVC DWV schedule 40 ASTM D2665; ABS DWV ASTM D2661; cast iron hub and spigot CISPI 301; cast iron hubless CISPI 301; copper DWV ASTM B306; galvanized steel ASTM A53 existing only; PEX not approved for DWV in florida; CPVC not approved for DWV in florida FL slab construction DWV: under-slab inspection required before pour in most FL counties; rough-in inspection separate from final inspection; Miami-Dade requires separate MEP inspections; no PVC exposed above ground unless UV-rated or protected; cleanout required at or near foundation per FPC 708.5