Florida Roof Drainage Requirements for Type B Deck Roofs
The Florida Building Code requires primary roof drains, secondary (overflow) drainage, and a structural check that the roof can't pond water and overload itself. On a Type B deck roof, slope comes from sloped framing or tapered insulation, and the drains sit in sump pans set into the deck. We supply the deck and sump pans: recessed is standard, sloped when specified.
What the code asks for
- Primary drains sized for the design rainfall.
- Secondary drains or scuppers in case the primary system clogs.
- A minimum roof slope for the roof covering.
- Structural design for rain load and ponding instability.
How Type B deck fits in
Type B is usually flat on sloped framing, or flat on level framing with tapered insulation creating the slope. Deck deflection matters because a flexible roof sags, collects water and sags further. That is why the engineer checks deflection; the catalog gives service loads at L/240 with factors for other limits. Frame drain openings so the deck is supported around them.
Order drainage accessories with the deck
Accessories ship in 10' lengths and only when ordered, so mark sump pan locations and types on the plans. Send them with your deck takeoff for a quote.
Related Questions
Does a sump pan weaken the Type B deck?
The sump pan replaces the deck at the drain, and the cut deck around it needs support. Engineers usually detail framing or reinforcement around drain openings so the cut ribs are carried properly. Follow the opening details on the structural drawings, and do not cut large openings in the field without them.
Should I slope the steel or the insulation?
Sloping the structure keeps insulation thickness constant and is common on new framing. Tapered insulation allows level framing and is easy to adjust around drains. The architect and engineer weigh cost, roof height and energy requirements. The deck works either way.