Which Insulation Systems Work Best Over Type B Deck in Florida?
No insulation product is Florida compliant on its own; the whole roof assembly is. Over 1.5" Type B deck, the common choices are rigid board insulation fastened or adhered to the deck, and cementitious insulating fill on vented Type B. Pick an assembly with the Florida approval and wind uplift rating your project needs. We supply the deck that assembly specifies.
Common assemblies over Type B
- Rigid board insulation, often with a cover board, mechanically fastened through to the deck or adhered, under a single-ply or built-up membrane.
- Lightweight cementitious insulating fill over vented Type B, with the membrane attached to the fill.
- Multiple board layers with staggered joints when the energy code calls for higher thermal resistance.
What makes the assembly compliant
The Florida Building Code checks three things: thermal performance under the energy code, fire classification of the roof covering, and wind uplift resistance of the tested assembly. In the High-Velocity Hurricane Zone (Miami-Dade and Broward), roof components need product approval for that zone. The approval lists the deck it was tested on, often by gauge and fastening, so match the deck to it.
Where the deck matters
Insulation fasteners pull out of the deck, so the gauge affects uplift capacity. The flat top flanges of the 6" rib spacing give the boards bearing. Tell us the roof assembly and we will quote the gauge and finish it calls for, and send the documentation your permit requires.
Related Questions
Does deck gauge affect insulation fastener pullout?
Yes. Screws for mechanically attached insulation and membranes rely on the deck for pullout resistance, and heavier gauges generally hold better. Roof assembly approvals often name a minimum deck gauge for that reason. Check the approval for your roof system and specify at least that gauge; we supply 22, 20, 18 and 16 gauge Type B.
Can I use lightweight insulating concrete on standard Type B?
Insulating fill is normally placed on vented deck so the water in the mix can escape. The catalog offers 1.5" Type B in a vented version for this purpose. Follow the fill manufacturer's requirements and the approved assembly; if it calls for vented deck, order it that way from the start.