Florida Building Code


Enhance Your Roof: Prepare Yourself for the Latest Florida Building Code Revisions, Farewell to 30 lbs Felt and Embrace Sustainable Alternatives!

Are you fully prepared for the implementation of the recent 8th Edition of the Florida Building Code (FBC) revision introduced on December 31, 2023?

Given the recent revisions to the 2024 Florida Building Code, it’s crucial to reassess roofing materials to ensure optimal performance and sustainability. The removal of 30 lbs. felt from the code underscores concerns about its inadequate performance, especially in areas prone to high winds. The updated code now permits asphaltic self-adhered applications directly onto the wood roof deck, eliminating the necessity for mechanical fasteners that often demonstrate weak pull-through resistance in 30 lbs. felt installations. Nevertheless, many roofing contractors persist in using 30 lbs. felt out of habit, overlooking the easier installation and superior performance offered by synthetic alternatives. Given the substantial investment associated with roof replacement, it’s vital to gather all pertinent information and make informed decisions. Let’s prioritize choices that are grounded in knowledge and promote longevity and resilience for our homes and communities. Here’s a quick overview of some of the changes concerning steep-slope underlayments to kickstart your preparations.

To learn more and get assistance with your next project, reach out to our our Technical Services or Sales Representative in your area.

Tile Applications

A major code change is that Underlayment Assemblies shall be tested in accordance with FM 4474 or UL 1897. The Maximum Design Pressures (MDP) of tested assemblies will be listed in FBC Product Approvals and NOAs, similarly to low-slope Approvals.

Refer to current FBC Product Approvals (FL5259-R41) for Polyglass’ tested assemblies and associated design pressures.

HVHZ I Download | NON-HVHZ I Download

Direct To Deck

Direct to Deck Underlayments may be accepted in the HVHZ (Broward & Miami-Dade Counties) and NON-HVHZ provided the underlayment meets the designed wind uplift requirements of the project. (Check with local jurisdictions for approval.)

Polyglass’ Solution:
In Polyglass’ FBC Approvals, UDL-4 on page 6 (HVHZ) or UDL-7 on page 7 (NON-HVHZ):  TU Max or TU Plus direct to deck over min. 15/32” deck.  MDP= – 165 psf

Recover Or Mechanically Attached Anchor Sheet:

Where direct to deck application is not feasible or preferred, or where you encounter a pre-existing self-adhered on the deck that you cannot remove, an anchor sheet can be installed atop the wood decks. It is the code intent that the underlayment assembly, including the anchor sheet, is tested to meet the design wind uplift requirements. This may affect the type and/or fastening pattern of the anchor sheet that you are used to installing.

Polyglass’ Solution:

Polyanchor HV is a high performing, modified bitumen anchor sheet with excellent pull-through capabilities that has been tested to achieve superior uplift values with enhanced fastening, in conjunction with Polyglass self-adhered tile underlayments. Polyanchor HV has 2.5x greater nail pull through over 80% stronger top surface bond with Polystick Underlayments vs conventional felts.* In Polyglass’ FBC Approvals, UDL 26 on page 9 (HVHZ) or UDL-61 on page 14 (NON-HVHZ):  TU Max or TU Plus over nailed anchor sheet Polyanchor HV over min. 19/32” deck. MDP= -135 psf. The Polyanchor HV fastening rate can be enhanced by an engineer to reach up to -200 psf over 19/32” deck.

*Average based on TAS 117 (B) 95 and ASTM D1970 vs. three popular 30# felts.

Metal and Shingle Applications

For metal and shingle roof coverings, the underlayments do not need to be tested, but need to meet one of the following criteria.

1. ASTM D1970 modified bitumen self-adhered installed over the full roof deck, such as Polystick TU Plus, IR-Xe, MTS Plus or XFR. Refer to Table 2 and Table 3 in the current FBC Approvals for roof covering and substrate options.

HVHZ I Download | NON-HVHZ I Download

2. Min 3-3/4” self-adhering tape such as Elastoflex SA V Strips installed over the plywood joints, plus a layer of ASTM D226 Type II (Polyanchor HV) or similar, mechanically attached. Note that for roofs less than 4:12 pitch, two (2) layers of ASTM D226 Type II (Polyanchor HV) or similar are required.

3. Two layers of ASTM D226 Type II (Polyanchor HV) or similar installed over the full roof deck.

UL Class A Fire Ratings

In jurisdictions requiring Class A fire ratings, including but not limited to Miami-Dade and Broward Counties, roof replacement permits may require submission of UL Class A listings.

Polyglass’ Solution to achieve a Class A Fire Rating:

UL Listing R25992 “Other System” allows Polystick XFR as a single or double layer underlayment under UL Listed or Classified steel (including Galvalume), copper, stone coated shingles
and aluminum.

UL Listing R25992 “Prepared Roofing Accessories” allows Polystick IR-Xe, MTS Plus, TU Plus, XFR, or PolyAnchor HV under Class A asphalt glass fiber mat shingles.

Florida Building Code Updates

For the latest code information refer to the recent Florida Building Code updates on the ICC website.
SECTION 1504 Performance Requirements – Wind Resistance of Roofs

For more information and your next project assistance contact our Technical Services or Sales Representative in your area.