2017 Florida Building Code 706.1.1 25% Rule

2017 Florida Building Code – Existing Building, Sixth Edition

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If you do not have 25% of your asphalt shingled roof damaged you should look at the repairability of the roof in order to get coverage for a new roof. There is a test called a Brittle test that can help you determine if the roof can be repaired.


[BS] 706.1 General.

Materials and methods of application used for recovering or replacing an existing roof covering shall comply with the requirements of Chapter 15 of the Florida Building Code, Building, or Chapter 9 of the Florida Building Code, Residential. Roof repairs to existing roofs and roof coverings shall comply with the provisions of this code.

Exception: Reroofing shall not be required to meet the minimum design slope requirement of one-quarter unit vertical in 12 units horizontal (2-percent slope) in Section 1507 of the Florida Building Code, Building for roofs that provide positive roof drainage (High-Velocity Hurricane Zones shall comply with Sections 1515.2.2.1 and 1516.2.4 of the Florida Building Code, Building).


Not more than 25 percent of the total roof area or roof section of any existing building or structure shall be repaired, replaced or recovered in any 12-month period unless the entire existing roofing system or roof section is replaced to conform to requirements of this code.

[BS] 706.2 Structural and construction loads.

Structural roof components shall be capable of supporting the roof-covering system and the material and equipment loads that will be encountered during installation of the system.

[BS] 706.3 Recovering versus replacement.

New roof coverings shall not be installed without first removing all existing layers of roof coverings down to the roof deck where any of the following conditions occur:

  1. 1.Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.

  2. 2.Where the existing roof covering is wood shake, slate, clay, cement or asbestos-cement tile.

  3. 3.Where the existing roof has two or more applications of any type of roof covering.

  4. 4.When blisters exist in any roofing, unless blisters are cut or scraped open and remaining materials secured down before applying additional roofing.

  5. 5.Where the existing roof is to be used for attachment for a new roof system and compliance with the securement provisions of Section 1504.1 of the Florida Building Code, Building cannot be met.


  1. 1.Building and structures located within the High-Velocity Hurricane Zone shall comply with the provisions of Sections 1512 through 1525 of the Florida Building Code, Building.

  2. 2. Complete and separate roofing systems, such as standing-seam metal roof systems, that are designed to transmit the roof loads directly to the building’s structural system and that do not rely on existing roofs and roof coverings for support, shall not require the removal of existing roof coverings.

  3. 3.Reserved.

  4. 4.The application of a new protective coating over an existing spray polyurethane foam roofing system shall be permitted without tear-off of existing roof coverings.

  5. 5.Roof Coating. Application of elastomeric and or maintenance coating systems over existing asphalt shingles shall be in accordance with the shingle manufacturer’s approved installation instructions.

[BS] 706.4 Roof recovering.

Where the application of a new roof covering over wood shingle or shake roofs creates a combustible concealed space, the entire existing surface shall be covered with gypsum board, mineral fiber, glass fiber or other approved materials securely fastened in place.

[BS] 706.5 Re-installation of materials.

Existing slate, clay or cement tile shall be permitted for reinstallation, except that damaged, cracked or broken slate or tile shall not be reinstalled. Existing vent flashing, metal edgings, drain outlets, collars and metal counter flashing shall not be reinstalled where rusted, damaged or deteriorated. Aggregate surfacing materials shall not be reinstalled (High-Velocity Hurricane Zones shall comply with Sections 1512 through 1525 of the Florida Building Code, Building).

[BS] 706.6 Flashings.

Flashings shall be reconstructed in accordance with approved manufacturer’s installation instructions. Metal flashing to which bituminous materials are to be adhered shall be primed prior to installation (High Velocity Hurricane Zones shall comply with Sections 1512 through 1525 of the Florida Building Code, Building).

706.7 Mitigation.

When a roof covering on an existing site built single-family residential structure is removed and replaced, the following procedures shall be permitted to be performed by the roofing contractor:

  1. (a)Roof-decking attachment shall be as required by Section 706.7.1.

  2. (b)A secondary water barrier shall be provided as required by Section 706.7.2.

Exception: Single-family residential structures permitted subject to the Florida Building Code are not required to comply with this section.

706.7.1 Roof decking attachment for site-built singlefamily residential structures.

For site-built single-family residential structures the fastening shall be in accordance with Section 706.7.1.1 or 706.7.1.2 as appropriate for the existing construction. 8d nails shall be a minimum of 0.113 inch (2.9 mm) in diameter and shall be a minimum of 21/4 inches (57 mm) long to qualify for the provisions of this section for existing nails regardless of head shape or head diameter.


Roof decking consisting of sawn lumber or wood planks up to 12 inches wide and secured with at least two nails (minimum size 8d) to each roof framing member it crosses shall be deemed to be sufficiently connected. Sawn lumber or wood plank decking secured with smaller fasteners than 8d nails or with fewer than two nails (minimum size 8d) to each framing member it crosses shall be deemed sufficiently connected if fasteners are added such that two clipped head, round head, or ring shank nails (minimum size 8d) are in place on each framing member it crosses.


For roof decking consisting of wood structural panels, fasteners and spacing required in columns 3 and 4 of Table 706.7.1.2 are deemed to comply with the requirements of Section 707.3, Florida Building Code, Existing Building for the indicated design wind speed range. Wood structural panel connections retrofitted with a two part urethane based closed cell adhesive sprayed onto the joint between the sheathing and framing members are deemed to comply with the requirements of Section 707.3, Florida Building Code, Existing Building, provided testing using the manufacturer’s recommended application on panels connected with 6d smooth shank nails at no more than a 6-inch edge and 12-inch field spacing demonstrate an uplift resistance of a minimum of 200 psf.

Supplemental fasteners as required by Table 706.7.1.2 shall be ASTM F1667 classification RSRS-01 ring shank nails with the following minimum dimensions:

  1. 1.0.113-inch nominal shank diameter.

  2. 2.Ring diameter a minimum of 0.010 inch over shank diameter.

  3. 3.16 to 20 rings per inch.

  4. 4.A minimum 0.280-inch full round head diameter.

  5. 5.Ring shank to extend a minimum of 11/2 inches from the tip of the nail

  6. 6.Minimum 23/8 inches nail length.

  7. https://codes.iccsafe.org/public/document/FEBC2017/chapter-7-alterations-level-1

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