Effective April 8, 2008 revisions to Rule 9B-3.0475 the "Hurricane Mitigation Retrofits for Existing Site-Built Single Family Residential Structures" law will go into effect. The original law, in place since October of 2007, resulted in significant cost increases and permitting challenges when re-roofing a residential structure. The revised law has considerably less impact and virtually eliminates the need for a peel & stick membrane as well as additional strapping, but does still require the refastening of the deck. It also still requires installation of storm shutters on coastal homes valued in excess of $750,000 whether you want them or not.

In brief:

• Strengthening (refastening) of the roof decking attachment is still required.
  
  
• The secondary water barrier options have been expanded to include:
  • 4” wide peel & stick placed on each plywood seam throughout the entire field of the roof, (or)
  • Peel & stick placed atop the entire field of the roof, (or)
  • One layer of 30# felt atop the plywood across the entire field of the roof with a tighter fastening pattern. (No additional underlayment is required over the top of this sheet).
  
  
• The roof to wall strengthening is no longer required if:
  • The roof-to-wall connections and/or roof-to-foundation continuous load path requirements existed when the structure was built. This would mean that any structure built within the last 30 to 40 years would most likely be exempt.
  • Verification and addition of roof/truss strapping of all of the critical areas can not be performed for 15% of the reroof cost.
  
  
• The addition of debris protection (shutters) on coastal homes worth more than $750,000 is still required.

In Detail:

Below, each passage of the revised law has been quoted and underlined. Each passage is then followed by commentary intended to help the reader interpret and grasp its impact.

101 Retrofits Required. Pursuant to Section 553.844, Florida Statutes, strengthening of existing sitebuilt, single family residential structures to resist hurricanes shall be provided. Site built single- family residential structures shall mean site built single family detached residential structures.

This passage serves to identify that this law is mandatory and applies only to site-built standalone single family homes.

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

This section enables the roofing contractor to perform all of the work contemplated within this law. This passage is significant in that outside of the work contemplated by this law, a roofing contractor is not permitted to perform structural framing such as installing strapping.

(a) Roof-decking attachment and fasteners shall be strengthened and corrected as required by section 201.1.

This subsection requires that when reroofing an existing structure, the existing roof decking be re-nailed to the trusses and/or supporting framing members.

(b) A secondary water barrier shall be provided as required by section 201.2.

This subsection requires that when reroofing an existing structure, a secondary water barrier be installed atop the roof decking prior to the installation of the roofing membrane. Contrary to the original law which accepted only a “peel & stick” type system atop the plywood, the revised law permits several more conventional methods.

101.2 When a roof is replaced on a building that is located in the wind-borne debris region as defined in § 1609.2 of the Florida Building Code, Building and that has an insured value of $300,000 or more or, if the building is uninsured or for which documentation of insured value is not presented, has a just valuation for the structure for purposes of ad valorem taxation of $300,000 or more:

This section require that when reroofing an existing structure located within a wind borne debris region and having a taxable value of more than $300,000, roof/truss strapping must be verified and added as called for.

(a) Roof to wall connections shall be improved as required by section 201.3.

This subsection refers to Section 201.3 which set the requirements as to whether or not verification and addition of roof/truss strapping is required. Section 201.3 contains Exceptions which may void the necessity for supplemental roof/truss strapping.

(b) Mandated retrofits of the roof-to-wall connection shall not be required beyond a 15 percent increase in the cost of re-roofing.

This subsection caps the cost of the verification and addition of roof/truss strapping at no more than 15% of the cost of the reroof itself.

(c) Where complete retrofits of all the roof-to-wall connections as prescribed in Section 201.3 would exceed 15 percent of the cost of the re-roofing project, the priorities outlined in Section 201.3.75 shall be used to limit the scope of work to the 15 percent limit.

This subsection set the priorities of roof/truss strapping placement. When the cost of the verification and addition of roof/truss strapping exceeds 15% of the cost of the reroof itself, the priority shall be to retrofit the gable end roof-to-wall connections and the corners of roofs to walls below where the spans of the roofing members are greatest.

101.3 When any activity requiring a building permit that is applied for on or after July 1, 2008, and for which the estimated cost is $50,000 or more for a building that is located in the wind borne debris region as defined in § 1609.2 of the Florida Building Code, Building and that has an insured value of $750,000 or more, or, if the building is uninsured or for which documentation of insured value is not presented, has a just valuation for the structure for purposes of ad valorem taxation of $750,000 or more: (a) Opening protections as required within the Florida Building Code, Building or Florida Building Code, Residential for new construction shall be provided.

This subsection requires that when performing work worth more than $50,000 (that requires a permit) on an existing structure located within a wind borne debris region and having a taxable value of more than $750,000, opening protection must be added to all openings. In other words, if a permit is pulled for work that totals more then $50,000 on a beach home worth more than $750,000, that home will be required to add shutters, debris protection or replace all of its doors and windows. It is worth noting that the cost of adding shutters or replacing all of the doors and windows will eclipse the original $50,000 project.

101.4 When retrofit enhancement of gable end bracing is provided during construction which otherwise requires a permit the techniques in Appendix A shall be allowed.

This section is not a requirement but merely a recommendation that when retrofitting the gable ends on a residence, the prescribed methods be followed. Those methods have been graphically depicted and are attached in appendix A of the law.

201.2 Roof secondary water barrier for site-built single family residential structures. A secondary water barrier shall be installed using one of the following methods when reroofing.

Options (a) – (d) within this section are optional methods of achieving a secondary water barrier and Exceptions 1 & 2 can even exempt a roof.

(a) All joints in structural panel roof sheathing or decking shall be covered with a minimum 4 in. wide strip of self-adhering polymer modified bitumen tape applied directly to the sheathing or decking. The deck and self adhering polymer modified bitumen tape shall be covered with one of the underlayment systems approved for the particular roof covering to be applied to the roof.

This option calls for 4” peel & stick on each plywood seam within the field of the roof.

(b) The entire roof deck shall be covered with an approved self-adhering polymer modified bitumen sheet. No additional underlayment shall be required on top of this cap sheet for new installations.

This option calls for peel & stick atop the plywood across the entire field of the roof.

(c) The entire roof deck shall be covered with an approved asphalt impregnated 30# felt underlayment installed with nails and tin-tabs as required for the HVHZ. (No additional underlayment shall be required over the top of this sheet).

This option calls for one layer of 30# felt atop the plywood across the entire field of the roof with a tighter fastening pattern.

(d) Outside of the HVHZ, an underlayment complying with section 1507.2.3 of the Florida Building Code, Building fastened as described below or a layer of asphalt impregnated approved #30 felt shall be installed. The felt is to be fastened with 1” round plastic cap or metal cap nails, attached to a nailable deck in a grid pattern of 12 inches (305 mm) staggered between the overlaps, with 6-inch (152 mm) spacing at the overlaps. For slopes of 2:12 to 4:12 an additional layer of felt shall be installed in a shingle-fashion and lapped 19 inches and fastened as described above. (No additional underlayment shall be required over the top of this sheet).

This option calls for one layer of 30# felt atop the plywood across the entire field of the roof with a tighter fastening pattern.

Exception 1. Roof slopes < 2:12 having a continuous roof system shall be deemed to comply with section 201.2 requirements for a secondary water barrier. Exception 2. Clay and Concrete tile roof systems installed as required by the Florida Building Code are deemed to comply with the requirements of section 201.2 for Secondary Water Barriers.

201.3 Roof-to-wall connections for site-built single family residential structures. Where required by Section 101.2, the intersection of roof framing with the wall below shall be strengthened by adding metal connectors, clips, straps, and fasteners such that the performance level equals or exceeds the uplift capacities as specified in Table 201.3. As an alternative to an engineered design, the prescriptive retrofit solutions provided in Sections 201.3.31 through 201.3.64 shall be accepted as meeting the mandated roof-to-wall retrofit requirements.

This section set the requirements as to whether or not verification and addition of roof/truss strapping is required.

Exception 1. Where it can be demonstrated (by code adoption date documentation and permit issuance date) that roof-to-wall connections and/or roof-to-foundation continuous load path requirements were required at the time of original construction.

This exception basically states that if roof-to-wall connections and/or roof-to-foundation continuous load path requirements existed when the structure was built, verification and addition of roof/truss strapping is not required. This would mean that any structure built within the last 30 to 40 years would most likely not require additional roof/truss strapping.

Exception 2. Roof-to-wall connections shall not be required unless evaluation and installation of connections at gable ends or all corners can be completed for 15% of the cost of roof replacement.

This exception basically states that if verification and addition of roof/truss strapping of all of the critical areas can not be performed for 15% of the reroof cost, verification and addition of roof/truss strapping is not required.

If you have a code question, our forensic group is ready to answer your questions or assist you in developing a code compliant solution. Contact William Bracken at wbracken@brackenengineering.com.

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