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// CODE SNIPPET

Section 706 Existing Roofing

FBC, Existing Building 2017 > 7 Alterations—level 1 > 706 Existing Roofing
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[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).

706.1.1

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. 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. Where the existing roof covering is wood shake, slate, clay, cement or asbestos-cement tile.
  3. Where the existing roof has two or more applications of any type of roof covering.
  4. When blisters exist in any roofing, unless blisters are cut or scraped open and remaining materials secured down before applying additional roofing.
  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.

Exceptions:

  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. 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. Reserved.
  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. 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 Reinstallation 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 counterflashings 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 (HighVelocity 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 sitebuilt single-family residential structure is removed and replaced, the following procedures shall be permitted to be performed by the roofing contractor:

  1. Roof-decking attachment shall be as required by Section 706.7.1.
  2. 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.

706.7.1.1

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.

706.7.1.2

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. 0.113-inch nominal shank diameter.
  2. Ring diameter a minimum of 0.010 inch over shank diameter.
  3. 16 to 20 rings per inch.
  4. A minimum 0.280-inch full round head diameter.
  5. Ring shank to extend a minimum of 11/2 inches from the tip of the nail.
  6. Minimum 23/8 inches nail length.

TABLE 706.7.1.2

SUPPLEMENT FASTENERS AT PANEL EDGES AND INTERMEDIATE FRAMING

EXISTING FASTENERSEXISTING SPACINGVasdc 110 MPH OR LESS SUPPLEMENTAL
FASTENER SPACING SHALL BE NO
GREATER THAN
Vasdc GREATER THAN 110 MPH
SUPPLEMENTAL FASTENER SPACING
SHALL BE NO GREATER THAN
Staples or 6dAny6″ o.c.b6″ o.c.b
8d clipped head, round head,
smooth or ring shank
6″ o.c. or lessNone necessaryNone necessary
8d clipped head, round head,
smooth or ring shank
Greater than 6″ o.c.6″ o.c.a6″ o.c.a

For SI: 1 inch = 25.4 mm.

  1. Maximum spacing determined based on existing fasteners and supplemental fasteners.
  2. Maximum spacing determined based on supplemental fasteners only.
  3. Vasd shall be determined in accordance with Section 1609.3.1 of the Florida Building Code, Building or Section R301.2.1.3 of the Florida Building Code, Residential.

706.7.2 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 roof covering is removed and replaced:

  1. In High-Velocity Hurricane Zone regions:

    1. All joints in structural panel roof sheathing or decking shall be covered with a minimum 4 inch (102 mm) 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.
    2. The entire roof deck shall be covered with an approved asphalt impregnated 30# felt underlayment or approved synthetic underlayment installed with nails and tin-tabs in accordance with Section 1518.2, 1518.3 or 1518.4 of the Florida Building Code, Building. (No additional underlayment shall be required over the top of this sheet.) The synthetic underlayment shall be fastened in accordance with the manufacturer’s recommendations.
  2. Outside the High-Velocity Hurricane Zone:

    1. Underlayment shall comply with Section R905.1.1 of the Florida Building Code, Residential.

Exceptions:

  1. Roof slopes < 2:12 having a continuous roof system shall be deemed to comply with Section 706.7.2 requirements for a secondary water barrier.
  2. Clay and concrete tile roof systems installed as required by the Florida Building Code are deemed to comply with the requirements of Section 706.7.2 for Secondary Water Barriers.

706.8

When a roof covering on an existing site-built singlefamily residential structure is removed and replaced on a building that is located in the wind-borne debris region as defined in 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:

  1. Roof to wall connections shall be improved as required by Section 706.8.1.
  2. Mandated retrofits of the roof-to-wall connection shall not be required beyond a 15 percent increase in the cost of reroofing.

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

706.8.1 Roof-to-wall connections for site-built singlefamily residential structures

Where required by Section 706.8, the intersection of roof framing with the wall below shall provide sufficient resistance to meet the uplift loads specified in Table 706.8.1 either because of existing conditions or through retrofit measures. As an alternative to an engineered design, the prescriptive retrofit solutions provided in Sections 706.8.1.1 through 706.8.1.7 shall be accepted as meeting the mandated roof-to-wall retrofit requirements.

Exceptions:

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

TABLE 706.8.1

REQUIRED UPLIFT CAPACITIES FOR ROOF-TO-WALL CONNECTIONSa, b (POUNDS PER LINEAR FOOT)

ULTIMATE
DESIGN
WIND
SPEED, Vultc,d
ROOF SPAN (feet)OVERHANGS
12202428323640
Within 6 feet of
building corner
85-69.85-116.42-139.70-162.99-186.27-209.55-232.84-27
90-82.67-137.78-165.34-192.90-220.45-248.01-275.57-30.3
100-110.51-184.18-221.01-257.85-294.68-331.52-368.36-37.4
110-141.27-235.45-282.55-329.64-376.73-423.82-470.91-45.3
120-174.97-291.62-349.94-408.26-466.59-524.91-583.23-53.9
130-211.60-352.66-423.19-493.72-564.26-634.79-705.32-63.2
140-251.15-418.59-502.31-586.02-669.74-753.46-837.18-73.3
150-293.64-489.40-587.28-685.16-783.04-880.92-978.80-84.2
170-387.40-645.67-774.81-903.94-1033.08-1162.21-1291.35-108
Greater than 6
feet from building
corner
85-39.10-65.17-78.20-91.24-104.27-117.30-130.34-27
90-48.20-80.33-96.39-112.46-128.52-144.59-160.66-30.3
100-67.95-113.24-135.89-158.54-181.19-203.84-226.49-37.4
110-89.78-149.63-179.55-209.48-239.40-269.33-299.25-45.3
120-113.68-189.47-227.37-265.26-303.16-341.05-378.94-53.9
130-139.67-232.78-279.34-325.90-372.45-419.01-465.57-63.2
140-167.74-279.56-335.47-391.38-447.29-503.21-559.12-73.3
150-197.88-329.80-395.76-461.72-527.68-593.64-659.60-84.2
170-264.41-440.68-528.81-616.95-705.08-793.22-881.35-108

For SI: 1 foot = 304.8 mm; 1 pound per linear foot = 1.488 kg/m; 1 mile per hour = 0.305 m/s.

  1. The uplift loads are pounds per lineal foot of building length. For roof uplift connections multiply by 1.33 for framing spaced 16-inches on center and multiply by 2 for framing spaced 24-inches on center.
  2. The uplift loads do not account for the effects of overhangs. The magnitude of the above loads shall be increased by adding the overhang loads found in the table. The overhang loads are also based on framing spaced 12-inches on center. The overhang loads given shall be multiplied by the overhang projection and added to the roof uplift value in the table.
  3. For Ultimate design wind speeds, Vult, greater than 170 mph, wind uplift forces shall be determined in accordance with Florida Building Code, Residential, Section R301.2.1.1 of the Florida Building Code, Residential or ASCE 7.
  4. Ultimate Design Wind Speeds determined from Figure 1609.3(1) in the Florida Building Code, Building or Figure R301.2(4) in the Florida Building Code, Residential.

706.8.1.1 Access for retrofitting roof to wall connections

These provisions are not intended to limit the means for gaining access to the structural elements of the roof and wall for the purposes of retrofitting the connection. The retrofit of roof to wall connections can be made by access through the area under the eave, from above through the roof, or from the interior of the house. Methods for above access include removal of roof panels or sections thereof or removal of portions of roof paneling at selected locations large enough for access, viewing, and installing the retrofit connectors and fasteners.

Where panels or sections are removed, the removed portions shall not be reused. New paneling shall be used and fastened as in new construction.

Holes shall be deemed adequately repaired if a patch of paneling is installed with no gap greater than 1/2 inch (13 mm) between the patch and the existing sheathing and if the patch is supported using one of the following methods.

  1. Solid 11/2-inch lumber shall fully support the patch and shall be secured to the existing sheathing with #8 by 11/4-inch screws spaced a minimum of 3 inches (76 mm) around the perimeter with screws a minimum of 3/4 inch from the near edge of the hole. The patch shall be secured to the lumber with #8 × 11/4-inch screws spaced on a grid no greater than 6 inches by 6 inches (152 mm × 152 mm) with no fewer than 2 screws.
  2. Holes that extend horizontally from roof framing member to adjacent roofing framing member that are less than or equal to 7 inches (178 mm) wide along the slope of the roof shall be supported by a minimum of 2 × 4 lumber whose face is attached to each roofing framing members using a minimum of 2 each 3-inch (76 mm) long fasteners (#8 screws or 10d common nails) connecting the two. The patch shall have attached to its bottom, running horizontally, a minimum 2 × 4 either flat wise or on edge secured with #8 × 11/4-inch screws a maximum of 4 inches (102 mm) on center and no more distant from the end of the added lumber than 3 inches (76 mm). The patch shall be secured with two #8 × 11/4-inch screws to each support member.

706.8.1.2 Partially inaccessible straps

Where part of a strap is inaccessible, if the portion of the strap that is observed is fastened in compliance with these requirements, the inaccessible portion of the strap shall be presumed to comply with these requirements.

706.8.1.3 Prescriptive method for gable roofs on a wood frame wall

The anchorage of each of the exposed rafters or trusses within 6 feet (1829 mm) of the corner along the exterior wall on each side of each gable end shall be inspected. Wherever a strap is missing or an existing strap has fewer than four fasteners on each end, approved straps, ties or right angle brackets with a minimum uplift capacity of 500 pounds (740 kg) shall be installed that connect each rafter or truss to the top plate below. Adding fasteners to existing straps shall be allowed in lieu of adding a new strap provided the strap is manufactured to accommodate at least 4 fasteners at each end. Wherever access makes it possible (without damage of the wall or soffit finishes), both top plate members shall be connected to the stud below using a stud to plate connector with a minimum uplift capacity of 500 pounds (740 kg). Use of straps that connect directly from the rafter or truss to the wall stud below shall be allowed as an alternate provided the two members align with no more than 11/2 inches (38 mm) offset.

706.8.1.4 Prescriptive method for gable roofs on a masonry wall

The anchorage of each of the exposed rafters or trusses within 6 feet (1829 mm) of the corner along the exterior wall on each side of each gable end shall be inspected. Wherever a strap is missing or an existing strap has fewer than four fasteners on each end, approved straps, ties or right angle gusset brackets with a minimum uplift capacity of 500 pounds (740 kg) shall be installed that connect each rafter or truss to the top plate below or directly to the masonry wall using approved masonry screws of a length and diameter recommended by the manufacturer. In the absence of manufacturer’s recommendations, screws shall provide at least a 21/2-inch (64 mm) embedment into the concrete or masonry. When the straps or right angle gusset brackets are attached to a wood sill plate, the sill plate shall be anchored to the concrete masonry wall below. This anchorage shall be accomplished by installing 1/4- inch diameter masonry screws, each with supplementary 1/4-inch washer, having sufficient length to develop a 21/2 inch (64 mm) embedment into the concrete and masonry. These screws shall be installed within 4 inches (102 mm) of the truss or rafter on both sides of each interior rafter or truss and on the accessible wall side of the gable end truss or rafter.

706.8.1.5 Prescriptive method for hip roofs on a wood frame wall

Unless it is possible to verify through nondestructive inspection or from plans prepared by a design professional that the roof structure is anchored at least as well as outlined below, access shall be provided at a minimum to the hip rafter (commonly known as a “king jack”), to the hip girder and at each corner of the hip roof. The hip rafter (commonly known as a “king jack”), the hip girder and the rafters/trusses adjacent to the hip girder that are not anchored with a strap having at least four fasteners on each end, shall be connected to the top plate below using a strap or a right angle gusset bracket having a minimum uplift capacity of 500 pounds (740 kg). Adding fasteners to existing straps shall be allowed in lieu of adding a new strap provided the strap is manufactured to accommodate at least 4 fasteners at each end. Wherever access makes it possible (without damage of the wall or soffit finishes), both top plate members shall be connected to the stud below using a stud to plate connector with a minimum uplift capacity of 500 pounds (740 kg). Use of straps that connect directly from the hip rafter, hip girder or adjacent rafters/trusses to the wall stud below shall be allowed as an alternate provided the two members align with no more than 11/2 inch (38 mm) offset.

706.8.1.6 Prescriptive method for hip roofs on a masonry wall

Unless it is possible to verify through nondestructive inspection or from plans prepared by a design professional that the roof structure is anchored at least as well as outlined below, access shall be provided at a minimum to the hip rafter (commonly known as a “king jack”), to the hip girder and at each corner of the hip roof. The hip rafter (commonly known as a “king jack”), the hip girder and the rafters/trusses adjacent to the hip girder that are not anchored with a strap having at least four fasteners on each end, shall be connected to the concrete masonry wall below using approved straps or right angle gusset brackets with a minimum uplift capacity of 500 pounds (740 kg). Adding fasteners to existing straps shall be allowed in lieu of adding a new strap provided the strap is manufactured to accommodate at least 4 fasteners at each end. The straps or right angle gusset brackets shall be installed such that they connect each rafter or truss to the top plate below or directly to the masonry wall using approved masonry screws of a length and diameter recommended by the manufacturer. In the absence of manufacturer’s recommendations, screws shall provide at least a 21/2-inch (64 mm) embedment into the concrete or masonry. When the straps or right angle gusset brackets are attached to a wood sill plate, the sill plate shall be anchored to the concrete masonry wall below. This anchorage shall be accomplished by installing 1/4-inch (6 mm) diameter masonry screws, each with supplementary 1/4-inch (6 mm) washer, with sufficient length to develop a 21/2- inch (64 mm) embedment into the concrete and masonry. These screws shall be installed within 4 inches (102 mm) of the truss or rafter on both sides of each interior rafter or truss and on the accessible wall side of the gable end truss or rafter.

706.8.1.7 Priorities for mandated roof-to-wall retrofit expenditures

Priority shall be given to connecting the exterior corners of roofs to walls where the spans of the roofing members are greatest. For houses with both hip and gable roof ends, the priority shall be to retrofit the gable end roof-to-wall connections unless the width of the hip end is more than 1.5 times greater than the width of the gable end. When considering priorities for houses with both hip and gable roof ends, and the fifteen percent of the cost of roof replacement is sufficient to complete all of the prioritized elements pursuant to this section, but is not sufficient to complete all of the non-prioritized elements, then no portion of complete retrofit of the non-prioritized element is required.
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