Where required by Section R907.8, the intersection of roof framing with the wall below shall provide sufficient resistance to meet the uplift loads specified in Table R907.8.1 either because of existing conditions or through retrofit measures. As an alternative to an engineered design, the prescriptive retrofit solutions provided in Sections R907.8.1.1 through R907.8.1.7 shall be accepted as meeting the mandated roof-to-wall retrofit requirements.
- 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.
- 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.
REQUIRED UPLIFT CAPACITIES FOR ROOF-TO-WALL CONNECTIONSa, b (POUNDS PER LINEAR FOOT)
|Ultimate Design Wind Speed, Vult||Roof Span (feet)||Overhangs|
|Within 6 feet of building corner||85||-69.85||-116.42||-139.70||-162.99||-186.27||-209.55||-232.84||-27|
|Greater than 6 feet from building corner||85||-39.10||-65.17||-78.20||-91.24||-104.27||-117.30||-130.34||-27|
- 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.
- 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.
- For Ultimate Design Wind Speeds, Vult, greater than 170 mph, wind uplift forces shall be determined in accordance with Section R802.3 or ASCE 7.
- Ultimate Design Wind Speeds determined from Figure R301.2(4).
- 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 (19 mm) from the near edge of the hole. The patch shall be secured to the lumber with #8 × 1-1/ 4 inch screws spaced on a grid no greater than 6 inches by 6 inches (152 mm by 152 mm) with no fewer than two screws.
- 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 minimum of 2 × 4 lumber whose face is attached to each roofing framing members using a minimum of two 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 × 1-11/4 inch screws to each support member.