Code of Massachusetts Regulations
780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
Chapter 15 - Roof Assemblies and Rooftop Structures
Section 1507 - REQUIREMENTS FOR ROOF COVERINGS
Subsection 1507.8 - Wood shingles
Current through Register 1531, September 27, 2024
The installation of wood shingles shall comply with the provisions of this section and Table 1507.8.
TABLE 1507.8 WOOD SHINGLE AND SHAKE INSTALLATION
| ROOF ITEM | WOOD SHINGLES | WOOD SHAKES | |
| 1. Roof slope | Wood shingles shall be installed on slopes of three units vertical in 12 units horizontal (3:12) or greater. | Wood shakes shall be installed on slopes of four units vertical in 12 units horizontal (4:12) or greater. | |
| 2. Deck requirement | |||
| Temperate climate | Shingles shall be applied to roofs with solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be less than 1' *4'nominal dimensions and shall be spaced on center equal to the weather exposure to coincide with the placement of fasteners. | Shakes shall be applied to roofs with solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be less than 1' *4'nominal dimensions and shall be spaced on center equal to the weather exposure to coincide with the placement of fasteners. When 1' *4'spaced sheathing is installed at 10 inches, boards must be installed between the sheathing boards. | |
| In areas where the average daily temperature in January is 25°F or less or where there is a possibility of ice forming along the eaves causing a backup of water. | Solid sheathing required. | Solid sheathing is required. | |
| 3. Interlayment | No requirements. | Interlayment shall comply with ASTM D 226, Type 1. | |
| 4. Underlayment | |||
| Temperate climate | Underlayment shall comply with ASTM D 226, Type 1. |
Underlayment shall comply with ASTM D 226, Type 1. |
|
| In areas where there is a possibility of ice forming along the eaves causing a backup of water. | An ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall extend from the eave's edge to a point at least 24 inches inside the exterior wall line of the building. | An ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall extend from the lowest edges of all roof surfaces to a point at least 24 inches inside the exterior wall line of the building. | |
| 5. Application | |||
| Attachment | Fasteners for wood shingles shall be hot- dipped galvanized or Type 304 (Type 316 for coastal areas) stainless steel with a minimum penetration of 0.75 inch into the sheathing. For sheathing less than 0.5 inch thick, the fasteners shall extend through the sheathing. | Fasteners for wood shakes shall be hot-dipped galvanized or Type 304 (Type 316 for coastal areas) with a minimum penetration of 0.75 inch into the sheathing. For sheathing less than 0.5 inch thick, the fasteners shall extend through the sheathing. | |
| No. of fasteners | Two per shingle. | Two per shake. | |
| Exposure | Weather exposures shall not exceed those set forth in Table 1507.8.7. | Weather exposures shall not exceed those set forth in Table 1507.9.8. | |
| Method | Shingles shall be laid with a side lap of not less than 1.5 inches between joints in courses, and no two joints in any three adjacent courses shall be in direct alignment. Spacing between shingles shall be 0.25 to 0.375 inch. | Shakes shall be laid with a side lap of not less than 1.5 inches between joints in adjacent courses. Spacing between shakes shall not be less than 0.375 inch or more than 0.625 inch for shakes and taper sawn shakes of naturally durable wood and shall be 0.25 to 0.375 inch for preservative-treated taper sawn shakes. | |
| Flashing | In accordance with Section 1507.8.8. | In accordance with Section 1507.9.9. | |
| For SI: 1 inch = 25.4 mm, °C = [(°F) - 32]/1.8. |
1507.8.1 Deck requirements. Wood shingles shall be installed on solid or spaced sheathing. Where spaced sheathing is used, sheathing boards shall not be less than 1-inch by 4-inch (25 mm by 102 mm) nominal dimensions and shall be spaced on centers equal to the weather exposure to coincide with the placement of fasteners.
1507.8.2 Deck slope. Wood shingles shall be installed on slopes of three units vertical in 12 units horizontal (25-percent slope) or greater.
1507.8.3 Underlayment. Underlayment shall comply with ASTM D 226, Type I or ASTM D 4869.
1507.8.4 Ice barrier. In areas where there has been a history of ice forming along the eaves causing a backup of water, an ice barrier that consists of at least two layers of underlayment cemented together or of a self-adhering polymer-modified bitumen sheet shall be used in lieu of normal underlayment and extend from the lowest edges of all roof surfaces to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
Exception: Detached accessory structures that contain no conditioned floor area.
1507.8.5 Material standards. Wood shingles shall be of naturally durable wood and comply with the requirements of Table 1507.8.5.
TABLE 1507.8.5 WOOD SHINGLE MATERIAL REQUIREMENTS
| MATERIAL | APPLICABLE MINIMUM GRADES | GRADING RULES |
| Wood shingles of naturally durable wood | 1, 2 or 3 | CSSB |
| CSSB = Cedar Shake and Shingle Bureau |
1507.8.6 Attachment. Fasteners for wood shingles shall be corrosion resistant with a minimum penetration of 3/4 inch (19.1 mm) into the sheathing. For sheathing less than 1/2 inch (12.7 mm) in thickness, the fasteners shall extend through the sheathing. Each shingle shall be attached with a minimum of two fasteners.
1507.8.7 Application. Wood shingles shall be laid with a side lap not less than 11/2 inches (38 mm) between joints in adjacent courses, and not be in direct alignment in alternate courses. Spacing between shingles shall be 1/4 to 3/8 inches (6.4 to 9.5 mm). Weather exposure for wood shingles shall not exceed that set in Table 1507.8.7.
TABLE 1507.8.7 WOOD SHINGLE WEATHER EXPOSURE AND ROOF SLOPE
| ROOFING MATERIAL |
LENGTH
(inches) |
GRADE | EXPOSURE (inches) | |
| 3:12 pitch to < 4:12 | 4:12 pitch or steeper | |||
| Shingles of naturally durable wood | 16 | No. 1 No. 2 No. 3 | 3.75 3.5 3 | 5 4 3.5 |
| 18 | No. 1 No. 2 No. 3 | 4.25 4 3.5 | 5.5 4.5 4 | |
| 24 | No. 1 No. 2 No. 3 | 5.75 5.5 5 | 7.5 6.5 5.5 | |
| For SI: 1 inch = 25.4 mm. |
1507.8.8 Flashing. At the juncture of the roof and vertical surfaces, flashing and counterflashing shall be provided in accordance with the manufacturer's installation instructions, and where of metal, shall not be less than 0.019-inch (0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant metal. The valley flashing shall extend at least 11 inches (279 mm) from the centerline each way and have a splash diverter rib not less than 1 inch (25 mm) high at the flow line formed as part of the flashing. Sections of flashing shall have an end lap of not less than 4 inches (102 mm). For roof slopes of three units vertical in 12 units horizontal (25-percent slope) and over, the valley flashing shall have a 36-inch-wide (914 mm) underlayment of either one layer of Type I underlayment running the full length of the valley or a self-adhering polymer-modified bitumen sheet complying with ASTM D 1970, in addition to other required underlayment. In areas where the average daily temperature in January is 25°F (-4°C) or less or where there is a possibility of ice forming along the eaves causing a backup of water, the metal valley flashing underlayment shall be solidly cemented to the roofing underlayment for slopes under seven units vertical in 12 units horizontal (58-percent slope) or self-adhering polymer-modified bitumen sheet shall be installed.
