Code of Massachusetts Regulations
780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
Chapter 7 - Fire and Smoke Protection Features
Section 705 - EXTERIOR WALLS
Subsection 705.8 - Openings
Current through Register 1531, September 27, 2024
Openings in exterior walls shall comply with Sections 705.8.1 through 705.8.6.
TABLE 705.8 MAXIMUM AREA OF EXTERIOR WALL OPENINGS BASED ON FIRE SEPARATION DISTANCE AND DEGREE OF OPENING PROTECTION
| FIRE SEPARATION DISTANCE (feet) | DEGREE OF OPENING PROTECTION | ALLOWABLE AREAa |
| 0 to less than 3b,c | Unprotected, Nonsprinklered (UP, NS) | Not Permitted |
| Unprotected, Sprinklered (UP, S)i | Not Permitted | |
| Protected (P) | Not Permitted | |
| 3 to less than 5d, e | Unprotected, Nonsprinklered (UP, NS) | Not Permitted |
| Unprotected, Sprinklered (UP, S)i | 15% | |
| Protected (P) | 15% | |
| 5 to less than 10e, f | Unprotected, Nonsprinklered (UP, NS) | 10%h |
| Unprotected, Sprinklered (UP, S)i | 25% | |
| Protected (P) | 25% | |
| 10 to less than 15e, f, g | Unprotected, Nonsprinklered (UP, NS) | 15%h |
| Unprotected, Sprinklered (UP, S)i | 45% | |
| Protected (P) | 45% | |
| 15 to less than 20f, g | Unprotected, Nonsprinklered (UP, NS) | 25% |
| Unprotected, Sprinklered (UP, S)i | 75% | |
| Protected (P) | 75% | |
| 20 to less than 25f, g | Unprotected, Nonsprinklered (UP, NS) | 45% |
| Unprotected, Sprinklered (UP, S)i | No Limit | |
| Protected (P) | No Limit | |
| 25 to less than 30f, g | Unprotected, Nonsprinklered (UP, NS) | 70% |
| Unprotected, Sprinklered (UP, S)i | No Limit | |
| Protected (P) | No Limit | |
| 30 or greater | Unprotected, Nonsprinklered (UP, NS) | No Limit |
| Unprotected, Sprinklered (UP, S)i | Not Required | |
| Protected (P) | Not Required |
| For SI: 1 foot = 304.8 mm. |
| UP, NS = Unprotected openings in buildings not equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1. |
| UP, S = Unprotected openings in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1. |
| P = Openings protected with an opening protective assembly in accordance with Section 705.8.2. |
| a. Values indicated are the percentage of the area of the exterior wall, per story. |
| b. For the requirements for fire walls of buildings with differing heights, see Section 706.6.1. |
| c. For openings in a fire wall for buildings on the same lot, see Section 706.8. |
| d. The maximum percentage of unprotected and protected openings shall be 25 percent for Group R-3 occupancies. |
| e. Unprotected openings shall not be permitted for openings with a fire separation distance of less than 15 feet for Group H-2 and H-3 occupancies. |
| f. The area of unprotected and protected openings shall not be limited for Group R-3 occupancies, with a fire separation distance of 5 feet or greater. |
| g. The area of openings in an open parking structure with a fire separation distance of 10 feet or greater shall not be limited. |
| h. Includes buildings accessory to Group R-3. |
| i. Not applicable to Group H-1, H-2 and H-3 occupancies. |
705.8.1 Allowable area of openings. The maximum area of unprotected and protected openings permitted in an exterior wall in any story of a building shall not exceed the percentages specified in Table 705.8.
Exceptions:
705.8.2 Protected openings. Where openings are required to be protected, fire doors and fire shutters shall comply with Section 715.4 and fire window assemblies shall comply with Section 715.5.
Exception: Opening protectives are not required where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 and the exterior openings are protected by a water curtain using automatic sprinklers approved for that use.
705.8.3 Unprotected openings. Where unprotected openings are permitted, windows and doors shall be constructed of any approved materials. Glazing shall conform to the requirements of Chapters 24 and 26.
705.8.4 Mixed openings. Where both unprotected and protected openings are located in the exterior wall in any story of a building, the total area of openings shall be determined in accordance with the following:
| (Ap/ ap) + (Au/au) <= 1 | (Equation 7-2) |
where:
Ap = Actual area of protected openings, or the equivalent area of protected openings, Ae (see Section 705.7).
ap = Allowable area of protected openings.
Au = Actual area of unprotected openings.
au = Allowable area of unprotected openings.
705.8.5 Vertical separation of openings. Openings in exterior walls in adjacent stories shall be separated vertically to protect against fire spread on the exterior of the buildings where the openings are within 5 feet (1524 mm) of each other horizontally and the opening in the lower story is not a protected opening with a fire protection rating of not less than 3/4 hour. Such openings shall be separated vertically at least 3 feet (914 mm) by spandrel girders, exterior walls or other similar assemblies that have a fire-resistance rating of at least 1 hour or by flame barriers that extend horizontally at least 30 inches (762 mm) beyond the exterior wall. Flame barriers shall also have a fire-resistance rating of at least 1 hour. The unexposed surface temperature limitations specified in ASTM E 119 or UL 263 shall not apply to the flame barriers or vertical separation unless otherwise required by the provisions of this code.
Exceptions:
705.8.6 Vertical exposure. For buildings on the same lot, opening protectives having a fire protection rating of not less than 3/4 hour shall be provided in every opening that is less than 15 feet (4572 mm) vertically above the roof of an adjacent building or structure based on assuming an imaginary line between them. The opening protectives are required where the fire separation distance between the imaginary line and the adjacent building or structure is less than 15 feet (4572 mm).
Exceptions:
