Enhanced Fujita scale damage indicators and degrees of damage, chapter 18
Mid-Rise Buildings: 5-20 Storeys (MRB)
Typical Construction:
- Generally consist of rectangular shapes but can have curved or triangular footprints
- Roofs are generally flat; may have an elevator/mechanical penthouse and/or parapet walls
- Structural frame is steel or reinforced concrete
- Roofing materials are BUR or single-ply membrane with or without gravel
- Penthouse is steel framing with metal panels, or metal studs with stucco or EIFS
- Exterior cladding is glass or metal curtain walls; pre-cast concrete window wall panels or a combination of the two
- Roof structure consists of metal deck, poured gypsum deck or concrete slab
- Examples are office buildings, medical facilities, and residential buildings
| DOD | Damage Description | EXP* | LB* | UB* |
|---|---|---|---|---|
| 1 | Threshold of visible damage | 115 | 95 | 140 |
| 2 | Loss of roof covering (up to 20%) | 135 | 110 | 165 |
| 3 | Damage to penthouse roof and walls; loss of rooftop HVAC equipment | 150 | 120 | 180 |
| 4 | Damage to parapet walls or coping | 160 | 135 | 190 |
| 5 | Broken glass in curtain walls; glass in entryways; significant damage to building interior | 165 | 135 | 195 |
| 6 | Uplift of lightweight roof decking; significant loss of roofing material (more than 20%) | 190 | 160 | 225 |
| 7 | Broken curtain wall panel anchors | 210 | 175 | 240 |
| 8 | Uplift or collapse of roof structure | 220 | 190 | 255 |
| 9 | Significant damage to curtain walls and some interior walls | 235 | 195 | 270 |
| 10 | Permanent structural deformation | 340 | 290 | 430 |
*All wind speeds in km/h