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

Table 18. Degree of Damage (DOD) for Expected (EXP), Lower Bound (LB) and Upper Bound (UB)
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