Enhanced Fujita scale damage indicators and degrees of damage, chapter 17

Low-Rise Buildings: 1-4 Storeys (LRB)

Typical Construction:

Generally consist of rectangular modules but can be “odd shaped” in plan-view sense
Most will have flat roofs but can have gable, hip or mansard shapes
Roofing materials include BUR, single-ply membrane, metal panels or standing seam
Roof deck is wood or metal deck, poured gypsum deck or concrete slab
Steel or reinforced concrete structural frame
Glass and metal curtain walls, metal studs with EIFS, non-bearing masonry walls with stucco or brick veneer
Examples are office buildings, medical facilities, and bank buildings

Notes:

With hip roof, increase toward upper-bound wind speed for Degree of Damage 3 (DODx) and DOD5

Table 17. 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	110	90	135
2	Loss of roof covering (up to 20%)	130	110	165
3	Uplift of metal roof decking at eaves and roof corners: significant loss of roofing material (more than 20%)	165	135	195
4	Broken glass in windows, entryways or atriums	165	135	195
5	Uplift of lightweight roof structure	215	185	255
6	Significant damage to exterior walls and some interior walls	230	195	270
7	Complete destruction of all or a large section of building	305	260	355

*All wind speeds in km/h