Specific gravity based on oven-dry weight and volume at 12% moisture content Weight, lb per ft3 At 12% moisture content At 20% moisture content Adjusting factor for each 1% change in moisture content Moisture content when green (avg), % Specific gravity based on oven-dry weight and volume when green Weight when green, lb per ft3 Softwoods: Cedar: Alaska 0.44 31.1 32.4 0.170 38 0.42 35.5 Incense 0.37 25.0 26.4 0.183 108 0.35 42.5 Port Orford 0.42 29.6 31.0 0.175 43 0.40 35.0 Western red 0.33 23.0 24.1 0.137 37 0.31 26.4 Cypress, southern 0.46 32.1 33.4 0.167 91 0.42 45.3 Douglas fir: Coast region 0.48 33.8 35.2 0.170 38 0.45 38.2 Inland region 0.44 31.4 32.5 0.137 48 0.41 36.3 Rocky Mountain 0.43 30.0 31.4 0.179 38 0.40 34.6 Fir, white 0.37 26.3 27.3 0.129 115 0.35 39.6 Hemlock: Eastern 0.40 28.6 29.8 0.150 111 0.41 43.4 Western 0.42 29.2 30.2 0.129 74 0.38 37.2 Larch, western 0.55 38.9 40.2 0.170 58 0.51 46.7 Pine: Eastern white 0.35 24.9 26.2 0.167 73 0.36 35.1 Lodgepole 0.41 28.8 29.9 0.142 65 0.38 36.3 Norway 0.44 31.0 32.1 0.142 92 0.41 42.3 Ponderosa 0.40 28.1 29.4 0.162 91 0.38 40.9 Southern shortleaf 0.51 35.2 36.5 0.154 81 0.46 45.9 Southern longleaf 0.58 41.1 42.5 0.179 63 0.54 50.2 Sugar 0.36 25.5 26.8 0.162 137 0.35 45.8 Western white 0.38 27.6 28.6 0.129 54 9.36 33.0 TABLE 10.4 Weights and Specific Gravities of Commercial Lumber Species (Continued)

Gee & Jenson West Palm Beach, Florida A hazard poses the threat that an unwanted event, possibly a catastrophe, may occur. Risk is the probability that the event will occur. Inasmuch as all buildings are subject to hazards such as hurricanes, earthquakes, flood, fire, and lightning strikes, both during and after construction, building designers and contractors have the responsibility of estimating the risks of these hazards and the magnitudes of the consequences should the events be realized. After the risk of a hazard has been assessed, the building designers and contractors, guided by building-code, design standards, zoning-code, and health-agency specifications and exercising their best judgment, should decide on an acceptable level for the risk. With this done, they should then select a cost-effective way of avoiding the hazard, if possible, or protecting against it so as to reduce the risk of the hazards occurring to within the acceptable level. Studies of building failures provide information that building designers should use to prevent similar catastrophes. Many of the lessons learned from failures have led to establishment of safety rules in building codes. These rules, however, generally are minimum requirements and apply to ordinary structures. Building designers, therefore, should use judgment in applying code requirements and should adopt more stringent design criteria where conditions dictate. Such conditions are especially likely to exist for buildings in extreme climates or in areas exposed to natural hazards, such as high winds, earthquakes, floods, landslides, and lightning. Stricter criteria should also be used for buildings that are *Revised and updated from Sec. 3, Protection Against Hazards by the late Frederick S. Merritt, Consulting Engineer. tall and narrow, are low but very large, have irregular or unusual shapes, house hazardous material or critical functions, or are of novel construction. Furthermore, building codes may not contain provisions for some hazards against which building designers nevertheless should provide protection. Examples of such hazards are vandalism, trespass, and burglary. In addition, designers should anticipate conditions that may exist in buildings in emergencies and provide refuge for occupants or safe

Too much absorption There are dead spots in the room Poor distribution Reflecting surfaces Improper shape Eliminate cause of focusing effects Echoes Alter room shape TABLE 11.35 (Continued ) Problem Possible causes Solution Sound comes right through the walls of these offices Sound leaks Eliminate leaks Sound transmission Sound isolation Vibration Vibration isolation Receiving room too quiet Masking Poor room location Proper room layout I can hear machine noises and people walking around upstairs Vibration Vibration isolation Sound transmission Sound isolation Poor room location Proper room layout Outside noises drive me crazy Poor room location Proper acoustical environment Sound leaks Eliminate leaks Sound transmission Sound isolation L. L. Beranek, Noise and Vibration Control, McGraw-Hill, Inc., New York. P. D. Close, Sound Control and Thermal Insulation of Buildings, Van Nostrand Reinhold Company, New York. M. D. Egan, Architectural Acoustics, McGraw-Hill, Inc., New York. C. M. Harris, Handbook of Acoustical Measurements and Noise Control, 3d ed., Mc- Graw-Hill, Inc., New York. P. M. Morse and K. U. Ingard, Theoretical Acoustics, McGraw-Hill, Inc., New York. L. E Yerges, Sound, Noise and Vibration Control, Van Nostrand Reinhold Company,