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Home My WebLink AboutCity LR HDC Letter Report 9-10-18(§ h. james engstrom & associates, inc, / engineers September 10, 2018 Chair Ted Holder Historic District Commission 723 West Markham Little Rock, AR 72201 Dear Sir, Our firm, H. James Engstrom & Associates, Inc. was employed by the City of Little Rock in 2016 to have me give consultation and advice on certain technical engineering issues related to Mr_ William Page Wilson's application to the Little Rock Historic District for construction of his building at 1001 McMath Avenue in the historic district and possible legal proceedings between all parties concerned. In this regard I was given numerous documents to study and review such as, but not limited to, transcripts and minutes of the Historic District Commission meetings, the building drawings, and technical reports. This letter is a brief summary of my findings related to one of these technical issues regarding the Hardie board siding's ability to resist/sustain wind loads. Mr. Wilson contended that the Hardie board siding he originally intended to use and actually installed on two sides of the building was not strong enough to meet the requirements of the current Arkansas Building Code. He contended the building code which had been revised in 2012 had increased the required wind velocity the building must resist from 85 miles per hour to 115 miles per hour and that the Hardie siding could only achieve a maximum design wind velocity of 85 mile per hour and for this reason he could not use this siding. 1 100 west 2nd street / little rock, arkansas 72201 / 501/376-7246 / fax/501/376-6627 He is wrong. The person(s) making these statements do not appear to have the technical expertise (in the structural engineering field) to understand and properly determine the wind requirements of the current state building code and the wind capacity of the Hardie siding. The two wind speeds to which he refers are not meant to be used by the structural engineers in the same manner of design. The current building code allows the engineer to design the building by choosing one of two different design procedures. When the designer uses the procedure referred to as Allowable Stress Design (ASD), he only has to determine the structural element can resist a lower wind velocity referred to as V,asd. When the designer uses the other procedure referred to as Ultimate Stress Design (ULT), he has to determine that the structural element can resist a higher wind speed normally referred to as V,ult. Mr. Wilson's contention that the new state building code increased the required wind speed from what the older code required is wrong. The lower wind speed he contends was in the older code is the V,asd and the higher speed he refers to in the new code is the different type wind speed, V,ult. The current building code would require this building be able to sustain an Ultimate Design Wind Speed, V,ult of 115 miles per hour and/or a Basic Design Wind Speed, V,asd (Allowable Stress Design) of 89 miles per hour. If Mr. Wilson used the HardiePlank, 5/16" thick, 8.25" width that the documents given to me indicate he used and he properly connected it to 2x4 wood studs at 16 inches on center as indicated, it should be more than strong enough to resist the current state building code requirements according to the ICC -ES Report, ESR -2290 which is accepted by the current building code. This Report evaluates this type of Hardie siding and includes tables giving the results of their testing that provides wind speeds that the siding can safely sustain_ Using this Report, I analyzed the building regarding wind velocities it should be designed to withstand and what velocity the HardiePlank siding would be capable of sustaining. Table 4 (pages 9 and 10; attached herewith) of the Report give the maximum wind speeds (both V,asd and V,ult) that 5116 " thick by 8.25" width HardiePlank can sustain for various methods of connecting it to the building. If this HardiePlank were connected to the building by nailing it with 6d nails faced nailed to 2x4 wood at 16" on center spacing ( as indicated in the documents), it would safely sustain a Basic Wind Speed, V,asd (Allowable Stress Design) of 139 miles per hour and an Ultimate Design Wind Speed, V,ult (Ultimate Stress Design) of 179 miles per hour. If the same siding and connections were used, but the nail size were increased to 8d nails, it would sustain a Basic Wind Speed, V,asd of 170 miles per hour and an Ultimate Design Wind Speed, V,ult of 219 miles per hour. This HardiePlank siding, if properly installed, is able to resist/sustain much higher wind speeds than required by both the earlier and the current state building codes. Respectfully Submitted, H. James Engstrom, PE, President H. James Engstrom & Associates, Inc. pZOF. Es5IGNAL N0. 3 125 �,10 () FSAy a sa •+s ♦• QH. JAMES io i ENGSTROM a CG ASSOC., INC. --4 C Y v No. 164 a aaaa'••�QL1, ''�'�7��r ��+a+rrsaNs ESR- 22901 Most Widely Accepted and Trusted Page 9 of 25 TABLE 4 ---MAXIMUM BASIC WIND SPEED (rnphi f (Continued) 2012 IRC, 2009 2012 IBC IBCdRC, 2006 IBC1IRC (Ultimate Design (Basic Wind Speed, AW&nd Speed, PRODUCT PRODUCT DIMENSION 1N.) FASTENER Type FASTENING METHOD2 FRAME TYPE' - s STUD SPACING (IN.) BUILDING HEIGHT (FT.) EXPOSURE EXPOSURE CATEGORY CATEGORY THICK, WIDTH 8 C D 8 C D HardiePtanks s 116 7.25 6d common Face [flailed Through plank overlap 2X4 .wood 16 0-15 156 142 129 202 183 166 20 156 138 126 202 178 162 40 150 128 118 193 165 153 60 142 123 114 183 159 147 HardiePlank 6118 7.5 6d common Face Nailed Through plankoverlop wood WO°d 16 0-15 153 139 126 197 179 163 20 15$ 135 123 197 174 159 40 147 125 116 190 162 150 60 139 120 112 179 155 144 HardiePlank° _._ 5116 8 6d common Face Nailed Through plank overlap 2X4 wood 16 0-15 147 134 121 190 172 157 20 147 130 118 190 168 153 40 141 121 111 182 156 144 .60 . 134. _ - .116..- 108.-, 172 150 139 HardiePlank° 51,5 8.25 6d common Face Nailed Through plank overlap 2X4 wood 16 0-15 145 131 119 187 169 154 20 145 127 116 187 165 150 40 139 119 110 179 ' 153 141 60 131 114 106 'f69 147 136 HardiePlank' 5176 9.25 6d common Face Nailed Through plank overlap wood 16 0=15 _ .. ...135-.. f23 .--111 ._....,F75 158- ..144 20 135 119 109 175 154 141 40 130 111 102 168 143 132 60 123 106 99 158 137 128 HardiePFank° 51,6 9.5 6d common Face Nailed Through plank overlap ow od 16 0-15 133 121 110 172 156 142 20 133 117 107 172 152 138 40 128 109 101 165 141 130 60 121 105 97 156 135 126 Hard€eP€ankP 5116 5.25 6d common Face Nailed Through plank overlap 2x4 wood 24 0-15 156 142 129 201 183 166 20 156 138 126 201 178 162 40 150 128 118 193 165 153 60 142 123 114 183 159 147 HardiePlank3 5116 6.25 6d common Face Nailed Through plank overlap 2X4 wood 24 0-15 140 127 115 180 164 149 20 140 123 112 180 159 145 40 134 115 106 173 148 137 6o 1.27 110 102 164 142 132 HardiePlank° 5116 7.25 6d common Face Nailed Through plank overlap v ood 24 0-15 127 116 105 165 149 138 20 127 112 103 165 145 132 40 122 105 97 158 135 125 60 116 100 93 149 130 120 HardiePlank° 5rss 7.5 6d common Face Nailed Through plank overlap wood 24 0-15 125 113 103 161 146 133 20 125 110 100 161 142 130 40 120 102 95 155 132 122 60 113 96 91 146 127 118 ESR- 22901 Most Widely Accepted and Trusted Page 10 of 25 TABLE 4—MAXIMUM BASIC WIND SPEED (mphf (Continued) 2012 IRC, 2009 JBC/IRC, 2005 iBCnRC (Basic Wind speed, V,u,3 'I ) 20121BC (Uwmlate Design Wind speed, V it ' ) PRODUCT PRODUCT DIMENSION IN. FASTENER TYPE FASTENING METHOD; FRAME TYPE" gip SPACING (IN.) BUILDING HEIGHT (FT.) B EXPOSURE CATEGORY C R EXPOSURE CATEGORY B TC D WIDTH HardiePlank° 51rs 8 6d common Face NaiM Through plank overlap 2X4 wood 24 0-15 120 109 99 155 141 128 20 120 106 97 155 1 125 40 115 99 91 149 127 117 80 109 95 88 141 122 113 HardiePlank° 511 fi 8.25 6d common Face Nailed Through plank overlap 2%4 wood 24 0-15 118 107 97 152 138 126 20 118 104 95 152 134 123 40 113 97 89 146 125 115 60 107 93 86 138 120 111 HardiePlank� 51E6 9.25 6d common Fare Nailed Through plank overlap wow 24 0-15 110 100 91 142 129 117 20 110 97 89 142 126 115 40 106 91 - 137 117 - 60 100 87 - 129 112 - HardiePlanlO 5116 9.5 6d common Face.Naiied Through plank overlap 2X4 vmod 24 0-15 109 99 90 140 127 116 20 109 95 87 140 124 113 40 104 89 - 135 115 - 60 99 85 - 127 110 - hlardiePlank® 511s 5.25 8d common Face Nailed Through plank overlap } ood 16 0-15 170 170 170 219 219 219 20 170 170 170 219 219 219 40 170 170 170 219 213 219 60 170 170 170 219 219 219 HardiePlane 51Es 6.25 ed common Face Nailed Through plank overlap X4 v 16 0-15 170 170 170 219 219 219 20 170 170 170 219 219 219 40 170 170 161 219 219 208 60 170 168 156 219 217 201 HardiePlane -5116 7.25 ad common Face Nailed Through plank overlap 2X4 2X4 wow40 16 0-15 170 170 160 219 219 207 219 219 20 170 170F147 203 170 160219 207 190 60 170 153 142 219 198 183 HardiePlane 5/to 7.5 8d common Face Nailed Through plank overlap 2X4 iNood 16 0-15 170 170 157 219 219 203 20 170 168 154 219 217 199 40 170 157 145 219 203 187 60 170 150 139 219 194 179 HardiePlank° 511a 8 ad common Face Nailed Through plank overlap 2X4 N°Od 16 0-15 170 167 151 219 216 195 20 170 162 148 219 209 191 40 170 151 139 219 195 179 60 167 144 134 216 166 173 HardiePlank� Sits 8.25 ad common Face Nailed Through plank overlap wood 16 0-15 170 164 149 218 212 .192 20 170 159 145 219 205 " 187 } 40 ti 170 f 148 1 137 2 191 177 60 164 142 132 212 183 170