Common Mistakes
Six Retrofit Mistakes to Avoid
The following are common mistakes we see during retrofit construction. Also, a reminder that no construction should be started until the homeowner has received EBB’s approval to begin.
#1 Incorrect Bolt/screw end distance in mudsill
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_original.webp)
#2 Nails overdriven or misplaced
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_original-1.webp)
#3 Bolts and nuts improperly installed
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_1_original-1.webp)
Bolts should be straight and all nuts should be tightened as per manufacturer specifications
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_2_original.webp)
Bolts should be flush with the top of the nut
#4 Use of non-approved angles, hold-downs, clips and foundation plates
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_3_original-e1666339078346.webp)
No work is required at the interior of the crawlspace. Hold-downs are always located at the ends of shear walls
![Earthquake Retrofit Chatsworth](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_4_original.webp)
Vertical angles have no lateral capacity and are not required by Chapter A3 or the plan sets. Note: the requirements for foundation plates include a minimum plate thickness, 2-1/2” diameter anchors and 3-1/4” diameter lag screws
#5 Cripple walls >4’-0” must be designed by an engineer or using FEMA P-1100
![Earthquake Retrofit Chatsworth](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_6_original.webp)
#6 Only Use Manufacturer Specified Concrete Anchors in Prescriptive Hardware
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_1_original-1.webp)
Bolts should be straight and all nuts should be tightened as per manufacturer specifications
![Chatsworth Earthquake Reinforcement](https://boltdownla.com/wp-content/uploads/2022/10/unnamed_2_original.webp)
Bolts should be flush with the top of the nut