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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 CRMP's approval to begin.

Common Construction Mistakes

#1 Incorrect Bolt/screw end distance in mudsill
Retrofit Mistakes to Avoid: Incorrect Bolt/screw end distance in mudsill - anchor bolt
Retrofit Mistakes to Avoid: Incorrect Bolt/screw end distance in mudsill - foundation plate

#2 Nails overdriven or misplaced
Retrofit Mistakes to Avoid: Nails overdriven or misplaced - correct edge nail
Retrofit Mistakes to Avoid: Nails overdriven or misplaced - nails on a seam

Nails on Seam

#3 Bolts and nuts improperly installed
Retrofit Mistakes to Avoid: Bolts and nuts improperly installed - improper installed nuts
Retrofit Mistakes to Avoid: Bolts and nuts improperly installed - improper installed nuts image 2
  • Bolts should be straight and all nuts should be tightened as per manufacturer specifications.
  • Bolts should be flush with the top of the nut.

#4 Use of non-approved angles, hold-downs, clips and foundation plates
Retrofit Mistakes to Avoid: Use of non-approved angles, hold-downs, clips and foundation plates - non-approved hold downs
  • No work is required at the interior of the crawlspace. Hold-downs are always located at the ends of shear walls.
  • 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.
Retrofit Mistakes to Avoid: Use of non-approved angles, hold-downs, clips and foundation plates - non-approved hold angles

#5 Cripple walls >4’-0” must be designed by an engineer or using FEMA P-1100
Retrofit Mistakes to Avoid: Cripple walls >4’-0” must be designed by an engineer or using FEMA P-1100
  • Walls greater than 4’-0” require special attention as they may require hold-downs at each end.
  • Chapter A3, Plan Set A and the LA Standard Plan Set all require an engineered design for walls greater than 4’.
  • Check with the building department to see if they allow use of FEMA P-1100.

#6 Only Use Manufacturer Specified Concrete Anchors in Prescriptive Hardware
Retrofit Mistakes to Avoid: Only Use Manufacturer Specified Concrete Anchors in Prescriptive Hardware - Mitek SRC Requires PowerStud® anchors


Mitek SRC Requires PowerStud® anchors
  • Prescriptive hardware such as the SRC or URFP must be installed per the manufacturer’s requirements unless a registered design professional specifies the anchor.
  • Check the manufacturer’s requirements for approved concrete/masonry anchors.

(Note: LA Standard Plan Set #1 requires all anchors have current LARR approval.)
Retrofit Mistakes to Avoid: Only Use Manufacturer Specified Concrete Anchors in Prescriptive Hardware - Mitek SRC Requires PowerStud® anchors - Simpson Strong-tie URFP requires SET-3G, AT-XP, or Titen HD


Simpson Strong-tie URFP requires SET-3G, AT-XP, or Titen HD