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Members Need to Review Proposed Changes to Modular Building Code

The South Carolina Building Code Council (SCBCC) is in the process of modifying and adopting the new building code proposed for modular homes in the state. SCMHI needs to hear about any problems or concerns before the code goes into effect so that we can lobby to get them removed.

We recommend that all member manufacturers purchase a copy of this booklet and have their engineers review the changes. Click here for a purchase link to the booklet overviewing changes in the 2021 IRC.

Additionally, below are a list of notable changes found by SCMHI staff and members to date.

If you have a comment or concern, please reach out to us. The association is here to advocate on your behalf. Contact Mark Dillard, Exectuive Director at  (803) 771-7823 ext.4 or

Notable Changes in 2021 IRC

  • Braced wall lines must be placed on a physical wall or placed between multiple walls.
  • The rated separation for two-family dwellings is 1 hour whether or not a lot line exists between units.
  • Emergency escape and rescue openings require a clear 36-inch-wide path to a public way.
  • An engineered design is required for storm shelters.
  • A habitable attic is limited to one-half the area of the story below and the dwelling requires sprinklers.
  • Updated Wind Speed maps match IBC and ASCE 7 maps.
  • Deck design now considers snow load, tributary area for footing and post height, and guard details.
  • Specific requirements for deck guardrails were added.
  • Component and cladding wind pressures in Table R301.2(2) are updated for new design wind speeds and hip or gable roof profiles.
  • Minimum footing size tables are revised to more accurately reflect current practice.
  • Cripple wall requirements apply only to exterior cripple walls.
  • New appendices for cob construction and 3D printed construction are added.
  • A 30 percent reduction of airflow is permitted for balanced ventilation systems.
  • Commercial gas cooking appliances are prohibited.
  • The head pressure for a water test of DWV systems increased to 10 feet.
  • Air vacuum testing is now permitted for plastic piping DWV systems.
  • Section P2904 for dwelling sprinklers is expanded to more closely align with NFPA 13D.
  • An emergency service disconnect is required in a readily accessible outdoor location.
  • A surge-protective device (SPD) is now required at the service panel.
  • The number of receptacle outlets required for peninsular and island countertops in kitchens is determined by the area of the countertop surface.
  • GFCI protection is now required for damp and wet locations not included in the other 10 areas requiring GFCI protection.