www.co.worcester.md.us

Wind Resistance Requirements

The IBC and IRC designed to ensure safety to life and property from all hazards incident to building design and construction at the least possible cost consistent with national recognized standards. Being located along the Atlantic coastline, Worcester County is subject to many coastal storms, including hurricanes. This is evidenced by the County's inclusion in the 125 MPH Wind Speed Zone, exposure "C" as set forth by DHCD Codes Administration and referenced in ASCE 7-10 Minimum Design Loads for Buildings and Other Structures.

For this reason, the following basic construction design standards for all wood residential and commercial structures built in Worcester County will be strictly enforced to help reduce the risk of life and property at a minimal cost to homeowners.

  • Approved metal high wind roof rafter-to-top plate tie downs fastened in accordance with the manufacturer's instructions are required at every connection to reduce uplift.
  • Minimum fastening schedules for exterior wall and roof sheathing are 8d common nails fastened no more than four (4") inches on center on edges and no more than six (6") inches on center in the field or as specified in ICC referenced manuals.
  • Asphalt/fiberglass shingle roofing for one and two family dwellings: Shingles shall be installed as per shingle manufacturer's printed instructions for a high wind zone. Roofing for commercial structures built under the IBC: Shingles shall have a minimum of 6 fasteners per shingle section, placed in accordance with the shingle manufacturer's printed instructions.
  • Exterior wall sheathing shall either be fastened over the band joist and onto the side of the sill plate, or approved metal connectors shall be fastened as per the connector manufacturer from each wall stud to the sill plate, in required wind exposures.
  • Adequate gable end bracing, such as "K-bracing," shall be installed at all gable ends to resist wind loads, and reduce the likelihood of "racking."

The above are enforced to minimize loss of life and property during hurricanes and strong storms and are not intended to serve as the only options for minimum protection. Winds can far exceed the 120 MPH Wind Speed designated for this area creating major damage to structures which employ even the best building techniques. It is suggested that licensed design professionals be contacted for further recommendations to increase structural resistance to storms.