Can Cordwood Homes Pass Local Building Codes?

Designing for Compliance

Cordwood masonry construction involves building with logs or wood pieces, typically 1-2 feet long, set in a mortar mix. To meet building code requirements, cordwood homes need to be designed with a clear understanding of the local building codes, including load-bearing capacity, fire resistance, and energy efficiency. A good starting point is to research local building codes and consult with a local building official to ensure compliance. For example, the International Building Code (IBC) requires a minimum 2-hour fire-resistance rating for exterior walls. To meet this requirement, cordwood homes can be designed with a fire-resistant mortar mix and a non-combustible core, such as a 2-inch thick layer of insulation.

Building Code Requirements

Some specific building code requirements for cordwood homes include:

• Load-bearing capacity: Cordwood walls need to be designed to support the weight of the roof, floors, and any snow loads. This can be achieved by using larger logs or adding internal support structures. For example, a cordwood wall can be designed with a load-bearing capacity of 1,000 pounds per square foot.
• Insulation: Cordwood homes need to meet minimum insulation requirements to ensure energy efficiency. This can be achieved by using insulation materials, such as recycled denim or fiberglass, between the log ends. For example, a cordwood wall can be designed with an R-value of 19, which meets the minimum requirements for a Zone 6 climate.
• Mortar mix: The mortar mix used in cordwood construction needs to be fire-resistant and able to support the weight of the logs. A good starting point is to use a mix of 1 part cement, 1 part lime, and 2 parts sand. This mix has a compressive strength of 1,000 pounds per square inch, which meets the minimum requirements for a load-bearing wall.

Building a Cordwood Home

Building a cordwood home requires careful planning and attention to detail. Here are some specific techniques to consider:

• Log preparation: Logs need to be carefully prepared to ensure they fit snugly together. This can be achieved by using a log splitter or a chainsaw to remove any bark or debris.
• Mortar application: Mortar needs to be applied carefully to ensure a strong bond between the logs. This can be achieved by using a trowel to apply a thin layer of mortar to each log end.
• Insulation installation: Insulation materials need to be installed carefully to ensure proper coverage and R-value. This can be achieved by using a spray foam insulation or a blown-in insulation material.