As California goes, so goes the nation? When it comes to sustainability mandates like the state’s tough Building Energy Efficiency Standards (Title 24), only time will tell.
What is certain is mandates like Title 24 and the 2021 International Energy Conservation Code (IECC), underscore the trend to greater home energy efficiency. Think how less tight homes built 20 or even 15 years ago are than today. Part of the credit goes to voluntary certification programs like Energy Star. Today the U.S. counts over 2.3 million certified Energy Star homes, with 120,000 homes certified in 2021 alone.
The good news for home builders: Energy Star certification can lift a home’s market value by up to 30%.
Key to any advance in residential energy efficiency is the envelope. California’s Title 24, for example, specifies exterior wall insulation between R-13 and R-17, depending on climate zone. In other parts of the country, local code may be based on the 2015 or 2018 IECC, like the area around Nashville, Tenn.
2x6 vs. 2x4
Michael Sr. and Michael Jr. Craddock know all about code around the Nashville area, especially the requirement for minimum R-20 envelope insulation. The father and son team own and operate M Squared Homebuilders, an infill housing specialist. The pair had two ways to meet or beat the R-20 requirement:
1. 2x6 Framing
2x6 dimensional lumber creates larger wall cavities to install more insulation, helping meet envelope code. Unfortunately, a 2x6 lumber comes with a few downsides:
- Cost and availability
- Cost of more insulation, more concrete for a wider foundation, and more finishing materials like extension jambs
- Less usable interior space (about 33.5 less square feet on a 2,400-square-foot home versus 2x4 framing)
- Heavier weight of 2x6 lumber for standing up frame sections
2. 2x4 Framing
The smaller wall cavity of 2x4 framing substantially reduces insulation volume. As a result, the Craddocks would need a way to offset 2x4 cavity limitations with a continuous insulation (CI) product.
The Craddocks researched their options. They came across a CI product, rated R-6, that “saves us about $3,000 to $3,500 per house compared to using OSB and housewrap,” explains the senior Craddock. With it, the Craddocks could avoid more expensive 2x6 construction and still meet code.
The product is OX-IS structural continuous insulation from Michigan-based OX Engineered Products, a 4-in-1 structural CI panel that offers:
- Structural sheathing
- Water-resistant barrier
- Air barrier
- Continuous insulation
OX-IS helps cut down on construction expenses. “It’s code compliant, eliminates thermal breaks, and doesn’t cost an arm and a leg,” says the senior Craddock. “The light weight of OX-IS also lets us finish framing sections on the ground and stand it right up.”
Craddock’s framing crew also likes how the panels cut easily and install with nails or staples—no special tools are required.
For the Craddocks, the search for a code-compliant envelope is over. “We found a product that costs less with better quality,” Craddock reflects.
“You can’t ask for more than that.”
Learn more about how OX-IS structural continuous insulation saves money, time and helps meet code.
