Balance Benefits of Building Systems

Claudette Reichel  |  6/25/2008 1:39:35 AM

Here is a comparative summary of available building systems that sufficiently integrate and balance the five criteria for a sustainable, high-performance home in the Gulf Region and have particular advantages in specific conditions:

  • Fully borate pressure-treated wood frame systems (no untreated structural wood and borate-treated rigid foams) are strongly recommended in south Louisiana, Mississippi and Florida because Formosan subterranean termites are a high risk.
  • 2x4 framing with foam sheathing (without added structural sheathing) is suitable for homes that are not in a high wind zone.
  • 2x6, 24”o.c. advanced framing homes generally cost about the same as standard framed homes (depending on window area and finishing techniques) with added benefits.
    • 2x6 with foam sheathing is especially advantageous in a mixed or colder climate.
    • 2x6 framing with structural sheathing is a good option in Gulf Region hurricane zones; its stack framing can reduce strapping labor while providing sufficient insulation without added foam sheathing.
    • 2x6 lumber framing with marine grade plywood sheathing and insulated with either closed cell spray foam partially filled wall cavities or rigid foam sheathing is suitable for levee protected areas (where flooding much higher than the BFE is possible)
  • SIPS are advantageous in any climate zone and wind zones. SIPS with wood-based skins should be borate-treated and elevated well above possible flood levels. Higher material costs can be largely offset by time and labor savings for production builders. Typical costs range from comparable to 2% more than standard framing; a large amount of window area or complex roof designs erodes cost effectiveness.
  • ICF and ISPS systems are particularly advantageous in high wind, coastal, levee-protected and tornado areas, especially when used with borate-treated foam. Typical cost may be 2% to 7% more than standard framing (or comparable when reinforced for high wind zones), depending on relative costs of wood, concrete, steel and labor.
  • AAC and insulated masonry construction systems are good options in the Deep South. They may be most cost effective with a direct-applied stucco finish. AAC and insulated masonry have advantageous properties for warm, high wind and termite zones that may offset cost and experienced labor availability limitations. AAC should be elevated above possible flood levels. The other systems above offer superior insulating value for colder climate zones.
  • Steel framing systems have the advantages of termite resistance, uniformity and submergibility (suitable for levee protected areas, if treated to withstand corrosion from salt in floodwater). However, its characteristics of thermal bridging, lack of water storage buffer capacity and learning curve for residential skilled labor present challenges to those criteria. Promising research and development are under way to develop cost-effective solutions to those challenges. Insulation should be installed outside of the stud cavity to perform effectively.
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