High Performance Attics (HPAs) are currently specified for almost every new home in climate zones 11-13 because they achieve the highest compliance gains per dollar spent. As with any new construction practice, HPAs come with some previously unsolved challenges. Installers must be able to reach the truss top chords and that becomes difficult for roofs over 8’ tall. Recently these challenges have resulted in cost increases and reduced contractor pools as installers without the right tools/solutions and/or safety concerns decline to bid projects with tall roofs. H&S has reviewed many alternatives and potential solutions.  Below is a summary of the options, trade-offs, and our recommendation:

Partial HPA

Install insulation to highest point possible, leave remaining portion uninsulated

  •    Pro: eliminates insulation in difficult to reach areas
  •    Con: requires an added air barrier sealed at all sides
  •    Conclusion: not worth it, air barrier adds cost and has same installation challenges

False Roof

Install cap trusses above 8′-0″ height to create a false roof that could be sheathed and insulated

  •    Pro: keeps insulation within reach of an installer walking on platform at the truss bottom chords
  •    Con: requires roof sheathing at false roof and high/low vents at attic above false roof
  •    Conclusion: not worth it

Remove HPA

Revise T24 to add different measures (most often ERV/HRV) replacing HPA

  •    Pro: keeps insulation at truss bottom chords only and reduces insulation costs
  •    Con: added cost of measures, ERV/HRV option is temporary as these components will be substantially de-rated at the  end of 2020.
  •    Conclusion: potential short-term solution on a project-by-project basis, but long term will result in higher construction costs

Temporary Platform

Install temporary horizontals on trusses to support a working platform within 8’ of the roof peak

  •    Pro: provides a working surface for installers, relatively inexpensive
  •    Con: scoping challenges as most insulation contractors will not install the member themselves
  •    Conclusion: most cost effective solution, builder can add the material and install for the horizontals into the framing scope so all parties bid it appropriately