Building Performance Knowledge Community

1.  James Hardie Reveal Panel

Posted 11-06-2012 10:49
And for months I have been thinking I was the only architect fascinated by the confluence of continuous insulation, thermal breaks, NFPA 285, and non-brick cladding on building 2 -stories or more...

As it appears we are diverting from the specifics of James Hardie Reveal Panel  into a larger discussion about new ways of designing and detailing cladding based on energy conservation and limited by concerns about fire propogation, and seemingly not completely integrated in the industry an exciting time and an example of the benefits of this discussion group.

Our state and local AHJ's enforce NFPA 285.  We have a project under construction using a combination of relatively new features:  Continuous liquid applied air barrier over gyp sheathing, 2" continuous insulation (Hunter basis of design), thermally improved (possibly thermal broken) panel support system (Knight basis of design). 

We have another project under construction using the Dow system with no sheathing.  I anticipate learning a lot throughout the submittal and construction phase and incorporate lessons learned into future projects.

Yet a 3rd project about to bid uses Trespa panels, we had to use mineral wool continuous insulation to meet NFPA 285, which concerns me with our hot, humid climate.

I am interested in keeping this dialog open with this group, let's learn from each other's research and experience.

Gregory Soyka AIA
Charleston SC

2.  RE:James Hardie Reveal Panel

Posted 11-07-2012 10:29
NFPA 285 testing is an assembly test but the specific need for NFPA 285 testing is a function of the materials selected, which edition of the code is in use, and the acceptability of engineering judgement letters by both the design professional and the AHJ.  Complicating the matter is there is no centralized list of accepted/tested assemblies, such as UL, to serve as a point of reference and most projects cannot afford the time or cost of specific NFPA 285 testing.

For example, the code requirement to test weather resistive barriers and high pressure laminates first appeared in IBC 2012, while the requirements for foam plastic date back to 2000 (and even earlier under the UBC).

Wall detailing has become increasingly complicated not just by the codes but by the multitude of product choices we must make. Weather resistive barriers (WRB) can be non-adhered sheets, adhered sheet membranes, or fluid applied membranes. The performance of these products are not equivalent and are not appropriate for all projects. Add to the mix that contractors and installers (and designers) can lack basic knowledge in installation of the specific products used. 

I suggest:
- Confirm the basis of individual manufacturer claims of NFPA 285 compliance. (tested assembly, engineering judgement, or alternate compliance path)
- Verify your local code and jurisdictional requirements.
- Design for redundancy (use sheathing with a WRB) and durability (durable design is sustainable design). Consider mechanisms for failure; what happens when that WRB is punctured by a fastener? What is the reduction in R-value for wet insulation? Are adjacent materials compatible in short and long term?
- Select products with a proven record of performance (see durability). Understand your clients, and your own, tolerance for risk.
- Verify compliance of the installed product.

David Bliss AIA
Simpson Gumpertz & Heger
Waltham MA

3.  RE:James Hardie Reveal Panel

Posted 11-12-2012 16:39

Gregory, totally agree in keeping this conversation going regarding all these issues.

I'm satisfied that we'd be successful using a girt/sub-girt system to hang the Hardie panels over a weather-resistant barrier.  Then use a mineral wool outboard of the barrier, keeping 3/4" of air space.

Andrew Craven AIA
Lyall Design Architects
Virginia Beach VA