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Continuous Insulation – Part 3

April 15, 2011

For Part 1 of the series, click here.

For Part 2 of the series, click here.

Sorry for the delay in posting. I had to work out some legal and liability issues on some of the information in this post before publishing . . .

When I left the last post, I was about to give away the final and best solutions I have found to providing Continuous Insulation (CI) in a metal-framed wall with the widest variety of cladding materials.  I also want to leave you with some outstanding issues I have yet to resolve so you can be aware of them and press cladding and insulation manufactures to get the issues resolved. I’m also going to provide a list of links to manufacturers I have spoken with that have been helpful in one way or another, or are now aware of the issues . . . With that, let’s wrap this up . . .

The first solution I found is a proprietary system. I’m not against proprietary systems, but they often come with a price-tag. I would much rather find a solution that uses materials my contractors are familiar with, and if possible, construction methods with those materials that are simple and make sense to my contractors.

The first solution, a proprietary system, uses a specialized girt, appropriately named a “CI-Girt,” by Knight Wall Systems. The biggest advantage to this system is that the primary girt runs vertically and attaches through to the stud, and if necessary, a horizontal girt is added for cladding attachment. Therefore, the system works for both vertically and horizontally attached cladding systems. These guys are definitely on the right track, but I was not looking forward to specifying a proprietary system from Washington state in by Baltimore buildings . . .

Finally, I found what I was looking for all along . . . someone who has done testing with “normal” stuff and made it work. In fact, they used standard metal hat channels, wood furring, screws, and similar products.  They went so far as to format their data for inclusion in future Model Building Codes.  Since the research is not yet in the codes, you will need to have a structural engineer verify it and specify according to the specifics of your project, but here it is . . .

I highly suggest reading most of the data, process, etc . . . but for a quick run, skip to PDF page 70 (document page 62) for a simple chart.

So there you go . . . there’s the solution . . . but there is still one major problem . . .

Fire codes . . .

In IBC 2009 and other model building codes, there’s information about materials and how they should be used, tested, etc.  For Continuous Insulation boards, particularly Foam Plastics, one of these tests is NFPA 285 (IBC 2009 2603.5).  From what I understand, this test provides standards on how a product should perform within an exterior wall assembly when a fire on the inside of the building laps up the side of a building through an opening such as a window.

In a masonry cavity wall, the thermal mass of the masonry veneer generally allows most Rigid Foam products to work without any  problem. Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), and Polyisocyanurate are all viable solutions, along with Mineral Fiber, some spray-foam products, and more.

However, with thin cladding, such as metal panels, lap siding, etc . . . plastic foam products do not seem to fare well. One manufacturer I talked to actually pointed me to their biggest competitor as one of the only products that will pass this test.

Mineral Fiber Boards seem to work and are commonly used in CI rain screen type wall systems.  The specifier needs to understand the particular water-related issues with mineral fiber, but it is an option if installed correctly.

Dow’s Thermax (ci) is a specially formulated polyisocyanurate that has been tested with a variety of thin cladding material, and seems to be performing well on the NFPA 285 test. In fact, if you’re willing to spend a small amount of money getting your building envelope right, the entire Thermax Wall System shows some great promise that I may address in another post.

I haven’t found definitive answers to whether or not any other Continuous Insulation Product will work with thin cladding materials. I haven’t quite figured out what this article is saying, but other than that, I invite anyone to leave their findings of acceptable products in the comments below.

So, that concludes my series on Continuous Insulation with thin cladding materials. Where would you like to go next?

Andrew Kulp, AIA is Senior Project Architect at Curry Architects in Towson/Baltimore, Maryland. Please feel free to contact us for all of your design needs.

7 Comments leave one →
  1. April 15, 2011 11:54 am

    I missed adding links to manufacturers as promised:

    1. Dow,
    2. OwensCorning:
    3. Nichiha:
    4. Hardie:
    5. Unaclad/Firestone:
    6. Centria:
    7. Kingspan:

  2. April 15, 2011 10:53 pm

    Thanks, Andrew. The three parts, taken together, provide a great deal of detail and analysis. As I have mentioned before, my current position doesn’t deal with this level of design detailing – but I hope to need this info some day.

    I wish we had a central place for such research. I began a website for Architects to address questions and concerns from the general public ( “Engaging Architects” ) but I don’t know of a central clearinghouse for this type of content.

    As a fellow architectural blogger, I’d like to know more about the legal issues you had to address in order to present these blogs.

    Again, thanks for sharing this CI code and detailing information.

  3. November 16, 2011 5:27 pm

    UPDATE, 11-16-2011:

    The Insulated Metal Panel industry has developed some great products to answer the problems of Continuous Insulation and thin cladding . . .

    The following manufacturers have all developed an insulated metal liner panel that has some sort of attachment system similar to a hat channel that can either be horizontal or vertical. Panels can be in a variety of thicknesses from 2″ (approx R-14ci) and up that far exceed any current code requirements.

    Kingspan (actual product not listed on web site at this time):
    *Note: Kinspan offers a Brick Ledge Clip to a brick veneer!

    Centria Metalwrap:

    MetlSpan HPCI:

  4. John deMaere permalink
    June 7, 2012 9:37 pm

    I think that the designers of building have finaly started a process of reflection on what needs to happen for buildings to eventually become highly efficient from an envelope performance point of view. I think we are at the very infant stage of a much larger change that will in the end not just lead to buildings having ” net zero” energy demands, but eventually producing more than what they use, as that will prove to be needed ito power automated factories. The changes will be sizeable and the potential rewards for those who get it right will be sizeably rewarded.
    EIFS is a system that has had challenges in the past when used over lighweight envelopes but works very well on mass walls, They have passed all multi storey fire tests (15 minute stay in place), and there are not many ways to have a truly continuous insulation layer.
    If you have highrises going up around you, question how the concrete if it only gets paint on the outside can really have CI at all slab edges. The thermal losses in a slab edge of 7.5 inch is equal to the thermal loss in a 7 foot high insulated wall, Kind of counterproductive to insulate at all wouldn’t you say. CI girt of Knight is good but fasteners are still conducting thermal energy through insulation (still allowed for now). A little expensive too for a framework. Most plastic foam (not part of a system) will need to be covered by 25mm of masonary or more. My findings are that gravitational load of 25mm stucco or so is way less than the possible wind loading forces (particularly at the corners and flat roof edges) and manufacturers of systems will have to follow some research that has been done by the foam sheathing coalition (of which Dow’s Thermax belongs for instance).

  5. Louis Medcalf, FCSI, CCS permalink
    October 3, 2012 11:24 am

    The issue with NFPA 285 testing is that is for the entire wall assembly [like UL or GA designs for interior fire barriers], but most tests at present are for specific proprietary foam plastic insulations and there is no code provision for substituting equivalent products from other manufacturers. Note also that IBC 2603.5.5 applies to masonry cavity walls also. This provision is controversial because many industry experts question whether there is actually enough loss history data to support this costly and restrictive provision. The provision has been in the IBC since the 2000 edition but has not been enforced in many jursidictions. That means the ICC will be reluctant to rescind or modify 2603.5.5 and, in fact, it was reaffirmed this past spring.

    A note on EIFS [aka the “kudzu of construction”]: code compliance is based on Evaluation Reports and testing. Some manufacturers require use of Type X sheathing and some [last time I looked, which was a few years ago] even require Type X gypsum board on the interior of the wall.

    Thanks very much for an informative and helpful series of articles! Please consider posting to and other CSI hangouts.

  6. April 25, 2013 4:48 pm

    UPDATE: 02-25-13

    More manufacturers are beginning to meet NFPA 285 test on their products, so there are now options beyond Dow Thermax(ci)

    RMAX ECOMAXci is by all accounts an equal to Dow’s product:

  7. January 10, 2014 3:20 pm

    Update; 01-10-14

    More insulation manufacturers to consider:

    Hunter XCi has developed an entire line of products to look at:
    Johns Manville is starting to develop products that may meet some assemblied:

    Any others out there?

    Also, look into IBC 2012, Section 2603.5.7 if you really want to know where all this is coming from:

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