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The Custom Residential Architects Network (CRAN®) Knowledge Community develops knowledge and information to benefit architects who are engaged in, or who are interested in learning more about, custom residential practice. CRAN® presents information and facilitates the exchange of knowledge and expertise to promote the professional development of its members via discussion forums, national symposia and conventions, publications, and local activities.

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  • 1.  Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 26 days ago

    In NJ we have adopted the 2021 version of the IBC and IRC at the beginning of 2023, and along with the new code came requirements for higher insulation values. Previously under the 2018 version code could be satisfied by a 2x6 wall with R20, or a 2x4 wall with R13 and R5 continuous insulation. Now under the 2021 version the whole State must provide R20 + R5 continuous, or R13 + R10 continuous, or a single cavity wall of R30. I've found that during the past year that every builder I discussed this with was unaware of the change - and some I caught in mid-bid where they had gravely mis-estimated the work they would need to supply. Furthermore over half the architects I spoke to about this were also unaware of the change. 

    I became very concerned because the overwhelming implication is that the continuous insulation layer must be at the exterior, and I was witnessing an entire State of builders being thrown into detailing flashing and water tightness with an exterior layer of insulation which they had zero experience with. There are alternates to this, and in fact the 2021 code introduced a table of minimum U-Factor values which bypasses the familiar table of insulation values. Another run-around is the Res-Check software package where the option to measure the total performance can prove compliance with alternate assemblies. However builders certainly, and admittedly most architects are not in the routine of calculating U-Values of their wall assemblies, and in fact Res-Check is quite limited in the format of data entry for insulation - its cavity or continuous only.

    Some may argue that the code does not require the continuous layer to be exterior, but that does not hold up. The rush of material manufacturers to bring to market products that are specifically aimed at R5 continuous exterior insulation is palpable. Sheathings with insulation laminated, rigid insulation with air water barrier pre-laminated, dense and rigid batts are all being touted as the solution. These companies have invested millions in developing and promoting products to answer what is obviously a call to exterior insuation in the building code.

    So I along with a couple of colleagues from New England who have already been working under the R20+5continuous requirement for many years have written a White Paper to document compliance of a greatly simplified compliant wall assembly consisting of R20+R6 furred continuous insulation located at the interior. This requires much less work than continuous exterior insulation, and more importantly requires no new skills or techniques for successfully flashing and making the exterior side weather tight. And the performance is marginally better than R5 continuous. 

    It is our intention to share this widely, so that architects and builders are not caught unprepared for the new code requirements when and if they come to your location the way the have just landed on New Jersey. The white paper can be downloaded from this link:

    White Paper 20+6fci wall 14Nov2.pdf

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    White Paper 20+6fci wall 14Nov2.pdf
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    Please share with your colleagues and builders. 



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    Gregory La Vardera
    Gregory La Vardera Architect
    Merchantville NJ
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    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 2.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 23 days ago

    I see a WUFI model was created, but do not see a hygrothermal analysis. Could you please point us to that data or share, if not included in the white paper?  The location of the vapor barrier may prove problematic in some (micro)climate zones. 



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    Jonathan Huffmaster AIA
    Architectural Design Group, pllc
    Ham Lake MN
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    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 3.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 23 days ago

    Hi Jonathan, thanks for looking. 
    In short no hygrothermal analysis is included in the White Paper because the Code tables that relate insulation requirements does not address this.

    That said the assemblies described in the Code, and the alternates we describe are not universal - no assembly is. People building in "micro" climate zones will always have to be mindful of the assemblies vapor performance. I will say that the assembles we describe with continuous insulation at the interior side are much more resilient than Code described walls with vapor retarding exterior insulation. 

    Greg



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    Gregory La Vardera
    Gregory La Vardera Architect
    Merchantville NJ
    ------------------------------

    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 4.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 22 days ago
    Edited by Paul M. Reynolds AIA 22 days ago

    My understanding is that's the entire point of the exterior insulation... not for insulation's sake but to keep the sheathing warm(er) and reduce the risk of condensation. Pushing the dew point...

    I need to dig into the white paper, yet... It's also possible that I'm missing something.



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    Paul Reynolds AIA
    HAUS | Architecture For Modern Lifestyles
    Indianapolis IN
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    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 5.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 22 days ago

    Paul, 

    Exterior insulation can certainly warm the inside surface of the sheathing, and this can prevent condensation – if you are going to let interior conditioned air un-fettered access to your stud cavity. However, if you are controlling vapor at the inside of your wall assembly then in theory it should not be reaching the sheathing in any great volume to cause condensation. The caveat here is that kraft faced insulation is far from continuous, and electrical device boxes make regular holes in it. 

    When you use an exterior insulation that is not vapor open - such as a foam insulation layer - then you are adding a vapor retarder to the exterior (on top of your sheathing which is already a vapor retarder). So when you are going to do this, best practice is not to also put a vapor retarder at the interior - because it should be easy for the wall to dry-out in at least one direction. 

    When you use an exterior insulation that is vapor open - like mineral wool - this concern goes away, and you can control vapor at the interior side, which is more ideal and more resilient for heating climates in the Zones in question here.

    Why is that? Because controlling vapor's entry into the stud cavity is always more effective placed at the interior side. If the wall experiences "out of range" conditions it will still perform perfectly. By "out of range" conditions I mean like when an Arctic air mass sinks into the central US, and temperatures drop to the teens in Texas. While this is going on, Northern central States are experience -30F. Not just overnight either - we seen it recent winters for a week or more. Under these conditions the vapor closed exterior insulation wall may experience back of sheathing temperatures below the interior dew point for extended periods. Will it make your house fall down? No. Will it cause mold? Maybe. But in general, its clear that this is not a smart approach in many locations.

    This whole discussion about the merits of where you control vapor in a wall assembly is way beyond the purpose of this White Paper, which is just to document that the interior continuous insulation wall is compliant with Code. The benefit is that these walls are easier and faster to build, and cost less in time and money.



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    Gregory La Vardera
    Gregory La Vardera Architect
    Merchantville NJ
    ------------------------------

    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 6.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 21 days ago

    And in very northern climates, things don't dry out. So best to keep the moisture on the warm side of an interior vapor retarder as much as possible.



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    Mike Mense FAIA
    Architect, Writer, Planner, Painter
    mmenseArchitect
    mensenyc on Instagram
    Hamilton Heights, NYC and Snohomish WA
    ------------------------------

    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 7.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 22 days ago
    Thanks for sharing this Greg. What a great resource!
     
    I worked on a recent addition, specifying 1 7/16" THICK ZIP SYSTEM R-6 INSULATED WALL SHEATHING AND FLASHING TAPE SYSTEM, and utilizing ResCheck for energy compliance submission.
     
    Have not dove into the details of the White Paper to see if any of the solutions utilize insulated Zip Systems, but thought I's offer it as an option.
     
    Really appreciate the resource for future projects!
     
    Thank you,
    Brooke

    D. Brooke Robinson

    16 Idlebrook Lane
    Aberdeen, NJ 07747
    p: 732.441.3532
    e: brooke@draworkshop.com

    w: www.draworkshop.com




    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 8.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 22 days ago

    Please dig into the White Paper. The alternate is a furred continuous insulation layer at the interior side, which does not rely on the expense of Zip's insulated sheathing, or the complexity of exterior side detailing that comes with other forms of exterior insulation. It offers slightly better performance than the continuous exterior R5, and much easier to build. This emerged out the situation in my state of NJ where builders, and architects, have really been caught with their pant's down - inexperienced at detailing and building exterior insulation, with the grace period for the 2018 code recently expired.

    In my own practice I have a embargo on Zip sheathing. I need 50yrs before I believe that tape is a suitable replacement for lapped flashing details. Note - I will be dead by then, so this is one choice I can simply take off the table.



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    Gregory La Vardera
    Gregory La Vardera Architect
    Merchantville NJ
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    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 9.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 21 days ago

    Since we are all visual orientated, and I hate to type, I thought I would share a few videos that have some good information regarding continuous insulation.  My gig is multi-family, and we have been dealing with ci for some time, especially in the colder climates.  When you have several thousand windows in one project, you learn quickly how to detail ci correctly and cost effectively. It is the future, so embrace it and deliver a better building to your client.

    https://buildingscience.com/video/perfect-wall-finally

    https://www.youtube.com/watch?v=5-Fy5a9WPV4

    https://www.youtube.com/watch?v=sV7yC4XGeTE

    https://www.youtube.com/watch?v=W5zR3GeUjG4

    https://www.youtube.com/watch?v=ZkgJ7BzrQp8

     

     

    HLR Logo

     

    Tom Taylor, AIA

    Hensley Lamkin Rachel, Inc.

    14881 Quorum Dr, Ste 500, Dallas, TX  75254

    O: 972.726.9400 x131 | C: 469.766.8784 | W: www.hlrinc.net

     

    Member International Institute of Building Enclosure Consultants

    2027 International Residential Code Building Code Committee

    2024 IECC Residential Envelope and Embodied Energy Committee

     

     




    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.


  • 10.  RE: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

    Posted 20 days ago

    Respectfully Tom - glad you have had good experiences with exterior CI, but the situation we in NJ, and other states in Zones 4&5 that move from 2018 to 2021 codes find themselves in is an entire local industry, builders And architects, with little to no experience in exterior CI, which is clearly a recipe for state wide building errors that will emerge sometime in the future. 

    The fact is the interior side work is easier, faster, and less costly in time and money. Thats a great advantage you could deliver to your clients.

    I have no prejudice against exterior side CI, and in fact I believe it can be an effective part of a multi layer wall. I would favor a wall with R5 exterior and R6 interior over a wall with R10 on either side. Two thermal breaks outperform a single thermal break for the same amount of insulation. But I don't encounter code requirements for that level of performance in my region. Unless you are pursuing a performance standard certification greater than code it would not make sense. 

    As far as the video links. I've watched them all in the past, and frankly I find the "Perfect" Wall imperfect. If it was perfect it would be more affordable than other options and we would see it being used widely. While its author is qualified, I don't find the cult of personality around him helpful, and actually quite embarrassing for our profession at times. If he inspires you to better work, then good for you.

    best, Greg



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    Gregory La Vardera
    Gregory La Vardera Architect
    Merchantville NJ
    ------------------------------

    Jain us at AIA24 for practice-related sessions! June 5 to 8, Washington, DC, click here to learn more.