Custom Residential Architects Network

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. 

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
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Original Message:
Sent: 03-25-2024 05:42 PM
From: Jonathan Huffmaster AIA
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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. 

------------------------------
Jonathan Huffmaster AIA
Architectural Design Group, pllc
Ham Lake MN

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
------------------------------


Original Message:
Sent: 03-25-2024 11:01 PM
From: Gregory La Vardera
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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

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


Original Message:
Sent: 03-25-2024 05:42 PM
From: Jonathan Huffmaster AIA
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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. 

------------------------------
Jonathan Huffmaster AIA
Architectural Design Group, pllc
Ham Lake MN

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.

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.

------------------------------
Paul Reynolds AIA
HAUS | Architecture For Modern Lifestyles
Indianapolis IN


Original Message:
Sent: 03-25-2024 11:01 PM
From: Gregory La Vardera
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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

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


Original Message:
Sent: 03-25-2024 05:42 PM
From: Jonathan Huffmaster AIA
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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. 

------------------------------
Jonathan Huffmaster AIA
Architectural Design Group, pllc
Ham Lake MN

I just wanted to update this thread with additional information that I came across quite accidentally. I was presented with an ad for a website:

continuousinsulation.org

This site has extensive and deep information on how to properly implement continuous exterior insulation in construction, although it appears primarily focused on foam insulation products. The information is good, and accurate - a good guide if you intend to specify the products featured in its information. There is even an freestanding PDF document which is a Continuous Insulation RESOURCE GUIDE. All of this information is gathered, and formatted, and presented free of charge.

A closer look reveals this site is authored by Applied Building Technology Group - a large building science consultancy. I have no proof, but I suspect this whole endeavor is a paid effort on the part of Applied Building Technology Group, presented and posing as a dot-org, when in all likelihood this is a coordinated ad campaign posing as public advocacy. Large Building Science consultants often offer reports on findings funded by their clients as free public advice, coincidently recommending their clients products, because after all that is what was the subject of the paid study. This is quite common. It is up to us to be aware of these practices, and separate the advertising from the advice. 

None of this is meant to condemn or accuse ABTG of any wrong doing, but rather to demonstrate the immensity of the industry pressure on the adoption of continuous exterior insulation, and the strong held belief of industry that this is in fact what the code is calling for. Remember - it is not, and the interior side continuous insulation method detailed in the White Paper is faster, easier, and less expensive in money and time. Think twice before you burn your client's budget on exterior side continuous insulation.

I just wanted to update this thread with additional information that I came across quite accidentally. I was presented with an ad for a website:

continuousinsulation.org

This site has extensive and deep information on how to properly implement continuous exterior insulation in construction, although it appears primarily focused on foam insulation products. The information is good, and accurate - a good guide if you intend to specify the products featured in its information. There is even an freestanding PDF document which is a Continuous Insulation RESOURCE GUIDE. All of this information is gathered, and formatted, and presented free of charge.

A closer look reveals this site is authored by Applied Building Technology Group - a large building science consultancy. I have no proof, but I suspect this whole endeavor is a paid effort on the part of Applied Building Technology Group, presented and posing as a dot-org, when in all likelihood this is a coordinated ad campaign posing as public advocacy. Large Building Science consultants often offer reports on findings funded by their clients as free public advice, coincidently recommending their clients products, because after all that is what was the subject of the paid study. This is quite common. It is up to us to be aware of these practices, and separate the advertising from the advice. 

None of this is meant to condemn or accuse ABTG of any wrong doing, but rather to demonstrate the immensity of the industry pressure on the adoption of continuous exterior insulation, and the strong held belief of industry that this is in fact what the code is calling for. Remember - it is not, and the interior side continuous insulation method detailed in the White Paper is faster, easier, and less expensive in money and time. Think twice before you burn your client's budget on exterior side continuous insulation.