Custom Residential Architects Network

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

Please share with your colleagues and builders. 

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. 

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

Please share with your colleagues and builders. 

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

Original Message:
Sent: 03-22-2024 04:53 PM
From: Gregory La Vardera
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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

Please share with your colleagues and builders. 

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

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

Original Message:
Sent: 03-22-2024 04:53 PM
From: Gregory La Vardera
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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

Please share with your colleagues and builders. 

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

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

Original Message:
Sent: 03-22-2024 04:53 PM
From: Gregory La Vardera
Subject: Code Wall Assemblies - Alternate to Code described R20+R5continuous insulation.

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

Please share with your colleagues and builders. 

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

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

Please share with your colleagues and builders. 

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

Please share with your colleagues and builders. 

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

Please share with your colleagues and builders. 

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

Please share with your colleagues and builders.